No new ideas to post in this blog… To many open projects and no outcome from them… Quite cold outside, my horse is a bit wounded and waiting for small cutting and needle-working
Found old IBM notebook, installed Win98 and inserted SMC wireless network card… No signal found. Maybe my neighbors didn’t use any WIFI (I have 4 start hotel nearby…) …
Ok, ok. Lets talk about welders and TL494. Sometimes it is hard to start arc. Especially if welder is low voltage one. So we must use some sort of the ignitor. In russian sites, I found various schematics- from simple mechanical to complicated. But they are quite powerful and dangerous. I want to build some ignitor by myself.
It will be low power, high frequency and high voltage power supply. Something like ones used in LCD monitors for cold cathode lamps. Original HV supply from LCD is too complex, too sensitive. So I decided to invent bicycle.
Here is my testing boards:
(LCD cold cathode power supply and some selfmade board with TL494 and POWERFULL mosfets)
And after one dead mosfet, change of topology and schematics, first results:
(after some time, 2005.11.20)
Burned holes in paper
I increased frequency to about 200kHz. Replaced MOSFETs to more powerful and faster (CEB603AL). Now device didn’t shock my finger, but burned small hole in the skin (It hurts!). In the image above you can see how it burned holes in simple sheet of paper. There is no need to close circuit- the current goes through parasitic capacitors.
Still there is problems- when powered from 12V, device can work only small time- minute or two. The mosfet is getting hot. I’ll try to put more modern mosfet (95N03?) and increase the frequency…
What about schematics?
Schematics will be soon. Now, the output of the device is unregulated and when I short the output, the power mosfets are getting very hot quickly. Also, the frequency of converter is too low and it strikes human body too much. Output of the device is about 1…2 kV when using transformer from 17″ LCD monitor and the supply is 12V.
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