Links to stuff on this blog

Use the Site Index of Projects page link above for an easier way to find stuff on my blog that you might be looking for!

Sunday, April 3, 2011

A homemade high voltage power supply

The last couple of weeks I have been doing some Schlieren photography with high voltage arcs and sparks. For some of these I used a high frequency AC supply that I picked up out of the garbage. For other experiments I built a high voltage DC power supply from a Dell E551 PC monitor (CRT type) that I saved from the garbage. CRT monitors and televisions have a flyback transformer that steps up a voltage and it usually does it at a high frequency. Click on the above Wikipedia link if you want to know more about them.
Before I go any farther let me say that CRT's, monitors and televisions have HIGH VOLTAGES in them and can retain the high voltage long after they are turned off and unplugged. DON'T TAKE ONE APART unless you know what you are doing. This blog is just "about the things I am doing" and if not meant to be instructions for you to do the same things. Proceed at your own risk if you decide to do this (or anything else) yourself. Read THIS (scroll down to the orange text) if you are not sure about what I just wrote!
Really cool electric arc from my (hacked together) power supply!
The first thing that I did after taking the transformer out of the monitor is I went on the web and looked for information about these kinds of transformers. There is a lot of information out there so have a look for yourself. I'm not an expert and I don't want to get shocked! It turns out there is a really simple way to drive one of these transformers with just a couple of resistors and a transistor. Read what THIS site has to say to get an idea of what I am talking about. Be sure to read the disclaimer at the bottom of the page linked to above - it applies to my blog as well :-)
Below is a hand drawn picture of the bottom of the flyback transformer pin out that was silk screened onto the PC board in the monitor. Below that is the schematic that I found on the Internet with the connections that I made to the transformer that worked. The transformer has a P/N on it: 19.70060.001 that I looked for on the web but couldn't find any information about. Nevertheless I got it to work with a little trial and error.
Single Transistor Flyback Transformer Power Supply.
The transistor that I used I also got from the Dell monitor. It was the transistor that was driving the transformer so I figured it would work here as well. The P/N on the transistor is C5520P and an Internet search didn't reveal much about it other than it's a NPN transistor. The resistors I had laying around and from the site that I got the schematic they recommended a power resistor for the base to ground position (50 ohms). I mounted the transistor to a heatsink, connected everything in a hack sort of a way (because I didn't really think this was going to work) and powered it up with 20 volts DC.
Hacked Together High Voltage Power Supply
It doesn't look like much but it worked pretty good. When I powered it up I could hear it running with a high pitched whistle sound that came not only from the transformer but also the AM radio in the garage. Otto Jr. had fun drawing 1" or so arcs in the dark.
This was a neat little thing to build and I've decided that I'm going to put it in a plastic box or something and redo all the connections. I think that I am also going to build a oscillator to drive the transistor and see if I can get more voltage (bigger arcs) out of it.
Because 'a picture is worth a thousand words, a video must be worth millions' here is a short clip (pun intended) showing it in action - enjoy!

No comments:

Post a Comment