Hackspace Manchester https://hacman.org.uk A place for people who make things to make things Mon, 30 May 2016 18:44:55 +0000 en-GB hourly 1 Space 3.0 Buildout Day 1 https://hacman.org.uk/space-3-0-buildout-day-1/ Wed, 13 Apr 2016 20:24:20 +0000 https://hacman.org.uk/?p=6338 So, day one of the buildout. We concentrated on sealing up broken windows (hopefully short term until our double-glazing units are fitted!), putting the wood workshop back together, getting snackspace set up for sugar and brews, and assembling the shelf units along the backwall.

Thanks to Ben, Greg, Bob, Fahad, Edd, Ruth and Richard for their help today.

The Workshop

photo111281031137569608 photo111281031137569607

We’ve chucked together the ‘messy’ workshop (the one with all the power tools!) partially, to give us an area to mend and make bits of the space as we’re building out the rest of the room.

Snackspace

photo111281031137569605

Snackspace is set up as a brew station, with the project-a-sketch laptop-bench acting as a phone charging / pocket-rubbish storage area.

The ‘Great Wall’

photo111281031137569606

This chunk of wall is currently acting as temporary storage for things until we have the part of the space where they actually go assembled and the boxes can be sorted off there.

ToDo

photo137217419515111773

Theres still a lot to do!  Work party Day 2 will be happening on Thursday the 14th from 1pm-ish.

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555 Flyback Driver and Plasma Speaker Part IV http://langster1980.blogspot.com/2016/03/555-flyback-driver-and-plasma-speaker_15.html Tue, 15 Mar 2016 23:08:00 +0000 https://hacman.org.uk/?guid=098ddb3ba85d75d26efd54b2cc5a0af2
It has also become apparent that the high current power supply not being current limited has destroyed the +12 Vdc on the PCB at least 5 times!  This is probably due to poor constructional technique (my bad soldering) and the tracks not being thick enough to carry the amount of current present in normal operation.  I was playing with the circuit last night after having put the high voltage probes into a laser cut case (which worked perfectly) I managed to catastrophically damage components...Standard form for me to be honest....that is why I call this prototyping!

The issues I'm having are all to do with construction and design choices that I made when I initially designed the plasma speaker PCB.  I'm going to design a new version which improves the situation:
  • Increase current rating of all tracks carrying +12V or GND.
  • Incorporate the Class A amplifier into the circuit so that everything is on one PCB
  • Increase the gain on the Class A amplifier as it still (in my opinion) is not loud enough
  • Move the components which get incredibly hot off the PCB and onto the heatsink.
First off I think I really need to find out just how much current the main switching transistor is subjected to.  This is going to involve checking the datasheet for the transistor and performing some ohms law.  I hate maths but in this case it has to be done...I cannot assume all will be well if I don't check the current requirements of the 12 Vdc conductor.

Here is the new schematic with all of the circuitry on one sheet:


The datasheet for the IRFP250 is here:


From the datasheet we can see that the RDSon parameter of the transistor is 0.085 ohms.  If we assume that the dc resistance of the flyback transformer is also quite low then the amount of current constantly present as the transistor switches will be high...The energy from the flyback voltage at the primary must also be taken into account.

In order to discuss this I should really link in a page discussing how flyback transformers function:

EE Times article on flyback transformers

Wikipedia Entry on Flyback Transformers

My schematic diagram has not ever shown the actual flyback transformer which is actually a transformer with 10 turns on the primary core and several thousand turns on the secondary core which is then connected to an internal 'flyback' diode and capacitor.



Basically what this means is that the output of the transformer and associated energy output is related to the winding ratio, the capacitor and the load applied at the output which in this case is an arc through the air.

For the purposes of calculating how much current will be flowing in switching transistor part of the circuit I'm going to simulate the circuit.  The reason for simulating is that it's quicker for me than calculating all of the Ohms law required on paper....Here is the circuit after simulating:


Well....that explains why the MOSFET Q3 got so hot and needed such a large heatsink along with the flyback diode D1 and the 120 Ohm resistor....1.6A constantly flowing in that part of the circuit is a great deal and also explains why the 12 Vdc conductor and the conductors in the FET part of the circuit needs to be as thick as possible.  I have made assumptions on the turns ratio of the transformer but it doesn't really matter as I have seen from the power supply current meter that I'm using to power this circuit that these calculated current values are close enough....Therefore the design needs to account for this 2 Amp current being present - I actually think the instantaneous peak currents will be considerably higher than this and the current is also higher when the audio modulation is applied.

To that end we need to redesign the PCB to take this into account.  Here is the new PCB layout:

Top Layer Of PCB

Bottom Layer of PCB

Both Layers with Dimensions

I then etched and populated the PCB.  I have found that the circuit works better but still had some issues.  I have mounted the 120 ohm 5 Watt resistor on the heat-sink along with the clamp diode which I have swapped for a TO220 packaged version.  I also changed the operating frequency of the 555 oscillation by changing the value of C1 (in the uppermost schematic) to 100 pF.  This changes the oscillation frequency to somewhere always above 20 kHz which removes an annoying high pitch whistle when the circuit is in use.

There are still issues with the circuit but I believe this is now as good as it will probably get.  I need to obtain a suitable high current power supply and mount the circuitry properly to make it easier to move around.  I have had a lot of fun developing this circuit and visually it's really attractive.  It's practicality is exceedingly limited.  A plasma speaker loses a great deal of fidelity with low frequency bass sounds, generates significant amounts of ozone, uses a large amount of electrical power and is fundamentally dangerous because of the high voltage DC that is present.

Here is a video of me playing around with it using an electronic keyboard to provide the audio input.


That's all for now - take care people, especially with high voltage dc circuits and plasma speakers!
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555 Flyback Driver and Plasma Speaker Part III http://langster1980.blogspot.com/2016/03/555-flyback-driver-and-plasma-speaker.html Sun, 06 Mar 2016 13:32:00 +0000 https://hacman.org.uk/?guid=ca916e1b64dec219066aec863c2799a6


It actually creates a significant amount of high voltage and works very well.  I would caution anyone else attempting to replicate this circuit to please be very careful.  I haven't given myself a shock yet but it could happen and will hurt if it does....Exercise sensible precautions please!

Here is the previous post in case people need to catch up:

555 flyback driver and plasma speaker part II

I have found that the 3D printed HV probe holders work quite well.  I also have found that setting the distance between the probes is critical to obtaining a reproducible arc and that the constant re-strike of the arc causing the audio to sound terrible.  From experimentation I have found that the audio signal from my mobile phone is more than enough to drive the 555 modulation pin when it isn't capacitively coupled.  When capacitive coupling is added the audio is barely heard.  The capacitor on the audio input reduces the hissing considerably.  Here is a video showing the current audio output of the plasma speaker...it sounds pretty terrible but it does work:



I have decided to do two things....improve the HV probes and provide a simple class A audio amplifier to the pin 5 input of the 555.  This should improve the sound and get rid of the horrible hissing!

So to that end I have designed a very simple single transistor class A amplifier using a BC548 transistor.  Here is the schematic:

In designing the circuit I referred to this website...which is rather useful for this kind of thing:

http://www.learnabout-electronics.org/Amplifiers/amplifiers40.php

I knew how to design a Class A amplifier well enough but I had forgotten how to select the components values correctly...in particular I wanted to increase the low frequency response and limit the bandwidth of the amplifier to reduce the high frequency response.

The circuit works fairly simply...An audio signal from a suitable source is presented at the 3.5 mm headphone jack input - only one side of the audio signal is provided - this amplifier is mono. This is then passed to C1 - a 1 uF electrolytic capacitor which is used to remove any dc offset and chosen in such a way as to not overly affect the bass response of the amplifier (more on this later).  The next components in the circuit are R3 and R4 which bias the NPN BC548 transistor into constantly being ON.  These values are set by ohms law.  We need at least 0.7 volts to turn an NPN transistor ON. Lets do the maths just for fun:

Ohms Law; V / R = I

In this case:

V: 12 Volts
Rt: R3 + R4 which is 120 kΩ + 10 kΩ = 130 kΩ

I = V / Rt

I = 12 V / 130 kΩ

I = 9.23076923077 * 10^-5 A or 92.3 µA

The voltage applied to the base of the BC548 transistor can be calculated by = I * R4
therefore the voltage applied to the base of the BC548 transistor:

92.3 *10^-6 A * 10 kΩ

The voltage applied to the base of the BC548 transistor is 0.923 Volts or 923 mV

The circuit has been designed so that 0.923 volts is always applied to the base pin of the transistor to 'bias' the transistor ON.  The audio signal applied will increase this voltage and be amplified.  The next components applied to the collector of the transistor are a 10 kΩ potentiometer and a 100 Ω resistor.  At the emitter of the transistor we have another 10 kΩ  potentiometer and a 10 uF capacitor. All of these components combined set the gain of the amplifier. There are formulae that can be applied to calculate the amount of gain.  I guessed at it...It's not particularly important in this case. When the potentiometers are at maximum (according to my simulations) the input signal is amplified roughly 130 times greater than the input...the amount of gain is controlled both 10 kΩ  potentiometers which can be set by the operator.  The 10 uF electrolytic capacitor C3 is known as the emitter decoupling capacitor and is added to prevent any stray audio signal being present on the emitter pin of the transistor.

Finally at the output of the amplifier we have a 1 nF ceramic capacitor C4 and a 10 uF electrolyitic capacitor C2.  The electrolytic capacitor C2 prevents any dc voltage being passed to the next stage of the circuit, in our case, pin 5 of the 555 timer. C4 is used to limit the bandwidth of the amplifier.  In this case I have set all of the capacitor values to set the amplifier's frequency bandwidth to be between 200 Hz and 20 kHz which is roughly the range of human hearing.

I simulated the circuit in order to check what the output would be like and check the gain would be sufficient and to verify the frequency response.  It was helpfully not clipped and gave a good amplified approximation of what was to be expected.

Here are the results of the simulation...I have placed probes at the more interesting points in the circuit:

Simulation Schematic
Here is the simulated oscilloscope output:


The input signal is shown with the blue trace, the red trace shows the amplified output.  The output is inverted but that won't matter in this case.

The really good thing about simulating circuits is that the frequency bandwidth can be checked without actually building the circuit.  Here is the simulated audio frequency response of the amplifier:

If the capacitor values C1, C3 and C4 are changed for different values the frequency response of the amplifier is significantly affected.  C1's value changes the bass frequency responses, C3 changes the treble response and C4 changes the bandwidth of the amplifier.  In this case I have tweaked the values to try to give the best response between 200 Hz and 20 kHz without losing too much bandwidth.

Because its me I've designed a simple single sided PCB for this circuit.  It could easily be made on veroboard (stripboard) or using some other method.

Top Layer of PCB
Bottom Layer of PCB


Here is a render of the PCB to show how it will look once etched and populated:

Top View of Class A Amplifier Render
ISO view of Class A Amplifier Render
Here is the bill of materials:

Part Value Device Description Vendor Part Number Quantity Cost







(£)
12VDC_INPUT N/A M025MM Standard 2-pin 5mm screw terminal Farnell 9632972 1 0.245
AUDIO_OUT N/A M025MM Standard 2-pin 5mm screw terminal Farnell 9632972 1 0.245
C1 1uF CAP_POLPTH1 Electrolytic Capacitor Farnell 1236686 1 0.0464
C2 10uF CAP_POLPTH1 Electrolytic Capacitor Farnell 9451056 1 0.034
C3 10uF CAP_POLPTH1 Electrolytic Capacitor Farnell 9451056 1 0.034
C4 1nF CAPPTH1 Ceramic Capacitor Farnell 1141779 1 0.0758
C5 100uF CAP_POLPTH1 Electrolytic Capacitor Farnell 1902882 1 0.0345
C6 100nF CAPPTH1 Ceramic Capacitor Farnell 1141775 1 0.0721
JP1 N/A AUDIO-JACKPTH 3.5mm Audio Jack Farnell 1608405 1 0.534
R2 100 RESISTORPTH-1/4W ? Watt Carbon Film Resistor Farnell 9342397 1 0.0523
R3 120k RESISTORPTH-1/4W ? Watt Carbon Film Resistor Farnell 9342540 1 0.0492
R4 10k RESISTORPTH-1/4W ? Watt Carbon Film Resistor Farnell 9342419 1 0.0523
RV1 10k POTALPS-KIT PCB Mount Variable Resistor Farnell 1191725 1 1.4
RV2 10k POTALPS-KIT PCB Mount Variable Resistor Farnell 1191725 1 1.4
T1 BC549 BC549-NPN-TO92-CBE BC549 NPN Transistror Farnell 2453797 1 0.238














Total 4.5126

Again I haven't factored in the cost of the PCB or it's manufacture but it would be reasonable to estimate the total cost of the project to be around £6.00

Here is a quick video showing the circuit in operation with the plasma speaker.  The audio is very much improved!


Now I need to get back to putting the HV section and the electronics into some sort of casing.  That's all for now - take care people!


]]>



It actually creates a significant amount of high voltage and works very well.  I would caution anyone else attempting to replicate this circuit to please be very careful.  I haven't given myself a shock yet but it could happen and will hurt if it does....Exercise sensible precautions please!

Here is the previous post in case people need to catch up:

555 flyback driver and plasma speaker part II

I have found that the 3D printed HV probe holders work quite well.  I also have found that setting the distance between the probes is critical to obtaining a reproducible arc and that the constant re-strike of the arc causing the audio to sound terrible.  From experimentation I have found that the audio signal from my mobile phone is more than enough to drive the 555 modulation pin when it isn't capacitively coupled.  When capacitive coupling is added the audio is barely heard.  The capacitor on the audio input reduces the hissing considerably.  Here is a video showing the current audio output of the plasma speaker...it sounds pretty terrible but it does work:



I have decided to do two things....improve the HV probes and provide a simple class A audio amplifier to the pin 5 input of the 555.  This should improve the sound and get rid of the horrible hissing!

So to that end I have designed a very simple single transistor class A amplifier using a BC548 transistor.  Here is the schematic:

In designing the circuit I referred to this website...which is rather useful for this kind of thing:

http://www.learnabout-electronics.org/Amplifiers/amplifiers40.php

I knew how to design a Class A amplifier well enough but I had forgotten how to select the components values correctly...in particular I wanted to increase the low frequency response and limit the bandwidth of the amplifier to reduce the high frequency response.

The circuit works fairly simply...An audio signal from a suitable source is presented at the 3.5 mm headphone jack input - only one side of the audio signal is provided - this amplifier is mono. This is then passed to C1 - a 1 uF electrolytic capacitor which is used to remove any dc offset and chosen in such a way as to not overly affect the bass response of the amplifier (more on this later).  The next components in the circuit are R3 and R4 which bias the NPN BC548 transistor into constantly being ON.  These values are set by ohms law.  We need at least 0.7 volts to turn an NPN transistor ON. Lets do the maths just for fun:

Ohms Law; V / R = I

In this case:

V: 12 Volts
Rt: R3 + R4 which is 120 kΩ + 10 kΩ = 130 kΩ

I = V / Rt

I = 12 V / 130 kΩ

I = 9.23076923077 * 10^-5 A or 92.3 µA

The voltage applied to the base of the BC548 transistor can be calculated by = I * R4
therefore the voltage applied to the base of the BC548 transistor:

92.3 *10^-6 A * 10 kΩ

The voltage applied to the base of the BC548 transistor is 0.923 Volts or 923 mV

The circuit has been designed so that 0.923 volts is always applied to the base pin of the transistor to 'bias' the transistor ON.  The audio signal applied will increase this voltage and be amplified.  The next components applied to the collector of the transistor are a 10 kΩ potentiometer and a 100 Ω resistor.  At the emitter of the transistor we have another 10 kΩ  potentiometer and a 10 uF capacitor. All of these components combined set the gain of the amplifier. There are formulae that can be applied to calculate the amount of gain.  I guessed at it...It's not particularly important in this case. When the potentiometers are at maximum (according to my simulations) the input signal is amplified roughly 130 times greater than the input...the amount of gain is controlled both 10 kΩ  potentiometers which can be set by the operator.  The 10 uF electrolytic capacitor C3 is known as the emitter decoupling capacitor and is added to prevent any stray audio signal being present on the emitter pin of the transistor.

Finally at the output of the amplifier we have a 1 nF ceramic capacitor C4 and a 10 uF electrolyitic capacitor C2.  The electrolytic capacitor C2 prevents any dc voltage being passed to the next stage of the circuit, in our case, pin 5 of the 555 timer. C4 is used to limit the bandwidth of the amplifier.  In this case I have set all of the capacitor values to set the amplifier's frequency bandwidth to be between 200 Hz and 20 kHz which is roughly the range of human hearing.

I simulated the circuit in order to check what the output would be like and check the gain would be sufficient and to verify the frequency response.  It was helpfully not clipped and gave a good amplified approximation of what was to be expected.

Here are the results of the simulation...I have placed probes at the more interesting points in the circuit:

Simulation Schematic
Here is the simulated oscilloscope output:


The input signal is shown with the blue trace, the red trace shows the amplified output.  The output is inverted but that won't matter in this case.

The really good thing about simulating circuits is that the frequency bandwidth can be checked without actually building the circuit.  Here is the simulated audio frequency response of the amplifier:

If the capacitor values C1, C3 and C4 are changed for different values the frequency response of the amplifier is significantly affected.  C1's value changes the bass frequency responses, C3 changes the treble response and C4 changes the bandwidth of the amplifier.  In this case I have tweaked the values to try to give the best response between 200 Hz and 20 kHz without losing too much bandwidth.

Because its me I've designed a simple single sided PCB for this circuit.  It could easily be made on veroboard (stripboard) or using some other method.

Top Layer of PCB
Bottom Layer of PCB


Here is a render of the PCB to show how it will look once etched and populated:

Top View of Class A Amplifier Render
ISO view of Class A Amplifier Render
Here is the bill of materials:

Part Value Device Description Vendor Part Number Quantity Cost







(£)
12VDC_INPUT N/A M025MM Standard 2-pin 5mm screw terminal Farnell 9632972 1 0.245
AUDIO_OUT N/A M025MM Standard 2-pin 5mm screw terminal Farnell 9632972 1 0.245
C1 1uF CAP_POLPTH1 Electrolytic Capacitor Farnell 1236686 1 0.0464
C2 10uF CAP_POLPTH1 Electrolytic Capacitor Farnell 9451056 1 0.034
C3 10uF CAP_POLPTH1 Electrolytic Capacitor Farnell 9451056 1 0.034
C4 1nF CAPPTH1 Ceramic Capacitor Farnell 1141779 1 0.0758
C5 100uF CAP_POLPTH1 Electrolytic Capacitor Farnell 1902882 1 0.0345
C6 100nF CAPPTH1 Ceramic Capacitor Farnell 1141775 1 0.0721
JP1 N/A AUDIO-JACKPTH 3.5mm Audio Jack Farnell 1608405 1 0.534
R2 100 RESISTORPTH-1/4W ? Watt Carbon Film Resistor Farnell 9342397 1 0.0523
R3 120k RESISTORPTH-1/4W ? Watt Carbon Film Resistor Farnell 9342540 1 0.0492
R4 10k RESISTORPTH-1/4W ? Watt Carbon Film Resistor Farnell 9342419 1 0.0523
RV1 10k POTALPS-KIT PCB Mount Variable Resistor Farnell 1191725 1 1.4
RV2 10k POTALPS-KIT PCB Mount Variable Resistor Farnell 1191725 1 1.4
T1 BC549 BC549-NPN-TO92-CBE BC549 NPN Transistror Farnell 2453797 1 0.238














Total 4.5126

Again I haven't factored in the cost of the PCB or it's manufacture but it would be reasonable to estimate the total cost of the project to be around £6.00

Here is a quick video showing the circuit in operation with the plasma speaker.  The audio is very much improved!


Now I need to get back to putting the HV section and the electronics into some sort of casing.  That's all for now - take care people!


]]>
The Particle Electron – First Impressions https://skippy.org.uk/the-particle-electron-first-impressions/ Sat, 20 Feb 2016 21:29:36 +0000 https://skippy.org.uk/?p=10885 A while ago I backed the kickstarter campaign for Particle (formerly Spark)’s Electron board, a IOT (internet of things) with a built in 3G modem (2G are available) with global data coverage, recently they shipped,

The Electron Packaging The Electron Packaging The Electron open box The Electron open box The Electron what is the box The Electron on supplied breadboard The Electron powered on Small bag of supplied bits:
2 x  21 ohms resistors
1 x LDR
1 x LED

Setup was as easy as getting it out the box, wiring it up and following the instructions on setup.particle.io (mine is set up using my awsome Mondo card) it offered me the name “nimble-aardvark”.

Once the board is powered up and connected, you get navigated to build.particle.io where you are prompted to start a new project (there is an IDE available on the at Dev Site, but no way as far as I can see of using the Arduino IDE), It is also worth checking out spark.github.io for additional things.

I have downloaded the Local Dev App (still requires web access to do compilation of code), it appears to be a customised version of the Atom text editor.

Particle Dev

Particle Dev

Using the Small bag of parts provided, and the sheet on the solderless breadboard (read the pin assignment as the holes don’t match up) I have wired it up as specified.

Wired up and Powered on

Wired up and Powered on

I loaded up the web IDE (and pulled up the docs) and flashed the example “Blink an LED” to the Particle Electron, the example as provided lists the second LED as on Pin0 when its acctuly on Pin6, so replace line 28:

int led1 = D0; // Instead of writing D0 over and over again, we'll write led1

with

int led1 = D6; // Instead of writing D6 over and over again, we'll write led1

Then click on the button to Flash the code to the device

Options to flash over USB or via 3G

Options to flash over USB or via 3G

Which is all very good, but I can do this with an Arduino… so moving quickly on to using the backhaul for something exciting (I mean I may want to flash an LED in a different country where there is no access to WiFi).

So for turning an LED on and Off over the internet we use this example code:

// -----------------------------------
// Controlling LEDs over the Internet
// -----------------------------------

/* First, let's create our "shorthand" for the pins
Same as in the Blink an LED example:
led1 is D6, led2 is D7 */

int led1 = D6;
int led2 = D7;

// Last time, we only needed to declare pins in the setup function.
// This time, we are also going to register our Particle function

void setup()
{

   // Here's the pin configuration, same as last time
   pinMode(led1, OUTPUT);
   pinMode(led2, OUTPUT);

   // We are also going to declare a Particle.function so that we can turn the LED on and off from the cloud.
   Particle.function("led",ledToggle);
   // This is saying that when we ask the cloud for the function "led", it will employ the function ledToggle() from this app.

   // For good measure, let's also make sure both LEDs are off when we start:
   digitalWrite(led1, LOW);
   digitalWrite(led2, LOW);

}


/* Last time, we wanted to continuously blink the LED on and off
Since we're waiting for input through the cloud this time,
we don't actually need to put anything in the loop */

void loop()
{
   // Nothing to do here
}

// We're going to have a super cool function now that gets called when a matching API request is sent
// This is the ledToggle function we registered to the "led" Particle.function earlier.

int ledToggle(String command) {
    /* Particle.functions always take a string as an argument and return an integer.
    Since we can pass a string, it means that we can give the program commands on how the function should be used.
    In this case, telling the function "on" will turn the LED on and telling it "off" will turn the LED off.
    Then, the function returns a value to us to let us know what happened.
    In this case, it will return 1 for the LEDs turning on, 0 for the LEDs turning off,
    and -1 if we received a totally bogus command that didn't do anything to the LEDs.
    */

    if (command=="on") {
        digitalWrite(led1,HIGH);
        digitalWrite(led2,HIGH);
        return 1;
    }
    else if (command=="off") {
        digitalWrite(led1,LOW);
        digitalWrite(led2,LOW);
        return 0;
    }
    else {
        return -1;
    }
}

I have put the following HTML code at Skippy.org.uk/led.html:

<html>
<head>
<title>Skippy's LED</title>
</head>
<body>
<center>
<br>
<br>
<br>
<form action="https://api.particle.io/v1/devices/nimble-aardvark/led?access_token=ff369c5be4b1b1932bf46e00b5a27128a4a4a554" method="POST">
Tell my LED what to do!<br>
<br>
<input type="radio" name="args" value="on">Turn the LED on.
<br>
<input type="radio" name="args" value="off">Turn the LED off.
<br>
<br>
<input type="submit" value="Do it!">
</form>
</center>
</body>
</html>

I will have a further play, as I have five of these in total.

]]>
555 Flyback Driver and Plasma Speaker Part II http://langster1980.blogspot.com/2016/02/555-flyback-driver-and-plasma-speaker_9.html Tue, 09 Feb 2016 22:56:00 +0000 https://hacman.org.uk/?guid=7b9cc97d7bd8ed8f73b90bc84d7bf12c
Here is the previous post in case people missed it - 555 Flyback Driver and Plasma Speaker Part I

I'm missing a couple of key components so I haven't been able to fully test the circuit. Here are some photos of the PCB being constructed:
The design transferred to the copper clad board
The etched PCB before removing the toner ink


The next part to be getting on with whilst waiting for parts is to design an enclosure for the high voltage part.  I don't want anyone to be able to touch the arc but I also want to try to cause the sound to resonate so it can be heard.  I'm basically going to design a speaker enclosure without a paper speaker cone.

I could design and print an enclosure using a 3D printer but I prefer to laser cut enclosures because it's quicker and I personally really like the wood finish.  Don't worry only the high voltage arc will not be exposed to the wood - that would be bad and would cause charring and fire!

I sketched up a quick idea on a piece of paper which purely shows the kind of thing I'm looking for.

Simple enclosure Idea for Plasma Speaker
From there I went to Inkscape and using the tabbed box maker extension I created a 72 x 72 x 72 mm square box.  My plan is mount the HV probes in the box with a mirrored acrylic behind the probes to maximise the arc from a purely aesthetic view point with a wooden case all made with on a laser cutter and glued together.  From Inkscape I exported the files in DXF format into solidworks so that I can render them in 3D and so that I can add holes and other features.  I prefer to work in solidworks when designing enclosures.

Here is what I came up with eventually.  I also designed some holders for the HV probes which I'm going to 3D print.  I'm hoping everything will work out ok!
Plasma Speaker Assembly - ISO view

Plasma Speaker Assembly Front View



HV Probe Holder


HV Probe Holder - Side View

HV Probe Holder - Top View
What I need to do now is get all of these parts laser cut and 3D printed and get on with assembly.

That's all for now - Langster

]]>
555 Flyback Driver and Plasma Speaker Part II http://langster1980.blogspot.com/2016/02/555-flyback-driver-and-plasma-speaker_9.html Tue, 09 Feb 2016 22:56:00 +0000 https://hacman.org.uk/?guid=7b9cc97d7bd8ed8f73b90bc84d7bf12c
The design transferred to the copper clad board
The etched PCB before removing the toner ink


The next part to be getting on with whilst waiting for parts is to design an enclosure for the high voltage part.  I don't want anyone to be able to touch the arc but I also want to try to cause the sound to resonate so it can be hear.  I'm basically going to design a speaker enclosure without a paper speaker cone.

I could design and print an enclosure using a 3D printer but I prefer to laser cut enclosures because it's quicker and I personally really like the wood finish.  Don't worry only the high voltage arc will not be exposed to the wood - that would be bad and would case charring and fire!

I sketched up a quick idea on a piece of paper which purely shows the kind of thing I'm looking for.

Simple enclosure Idea for Plasma Speaker
From there I went to Inkscape and using the tabbed box maker extension I created a 72 x 72 x 72 mm square box.  My plan is mount the HV probes in the box with a mirrored acrylic behind the probes to maximise the arc from a purely aesthetic view point with a wooden case all made with on a laser cutter and glued together.  From Inkscape I exported the files in DXF format into solidworks so that I can render them in 3D and so that I can add holes and other features.  I prefer to work in solidworks when designing enclosures.

Here is what I came up with eventually.  I also designed some holders for the HV probes which I'm going to 3D print.  I'm hoping everything will work out ok!
Plasma Speaker Assembly - ISO view

Plasma Speaker Assembly Front View



HV Probe Holder


HV Probe Holder - Side View

HV Probe Holder - Top View


What I need to do now is get all of these parts laser cut and 3D printed and get on with assembly. 

That's all for now - Langster

]]>
The Maker Fairies are going to Newcastle! https://hacman.org.uk/the-maker-fairies-are-going-to-newcastle/ Sun, 07 Feb 2016 23:48:09 +0000 https://hacman.org.uk/?p=4301 HacMan, LaMM and a couple of members of Swindon Makerspace are going to UK Maker Faire at the Life Science Centre in Newcastle. Here’s a sneak preview of what we will be taking with us:

Jake Causier : Orange Star Light Tank (from the Nintendo game Advance Wars)

Mounted on an old electric wheelchair purchased from eBay, Jake’s tank is constructed from a wooden frame clad with foamboard sheets to form armour. The whole thing is large enough for a medium sized adult to fit inside, although the seating position is less than ideal. The finished project will also have functioning LED headlamps, feature laser-cut details, and be capable of a top speed of around 10 – 12mph.

Jake's tank: progress image

This is the the current state of Jake’s tank. It will be finished, he promises.

This is the tank Jake is basing his cosplay on.

This is the tank Jake is basing his cosplay on.

Project page: http://micnax.tumblr.com/tagged/advance-wars

Skippy McGaw : K9

Skippy is building a replica of K-9 from Dr Who. The body design is based on Dave Everett’s design (K9 Builders Club), instead of producing it out of foamboard however, Skippy is laser cutting it from 3mm MDF. The replica will be driven using custom built motor controllers driving off the shelf motors taken from balance boards, sensor control is achieved via a mixture of Arduino and Raspberry Pi and remote control is provided via a captive wifi portal running a custom interface.

K-9

K-9

Project page: https://skippy.org.uk/projects/remote-control-k-9-from-doctor-who/

Tamarisk Kay : Bat Goggles

Designed to allow school children to better understand how bats navigate these steampunk-esque goggles deliberately obstruct the wearers vision forcing them to rely on feedback from an ultrasonic module attached to the front of the goggles. As humans are awful at interpreting ultrasonic signals, an Arduino is used to translate the distance response into audible beeps (or vibrations) which get closer together as the wearer gets closer to an object. The ears themselves are merely for decoration.

Wa-na-na-na bat goggles!

Wa-na-na-na bat goggles!

Project page: to be created

Bob Clough, Chris Hilliard & Tamarisk Kay : Bugzilla

5 times the size of a standard BUG! Bugzilla was first created as part of our stand decorations for Liverpool MakeFest 2015. Unlike the standard BUGS! which are fundamentally a laser cut case for an LED throwie, Bugzilla is a touch more complicated. The “LED” eyes are 3D printed cases containing Neopixel Jewels which are controlled by an Arduino hidden under the “coin cell” on her back. Bugzilla is made out of 3mm laser ply from Kitronik, lovingly laminated using wood glue, and painstakingly hand-sanded to create a smooth edge by Chris. Once completed she was treated with several coats of Danish Oil.

Bugzilla

Bugzilla

Project page: to be created

SNHack: Twitter Teletype

This is a vintage ASR-33 Teletype, circa 1963-1981 (but the heyday of them ended in approx 1975). It’s been restored to working (if not wonderful) condition, stripped of it’s outer case so you can see it’s (wonderful) insides, and attached to a raspberry pi and some other gubbins in order to type out tweets – as you can see for yourself if you mention @snhack.

twitter_teletype

twitter_teletype

Project page: https://github.com/snhack/snhack.github.io/wiki/Twitter-to-Teletype

Ruth Abbott: Wooden Wallets and other impractical curio

Created using laser cut solid wood, beeswax and lots and lots of sanding Ruth creates wooden wallets, heat bent bangles and copper cuff links laser etched with your own handwriting. All of her items are sold online and she loves to pair vintage items like letterpress slugs with the exactness of laser cut materials She will be bringing a selection of her creations to show that when creating art with laser cutters it’s easy to move beyond the often 2 dimensional examples on the high street.

Wooden wallet

Wooden wallet

Project page: www.omgoshshop.etsy.com

]]>
555 Flyback Driver and Plasma Speaker http://langster1980.blogspot.com/2016/02/555-flyback-driver-and-plasma-speaker.html Sun, 07 Feb 2016 00:44:00 +0000 https://hacman.org.uk/?guid=ad7ed8fad3c820647816073f4a0a4300
WARNING - This is a High Voltage circuit!  Using Flyback transformers without due care and attention is DANGEROUS. Lethal voltage and current is present when operating this circuit.  The author is not responsible for anything which occurs by constructing or operating this circuit!

There are lots of tutorials and videos on YouTube and Instructables about this subject.  I used the site below as my inspiration:

http://www.instructables.com/id/Audio-modulated-flyback-transformer-driver/?ALLSTEPS

Here is the schematic diagram for the circuit:


The circuit is fairly simple in operation.  Power is supplied via a standard 12 Vdc 5 amp power supply via the DC barrel socket or via the 5 mm screw terminal JP1.  The 12 volt supply is smoothed by the 100 uF and 100 nF capacitors.

The main part of the circuit is made up of a 555 timer in astable mode.  Astable means there will be a constantly repeating 12 volt peak square present at pin 3.  The frequency of the square wave is set by the 50 k potentiometer RV1.  The mark space ratio of the square wave (the width of each pulse and the gap between each pulse) is set by the 50 k potentiometer RV2.  The output at pin 3 is used to drive two bipolar transistors which in turn drive a high current, high voltage N-type MOSFET.  The MOSFET will drive a flyback transformer which will have it's output at the secondary spaced so as to draw a high voltage arc.  The flyback transformer will be connected externally via the 5 mm screw terminal JP3.

The audio signal for the plasma speaker will be coupled to the circuit via the 5 mm screw terminal JP2.  This will take in a standard audio signal either from an audio amplifier or directly from an audio source such as an MP3 player or a signal generator - I haven't decided yet!

To make things easy for me and to ensure this circuit works as intended I simulated the circuit first. It works perfectly well.  The voltage generated by flyback transformer at the secondary should be around 1.7 kV assuming I have guessed at the turns ratio of the flyback transformer correctly.

I then designed a printed circuit board for the circuit.  I find it much easier to lay circuit boards out than to use stripboard to create circuits however stripboard would work perfectly well.

Here is the PCB layout:

Plasma Speaker Top Layer
Plasma Speaker Bottom Layer
Both layers with dimensions
In designing this layout I was trying to make the circuit as small as possible but still use through hole components.  I find it much easier to work with through hole components when prototyping.  If I was going to make more of these circuits I would design with surface mount components and reduce the size to less than 50 mm x 50 mm.  This way I can get PCBS made for a reasonable price in China by Elecrow.

Just for fun I've rendered the circuit in 3D using Sketchup so that I can visualise how the circuit will look once it is complete.  It also means I can spot any potential construction and layout issues before I etch and populate the PCB.

Isometric Render of populated Plasma Speaker PCB
Top View of Plasma Speaker PCB
In order to populate the PCB the following components will be required:

Part Value Description Vendor Part Number Cost (£)

C1 10 nF Ceramic Capacitor Farnell 1141772 0.0851
C2 100 nF Ceramic Capacitor Farnell 1141775 0.0721
C3 220 nF Ceramic Capacitor Farnell 2395774 0.132
C4 100 nF Ceramic Capacitor Farnell 1141775 0.0721
C5 100 uF Electrolytic Capacitor Farnell 2346578 0.1178
D1 UF4007 High Speed Diode Farnell 4085310 0.372
IC1 ICM7555 CMOS 555 timer Farnell 9488243 0.528
J1 n/a 2.5mm DC barrel Jack Farnell 1737246 0.469
JP1 n/a 5mm Screw terminal Farnell 2493614 0.16
JP2 n/a 5mm Screw terminal Farnell 2493614 0.16
JP3 n/a 5mm Screw terminal Farnell 2493614 0.16
JP4 Jumper 2 pin header Farnell 3418285 0.27
KK1 SK104 Heatsink TO247 Heatsink Farnell 1892329 1.06
Q1 BC549 TO92 NPN Transistor Farnell 2453797 0.232
Q2 BC559 TO92 PNP Transistor Farnell 2453808 0.232
Q3 IRFP250 TO247 High Power MOSFET Farnell 8649260 1.26
R1 270 Ohms ¼ Watt Carbon film Resistor Farnell 9339353 0.0356
R2 22 Ohms 1 Watt Carbon Film Resistor Farnell 1565366 0.0664
R3 150 Ohms 1 Watt Carbon Film Resistor Farnell 1565346 0.0664
RV1 100 k-Ohms ALPS PCB mount Potentiometer Farnell 1191742 1.28
RV2 100 k-Ohms ALPS PCB mount Potentiometer Farnell 1191742 1.28

The total cost of components, not including the PCB or flyback transformer will be:

£8.12

Flyback transformers can be very easily sourced from old televisions, junk shops and everyone's favourite online auction site:

Ebay - Flyback Transformer

They are currently on sale for £7.81 - I remember them being cheaper but they are becoming more rare!

I'm guessing at the cost of making and etching a PCB for this project at £3.00

That brings the total cost to £18.93

Not bad I suppose...I'll probably etch and populate a PCB and test the circuit in the next post.  That's all for now

Take care people - Langster!]]>

WARNING - This is a High Voltage circuit!  Using Flyback transformers without due care and attention is DANGEROUS. Lethal voltage and current is present when operating this circuit.  The author is not responsible for anything which occurs by constructing or operating this circuit!

There are lots of tutorials and videos on YouTube and Instructables about this subject.  I used the site below as my inspiration:

http://www.instructables.com/id/Audio-modulated-flyback-transformer-driver/?ALLSTEPS

Here is the schematic diagram for the circuit:


The circuit is fairly simple in operation.  Power is supplied via a standard 12 Vdc 5 amp power supply via the DC barrel socket or via the 5 mm screw terminal JP1.  The 12 volt supply is smoothed by the 100 uF and 100 nF capacitors.

The main part of the circuit is made up of a 555 timer in astable mode.  Astable means there will be a constantly repeating 12 volt peak square present at pin 3.  The frequency of the square wave is set by the 50 k potentiometer RV1.  The mark space ratio of the square wave (the width of each pulse and the gap between each pulse) is set by the 50 k potentiometer RV2.  The output at pin 3 is used to drive two bipolar transistors which in turn drive a high current, high voltage N-type MOSFET.  The MOSFET will drive a flyback transformer which will have it's output at the secondary spaced so as to draw a high voltage arc.  The flyback transformer will be connected externally via the 5 mm screw terminal JP3.

The audio signal for the plasma speaker will be coupled to the circuit via the 5 mm screw terminal JP2.  This will take in a standard audio signal either from an audio amplifier or directly from an audio source such as an MP3 player or a signal generator - I haven't decided yet!

To make things easy for me and to ensure this circuit works as intended I simulated the circuit first. It works perfectly well.  The voltage generated by flyback transformer at the secondary should be around 1.7 kV assuming I have guessed at the turns ratio of the flyback transformer correctly.

I then designed a printed circuit board for the circuit.  I find it much easier to lay circuit boards out than to use stripboard to create circuits however stripboard would work perfectly well.

Here is the PCB layout:

Plasma Speaker Top Layer
Plasma Speaker Bottom Layer
Both layers with dimensions
In designing this layout I was trying to make the circuit as small as possible but still use through hole components.  I find it much easier to work with through hole components when prototyping.  If I was going to make more of these circuits I would design with surface mount components and reduce the size to less than 50 mm x 50 mm.  This way I can get PCBS made for a reasonable price in China by Elecrow.

Just for fun I've rendered the circuit in 3D using Sketchup so that I can visualise how the circuit will look once it is complete.  It also means I can spot any potential construction and layout issues before I etch and populate the PCB.

Isometric Render of populated Plasma Speaker PCB
Top View of Plasma Speaker PCB
In order to populate the PCB the following components will be required:

Part Value Description Vendor Part Number Cost (£)

C1 10 nF Ceramic Capacitor Farnell 1141772 0.0851
C2 100 nF Ceramic Capacitor Farnell 1141775 0.0721
C3 220 nF Ceramic Capacitor Farnell 2395774 0.132
C4 100 nF Ceramic Capacitor Farnell 1141775 0.0721
C5 100 uF Electrolytic Capacitor Farnell 2346578 0.1178
D1 UF4007 High Speed Diode Farnell 4085310 0.372
IC1 ICM7555 CMOS 555 timer Farnell 9488243 0.528
J1 n/a 2.5mm DC barrel Jack Farnell 1737246 0.469
JP1 n/a 5mm Screw terminal Farnell 2493614 0.16
JP2 n/a 5mm Screw terminal Farnell 2493614 0.16
JP3 n/a 5mm Screw terminal Farnell 2493614 0.16
JP4 Jumper 2 pin header Farnell 3418285 0.27
KK1 SK104 Heatsink TO247 Heatsink Farnell 1892329 1.06
Q1 BC549 TO92 NPN Transistor Farnell 2453797 0.232
Q2 BC559 TO92 PNP Transistor Farnell 2453808 0.232
Q3 IRFP250 TO247 High Power MOSFET Farnell 8649260 1.26
R1 270 Ohms ¼ Watt Carbon film Resistor Farnell 9339353 0.0356
R2 22 Ohms 1 Watt Carbon Film Resistor Farnell 1565366 0.0664
R3 150 Ohms 1 Watt Carbon Film Resistor Farnell 1565346 0.0664
RV1 100 k-Ohms ALPS PCB mount Potentiometer Farnell 1191742 1.28
RV2 100 k-Ohms ALPS PCB mount Potentiometer Farnell 1191742 1.28

The total cost of components, not including the PCB or flyback transformer will be:

£8.12

Flyback transformers can be very easily sourced from old televisions, junk shops and everyone's favourite online auction site:

Ebay - Flyback Transformer

They are currently on sale for £7.81 - I remember them being cheaper but they are becoming more rare!

I'm guessing at the cost of making and etching a PCB for this project at £3.00

That brings the total cost to £18.93

Not bad I suppose...I'll probably etch and populate a PCB and test the circuit in the next post.  That's all for now

Take care people - Langster!]]>
555 Flyback Driver and Plasma Speaker http://langster1980.blogspot.com/2016/02/555-flyback-driver-and-plasma-speaker.html Sun, 07 Feb 2016 00:44:00 +0000 https://hacman.org.uk/?guid=ad7ed8fad3c820647816073f4a0a4300
WARNING - This is a High Voltage circuit!  Using Flyback transformers without due care and attention is DANGEROUS. Lethal voltage and current is present when operating this circuit.  The author is not responsible for anything which occurs by constructing or operating this circuit!

There are lots of tutorials and videos on YouTube and Instructables about this subject.  I used the site below as my inspiration:

http://www.instructables.com/id/Audio-modulated-flyback-transformer-driver/?ALLSTEPS

Here is the schematic diagram for the circuit:


The circuit is fairly simple in operation.  Power is supplied via a standard 12 Vdc 5 amp power supply via the DC barrel socket or via the 5 mm screw terminal JP1.  The 12 volt supply is smoothed by the 100 uF and 100 nF capacitors.

The main part of the circuit is made up of a 555 timer in astable mode.  Astable means there will be a constantly repeating 12 volt peak square present at pin 3.  The frequency of the square wave is set by the 50 k potentiometer RV1.  The mark space ratio of the square wave (the width of each pulse and the gap between each pulse) is set by the 50 k potentiometer RV2.  The output at pin 3 is used to drive two bipolar transistors which in turn drive a high current, high voltage N-type MOSFET.  The MOSFET will drive a flyback transformer which will have it's output at the secondary spaced so as to draw a high voltage arc.  The flyback transformer will be connected externally via the 5 mm screw terminal JP3.

The audio signal for the plasma speaker will be coupled to the circuit via the 5 mm screw terminal JP2.  This will take in a standard audio signal either from an audio amplifier or directly from an audio source such as an MP3 player or a signal generator - I haven't decided yet!

To make things easy for me and to ensure this circuit works as intended I simulated the circuit first. It works perfectly well.  The voltage generated by flyback transformer at the secondary should be around 1.7 kV assuming I have guessed at the turns ratio of the flyback transformer correctly.

I then designed a printed circuit board for the circuit.  I find it much easier to lay circuit boards out than to use stripboard to create circuits however stripboard would work perfectly well.

Here is the PCB layout:

Plasma Speaker Top Layer
Plasma Speaker Bottom Layer
Both layers with dimensions
In designing this layout I was trying to make the circuit as small as possible but still use through hole components.  I find it much easier to work with through hole components when prototyping.  If I was going to make more of these circuits I would design with surface mount components and reduce the size to less than 50 mm x 50 mm.  This way I can get PCBS made for a reasonable price in China by Elecrow.

Just for fun I've rendered the circuit in 3D using Sketchup so that I can visualise how the circuit will look once it is complete.  It also means I can spot any potential construction and layout issues before I etch and populate the PCB.

Isometric Render of populated Plasma Speaker PCB
Top View of Plasma Speaker PCB
In order to populate the PCB the following components will be required:

Part Value Description Vendor Part Number Cost (£)

C1 10 nF Ceramic Capacitor Farnell 1141772 0.0851
C2 100 nF Ceramic Capacitor Farnell 1141775 0.0721
C3 220 nF Ceramic Capacitor Farnell 2395774 0.132
C4 100 nF Ceramic Capacitor Farnell 1141775 0.0721
C5 100 uF Electrolytic Capacitor Farnell 2346578 0.1178
D1 UF4007 High Speed Diode Farnell 4085310 0.372
IC1 ICM7555 CMOS 555 timer Farnell 9488243 0.528
J1 n/a 2.5mm DC barrel Jack Farnell 1737246 0.469
JP1 n/a 5mm Screw terminal Farnell 2493614 0.16
JP2 n/a 5mm Screw terminal Farnell 2493614 0.16
JP3 n/a 5mm Screw terminal Farnell 2493614 0.16
JP4 Jumper 2 pin header Farnell 3418285 0.27
KK1 SK104 Heatsink TO247 Heatsink Farnell 1892329 1.06
Q1 BC549 TO92 NPN Transistor Farnell 2453797 0.232
Q2 BC559 TO92 PNP Transistor Farnell 2453808 0.232
Q3 IRFP250 TO247 High Power MOSFET Farnell 8649260 1.26
R1 270 Ohms ¼ Watt Carbon film Resistor Farnell 9339353 0.0356
R2 22 Ohms 1 Watt Carbon Film Resistor Farnell 1565366 0.0664
R3 150 Ohms 1 Watt Carbon Film Resistor Farnell 1565346 0.0664
RV1 100 k-Ohms ALPS PCB mount Potentiometer Farnell 1191742 1.28
RV2 100 k-Ohms ALPS PCB mount Potentiometer Farnell 1191742 1.28

The total cost of components, not including the PCB or flyback transformer will be:

£8.12

Flyback transformers can be very easily sourced from old televisions, junk shops and everyone's favourite online auction site:

Ebay - Flyback Transformer

They are currently on sale for £7.81 - I remember them being cheaper but they are becoming more rare!

I'm guessing at the cost of making and etching a PCB for this project at £3.00

That brings the total cost to £18.93

Not bad I suppose...I'll probably etch and populate a PCB and test the circuit in the next post.  That's all for now

Take care people - Langster!]]>

WARNING - This is a High Voltage circuit!  Using Flyback transformers without due care and attention is DANGEROUS. Lethal voltage and current is present when operating this circuit.  The author is not responsible for anything which occurs by constructing or operating this circuit!

There are lots of tutorials and videos on YouTube and Instructables about this subject.  I used the site below as my inspiration:

http://www.instructables.com/id/Audio-modulated-flyback-transformer-driver/?ALLSTEPS

Here is the schematic diagram for the circuit:


The circuit is fairly simple in operation.  Power is supplied via a standard 12 Vdc 5 amp power supply via the DC barrel socket or via the 5 mm screw terminal JP1.  The 12 volt supply is smoothed by the 100 uF and 100 nF capacitors.

The main part of the circuit is made up of a 555 timer in astable mode.  Astable means there will be a constantly repeating 12 volt peak square present at pin 3.  The frequency of the square wave is set by the 50 k potentiometer RV1.  The mark space ratio of the square wave (the width of each pulse and the gap between each pulse) is set by the 50 k potentiometer RV2.  The output at pin 3 is used to drive two bipolar transistors which in turn drive a high current, high voltage N-type MOSFET.  The MOSFET will drive a flyback transformer which will have it's output at the secondary spaced so as to draw a high voltage arc.  The flyback transformer will be connected externally via the 5 mm screw terminal JP3.

The audio signal for the plasma speaker will be coupled to the circuit via the 5 mm screw terminal JP2.  This will take in a standard audio signal either from an audio amplifier or directly from an audio source such as an MP3 player or a signal generator - I haven't decided yet!

To make things easy for me and to ensure this circuit works as intended I simulated the circuit first. It works perfectly well.  The voltage generated by flyback transformer at the secondary should be around 1.7 kV assuming I have guessed at the turns ratio of the flyback transformer correctly.

I then designed a printed circuit board for the circuit.  I find it much easier to lay circuit boards out than to use stripboard to create circuits however stripboard would work perfectly well.

Here is the PCB layout:

Plasma Speaker Top Layer
Plasma Speaker Bottom Layer
Both layers with dimensions
In designing this layout I was trying to make the circuit as small as possible but still use through hole components.  I find it much easier to work with through hole components when prototyping.  If I was going to make more of these circuits I would design with surface mount components and reduce the size to less than 50 mm x 50 mm.  This way I can get PCBS made for a reasonable price in China by Elecrow.

Just for fun I've rendered the circuit in 3D using Sketchup so that I can visualise how the circuit will look once it is complete.  It also means I can spot any potential construction and layout issues before I etch and populate the PCB.

Isometric Render of populated Plasma Speaker PCB
Top View of Plasma Speaker PCB
In order to populate the PCB the following components will be required:

Part Value Description Vendor Part Number Cost (£)

C1 10 nF Ceramic Capacitor Farnell 1141772 0.0851
C2 100 nF Ceramic Capacitor Farnell 1141775 0.0721
C3 220 nF Ceramic Capacitor Farnell 2395774 0.132
C4 100 nF Ceramic Capacitor Farnell 1141775 0.0721
C5 100 uF Electrolytic Capacitor Farnell 2346578 0.1178
D1 UF4007 High Speed Diode Farnell 4085310 0.372
IC1 ICM7555 CMOS 555 timer Farnell 9488243 0.528
J1 n/a 2.5mm DC barrel Jack Farnell 1737246 0.469
JP1 n/a 5mm Screw terminal Farnell 2493614 0.16
JP2 n/a 5mm Screw terminal Farnell 2493614 0.16
JP3 n/a 5mm Screw terminal Farnell 2493614 0.16
JP4 Jumper 2 pin header Farnell 3418285 0.27
KK1 SK104 Heatsink TO247 Heatsink Farnell 1892329 1.06
Q1 BC549 TO92 NPN Transistor Farnell 2453797 0.232
Q2 BC559 TO92 PNP Transistor Farnell 2453808 0.232
Q3 IRFP250 TO247 High Power MOSFET Farnell 8649260 1.26
R1 270 Ohms ¼ Watt Carbon film Resistor Farnell 9339353 0.0356
R2 22 Ohms 1 Watt Carbon Film Resistor Farnell 1565366 0.0664
R3 150 Ohms 1 Watt Carbon Film Resistor Farnell 1565346 0.0664
RV1 100 k-Ohms ALPS PCB mount Potentiometer Farnell 1191742 1.28
RV2 100 k-Ohms ALPS PCB mount Potentiometer Farnell 1191742 1.28

The total cost of components, not including the PCB or flyback transformer will be:

£8.12

Flyback transformers can be very easily sourced from old televisions, junk shops and everyone's favourite online auction site:

Ebay - Flyback Transformer

They are currently on sale for £7.81 - I remember them being cheaper but they are becoming more rare!

I'm guessing at the cost of making and etching a PCB for this project at £3.00

That brings the total cost to £18.93

Not bad I suppose...I'll probably etch and populate a PCB and test the circuit in the next post.  That's all for now

Take care people - Langster!]]>
555 Flyback Driver and Plasma Speaker http://langster1980.blogspot.com/2016/02/555-flyback-driver-and-plasma-speaker.html Sun, 07 Feb 2016 00:44:00 +0000 https://hacman.org.uk/?guid=ad7ed8fad3c820647816073f4a0a4300
WARNING - This is a High Voltage circuit!  Using Flyback transformers without due care and attention is DANGEROUS. Lethal voltage and current is present when operating this circuit.  The author is not responsible for anything which occurs by constructing or operating this circuit!

There are lots of tutorials and videos on YouTube and Instructables about this subject.  I used the site below as my inspiration:

http://www.instructables.com/id/Audio-modulated-flyback-transformer-driver/?ALLSTEPS

Here is the schematic diagram for the circuit:


The circuit is fairly simple in operation.  Power is supplied via a standard 12 Vdc 5 amp power supply via the DC barrel socket or via the 5 mm screw terminal JP1.  The 12 volt supply is smoothed by the 100 uF and 100 nF capacitors.

The main part of the circuit is made up of a 555 timer in astable mode.  Astable means there will be a constantly repeating 12 volt peak square present at pin 3.  The frequency of the square wave is set by the 50 k potentiometer RV1.  The mark space ratio of the square wave (the width of each pulse and the gap between each pulse) is set by the 50 k potentiometer RV2.  The output at pin 3 is used to drive two bipolar transistors which in turn drive a high current, high voltage N-type MOSFET.  The MOSFET will drive a flyback transformer which will have it's output at the secondary spaced so as to draw a high voltage arc.  The flyback transformer will be connected externally via the 5 mm screw terminal JP3.

The audio signal for the plasma speaker will be coupled to the circuit via the 5 mm screw terminal JP2.  This will take in a standard audio signal either from an audio amplifier or directly from an audio source such as an MP3 player or a signal generator - I haven't decided yet!

To make things easy for me and to ensure this circuit works as intended I simulated the circuit first. It works perfectly well.  The voltage generated by flyback transformer at the secondary should be around 1.7 kV assuming I have guessed at the turns ratio of the flyback transformer correctly.

I then designed a printed circuit board for the circuit.  I find it much easier to lay circuit boards out than to use stripboard to create circuits however stripboard would work perfectly well.

Here is the PCB layout:

Plasma Speaker Top Layer
Plasma Speaker Bottom Layer
Both layers with dimensions
In designing this layout I was trying to make the circuit as small as possible but still use through hole components.  I find it much easier to work with through hole components when prototyping.  If I was going to make more of these circuits I would design with surface mount components and reduce the size to less than 50 mm x 50 mm.  This way I can get PCBS made for a reasonable price in China by Elecrow.

Just for fun I've rendered the circuit in 3D using Sketchup so that I can visualise how the circuit will look once it is complete.  It also means I can spot any potential construction and layout issues before I etch and populate the PCB.

Isometric Render of populated Plasma Speaker PCB
Top View of Plasma Speaker PCB
In order to populate the PCB the following components will be required:

Part Value Description Vendor Part Number Cost (£)

C1 10 nF Ceramic Capacitor Farnell 1141772 0.0851
C2 100 nF Ceramic Capacitor Farnell 1141775 0.0721
C3 220 nF Ceramic Capacitor Farnell 2395774 0.132
C4 100 nF Ceramic Capacitor Farnell 1141775 0.0721
C5 100 uF Electrolytic Capacitor Farnell 2346578 0.1178
D1 UF4007 High Speed Diode Farnell 4085310 0.372
IC1 ICM7555 CMOS 555 timer Farnell 9488243 0.528
J1 n/a 2.5mm DC barrel Jack Farnell 1737246 0.469
JP1 n/a 5mm Screw terminal Farnell 2493614 0.16
JP2 n/a 5mm Screw terminal Farnell 2493614 0.16
JP3 n/a 5mm Screw terminal Farnell 2493614 0.16
JP4 Jumper 2 pin header Farnell 3418285 0.27
KK1 SK104 Heatsink TO247 Heatsink Farnell 1892329 1.06
Q1 BC549 TO92 NPN Transistor Farnell 2453797 0.232
Q2 BC559 TO92 PNP Transistor Farnell 2453808 0.232
Q3 IRFP250 TO247 High Power MOSFET Farnell 8649260 1.26
R1 270 Ohms ¼ Watt Carbon film Resistor Farnell 9339353 0.0356
R2 22 Ohms 1 Watt Carbon Film Resistor Farnell 1565366 0.0664
R3 150 Ohms 1 Watt Carbon Film Resistor Farnell 1565346 0.0664
RV1 100 k-Ohms ALPS PCB mount Potentiometer Farnell 1191742 1.28
RV2 100 k-Ohms ALPS PCB mount Potentiometer Farnell 1191742 1.28

The total cost of components, not including the PCB or flyback transformer will be:

£8.12

Flyback transformers can be very easily sourced from old televisions, junk shops and everyone's favourite online auction site:

Ebay - Flyback Transformer

They are currently on sale for £7.81 - I remember them being cheaper but they are becoming more rare!

I'm guessing at the cost of making and etching a PCB for this project at £3.00

That brings the total cost to £18.93

Not bad I suppose...I'll probably etch and populate a PCB and test the circuit in the next post.  That's all for now

Take care people - Langster!]]>

WARNING - This is a High Voltage circuit!  Using Flyback transformers without due care and attention is DANGEROUS. Lethal voltage and current is present when operating this circuit.  The author is not responsible for anything which occurs by constructing or operating this circuit!

There are lots of tutorials and videos on YouTube and Instructables about this subject.  I used the site below as my inspiration:

http://www.instructables.com/id/Audio-modulated-flyback-transformer-driver/?ALLSTEPS

Here is the schematic diagram for the circuit:


The circuit is fairly simple in operation.  Power is supplied via a standard 12 Vdc 5 amp power supply via the DC barrel socket or via the 5 mm screw terminal JP1.  The 12 volt supply is smoothed by the 100 uF and 100 nF capacitors.

The main part of the circuit is made up of a 555 timer in astable mode.  Astable means there will be a constantly repeating 12 volt peak square present at pin 3.  The frequency of the square wave is set by the 50 k potentiometer RV1.  The mark space ratio of the square wave (the width of each pulse and the gap between each pulse) is set by the 50 k potentiometer RV2.  The output at pin 3 is used to drive two bipolar transistors which in turn drive a high current, high voltage N-type MOSFET.  The MOSFET will drive a flyback transformer which will have it's output at the secondary spaced so as to draw a high voltage arc.  The flyback transformer will be connected externally via the 5 mm screw terminal JP3.

The audio signal for the plasma speaker will be coupled to the circuit via the 5 mm screw terminal JP2.  This will take in a standard audio signal either from an audio amplifier or directly from an audio source such as an MP3 player or a signal generator - I haven't decided yet!

To make things easy for me and to ensure this circuit works as intended I simulated the circuit first. It works perfectly well.  The voltage generated by flyback transformer at the secondary should be around 1.7 kV assuming I have guessed at the turns ratio of the flyback transformer correctly.

I then designed a printed circuit board for the circuit.  I find it much easier to lay circuit boards out than to use stripboard to create circuits however stripboard would work perfectly well.

Here is the PCB layout:

Plasma Speaker Top Layer
Plasma Speaker Bottom Layer
Both layers with dimensions
In designing this layout I was trying to make the circuit as small as possible but still use through hole components.  I find it much easier to work with through hole components when prototyping.  If I was going to make more of these circuits I would design with surface mount components and reduce the size to less than 50 mm x 50 mm.  This way I can get PCBS made for a reasonable price in China by Elecrow.

Just for fun I've rendered the circuit in 3D using Sketchup so that I can visualise how the circuit will look once it is complete.  It also means I can spot any potential construction and layout issues before I etch and populate the PCB.

Isometric Render of populated Plasma Speaker PCB
Top View of Plasma Speaker PCB
In order to populate the PCB the following components will be required:

Part Value Description Vendor Part Number Cost (£)

C1 10 nF Ceramic Capacitor Farnell 1141772 0.0851
C2 100 nF Ceramic Capacitor Farnell 1141775 0.0721
C3 220 nF Ceramic Capacitor Farnell 2395774 0.132
C4 100 nF Ceramic Capacitor Farnell 1141775 0.0721
C5 100 uF Electrolytic Capacitor Farnell 2346578 0.1178
D1 UF4007 High Speed Diode Farnell 4085310 0.372
IC1 ICM7555 CMOS 555 timer Farnell 9488243 0.528
J1 n/a 2.5mm DC barrel Jack Farnell 1737246 0.469
JP1 n/a 5mm Screw terminal Farnell 2493614 0.16
JP2 n/a 5mm Screw terminal Farnell 2493614 0.16
JP3 n/a 5mm Screw terminal Farnell 2493614 0.16
JP4 Jumper 2 pin header Farnell 3418285 0.27
KK1 SK104 Heatsink TO247 Heatsink Farnell 1892329 1.06
Q1 BC549 TO92 NPN Transistor Farnell 2453797 0.232
Q2 BC559 TO92 PNP Transistor Farnell 2453808 0.232
Q3 IRFP250 TO247 High Power MOSFET Farnell 8649260 1.26
R1 270 Ohms ¼ Watt Carbon film Resistor Farnell 9339353 0.0356
R2 22 Ohms 1 Watt Carbon Film Resistor Farnell 1565366 0.0664
R3 150 Ohms 1 Watt Carbon Film Resistor Farnell 1565346 0.0664
RV1 100 k-Ohms ALPS PCB mount Potentiometer Farnell 1191742 1.28
RV2 100 k-Ohms ALPS PCB mount Potentiometer Farnell 1191742 1.28

The total cost of components, not including the PCB or flyback transformer will be:

£8.12

Flyback transformers can be very easily sourced from old televisions, junk shops and everyone's favourite online auction site:

Ebay - Flyback Transformer

They are currently on sale for £7.81 - I remember them being cheaper but they are becoming more rare!

I'm guessing at the cost of making and etching a PCB for this project at £3.00

That brings the total cost to £18.93

Not bad I suppose...I'll probably etch and populate a PCB and test the circuit in the next post.  That's all for now

Take care people - Langster!]]>