I have wanted to make a high voltage source for a long time (I mean tens of thousands of volts). Sometimes, at school, we did one with Alfredo “Baldemar” Salas and I always had that little thorn of having been able to do it better… You can do many interesting experiments with them, such as lighting a fluorescent lamp just by touching it.
The particular thing about this project is that I decided to do it only with recycled parts ... well, whenever possible. In this age when everyone says they help the environment, but make the least possible effort, you have to set an example, right?
Well, before continuing it is necessary to clarify that a high voltage source is NOT just any device; high voltages are very dangerous to human health. If the necessary care is not taken they can even cause death; so if the reader has the slightest doubt about its operation, we recommend not trying the present experiment.
Looking for a flyback transformer
Disused or damaged electronic devices are sometimes stored in the company's warehouse, so the idea was to recycle components from a couple of those devices. After searching for a while I found 2 victims: a Samsung SyncMaster 700s CRT monitor and a desktop computer power supply. Both were damaged. What I was interested in finding is a special type of transformer called a flyback, which is used in CRT monitors to generate the necessary high voltage.
Below are photos of the victims.
List of electronic components
After cannibalizing the power supply and monitor I found the following useful components:
- Metal casing
- Flyback High Voltage Transformer
- 2 capacitors of 470uF at 200V
- 1 capacitor 470 uF at 63V
- Bridge rectifier
- Heat dissipator
- Some power transistors J130092 ... in the end I could not use this transistor x that burned me 🙂
- IRF630 mosfet transistor (This was the power transistor I finally used)
- Diode 1N5399
- KA78R12 voltage regulator
- Various capacitors
- Various resistors
After obtaining the loot it was apparent that he needed to purchase a couple of additional components. While the source would not be recycled 100%, the use of new components is minimal.
What I acquired was:
- 1 Transformer with 120V in the primary and in the secondary 12.6-0-12.6 (with central tap)
- 1 NE555 oscillator IC
It all cost me less than $ 14. I also used a couple of components that I had among my things, such as a 50K ohm potentiometer, a 5 ohm resistor at 25 watts, and a quaint two-position switch.
Here is a photo of how the circuitry was arranged inside the case of the power supply.
It should be noted that I did not use the flyback primary but I made my own primary by winding 15 turns of #16 cable over a part of the ferrite core that was exposed. Most flybacks have an exposed core. With 15 laps I was able to generate about 20 thousand volts. With fewer turns, more volts are obtained but more current will circulate in the primary, so a balance must be established between these two parameters because a lot of current can burn the power transistor. For me, 15 laps were enough not to burn it (I am talking about the IRF630).
Here is the schematic diagram for those who dare to build it. I have to clarify that this IS NOT AN OPTIMAL DESIGN. The component values (as well as the components themselves) are not ideal, but rather what I was able to find on the equipment I disassembled. Despite this, the font works acceptably.