I was looking for some parts a couple of weeks ago and came across an old TV flyback transfomer, so I thought I would build a project with it.
Of course, using a flyback transformer for high voltage generation is probably one of the easiest project for people just waded into the electronics DIY world. Not only is the involved circuitry very simple, but the generated high voltage is considered relatively safe as well. Plus, looking at the bright blue spark is quite a unique but satisfying experience. So, here I will show you my version of the circuit (well it’s not that much different than the many designs found on the internet).
In this circuit, I used a pair complementary power transistors (TIP31C, TIP32C) to form a totem pole driver. For the output stage, you can use a TIP41C power transistor. In my implementation (see picture below), I used two parallel TIP31C’s since I have many of these lying around.
When using the above mentioned transistors, the supply voltage used can be from 9V to 18V. It is always a good idea to start with a lower voltage to minimize the possibility of damaging the power transistors or the flyback transformer in case there was a wiring issue.
Here is a picture of the spark generated with the above circuit when driven by an 20Khz 50% duty cycle square wave from a 555 pulse source.
