Intro: Plasma Speaker on the Cheap
In these instructables, we are going to show you how to make cheap plasma speaker with nice looking housing. We made one before, but it was on breadboard, so we decided to remake it a little bit.
We found circuit on this site. We remake it a little bit, adding flyback diode, and left / right input switch. But our goal was to make cheap, portable and nice looking housing.
What is plasma speaker?
Plasma speaker is special speaker, which is using electrical spark to generate sound.
Step 1: Circuit
As we said before we remade this circuit. To protect whole circuit we added fuse (around 10A). Next, we added switch wich is used to select input chanel (left or right). Because of flyback curent we added "flyback diode".
Components you need:
- Audio connector ________________(1) .... (Picture 2)
- 2,2 uF Electrolytic Capacitor_______(1)
- 10k ohm (potentiometer)__________(1)
- 2,2k ohm resistor________________(1)
- 10 ohm resistor_________________(1)
- 0,1u F ceramic capacitor__________(2)
- 3,3n F ceramic capacitor__________(1)
- SG 3525 (buy more than one)______(1)
- UF4007 Fast diode_______________(3)
- Fuse (10A)_____________________(1)
- Flyback transformer______________(1)
Picture 3 = circuit
Step 2: Flyback Transformer
You can find flyback transformer in old cathode TVs. It is located on its circuit board.
To desolder it, firs heat tin, then when it is heated blow it away with high presure air. Repeate these for all pins of transformer.
Then solder first elektrode as it is shown on picture, then isolate it.
If you have isolate paper, wrap it around transformer core, as it is shown on pictures. Then make 10 turns with copper wire around it.
Step 3: Housing (1)
We start building our speaker housing with big heat sink, because mosfet will get very hot.
Messures of heat sink (lenght: 200 mm, width: 140 mm, height: 45 mm)
Drill 2 holes in heat sink (look at picture 2), if you don't have hole for mosfet then make one more.
Step 4: Housing (2)
For next step you are going to need:
- M10 screw rod 200 mm (2. pcs)
- M10 washers and nuts
- Wooden planks (140 mm x 200 mm)
First drill 2 holes in planks, same as on heat sink.
Then drill third hole for cables (only in 1 plank, look at picture 2).
You can paint the wooden planks if you want, we painted them in black (picture 3).
Solder wires on mosfet (Lenght of wires about 350 mm) and isolate them (picture 4).
Mount mosfet on the heat sink, use thermally conductive paste, if you have one (picture 5).
When tighten nuts on screw rods, as you can see on picture 6.
Step 5: Housing (3)
In these step you need to organize all components and fix it on plank. We used electrical terminal, as holder for electrodes. We made our electrodes of copper wires and they work well. Dont forget to put heat sink on SG3525 before test.
On picture 4 you can se second electorde of flyback. You can find it with messuring flyback transformer (there are a lot of tutorials on internet) or just try, witch pin will create spark.
When you get spark, you are ready to connect your audio source and test it. You can change output frequency with potentiometer (1,5k ohm works fine).
If you get music you can proceed to next step. If not you have done something wrong.
Step 6: Housing (4)
We decided to make "shell" of plasma speaker out of fibreglass netting mesh, because it is cheap, easy to cut and hot air form the heat sink can easily pass trough it.
Cut fibreglass netting mesh (Picture 2), tape it on speaker to see how it looks, and then sew it with wool. If you chose right colour combination of net and wool it can look pretty cool.
Cut the small window for spark on front side. If you want you can make one out of acrylic glass.
Cut the lines for cables (look at pictures 5 and 6).
Step 7: Conclusion
We cannot run our speaker for more than 1,5 minutes, because mosfet gets very hot. You need to wait few minutes before you use it again so heat sink can cool down.