h0lx Posted April 9, 2007 Posted April 9, 2007 Ok, so I got all the materials'n'stuff for making a tesla coil. But I have a darn problem, namely power. I can get a 25 kV DC PSU, but every page says AC, is it possible to fire up a tesla coil with DC power, if it isn't, then why? I see no problem why it shouldn't, thanks to the spark gap it has alternating magnetic field, which still should induce the enormous voltage at the secondary. I could theoretically get AC but at a maximum of 6 kV.
lja Posted April 10, 2007 Posted April 10, 2007 A tesla coil is a high frequency autotransformer. The spark gap and capacitor used between the primary of the tesla coil and the output of a HV transformer change the frequency of the AC. (It's a tuned LC circuit in combination with the primary). Just using a spark gap isn't going to work, you'll only get DC or at best slowly pulsing DC.
Wyvern Posted April 10, 2007 Posted April 10, 2007 You might want to have a look through this site which has designs for DC tesla coils http://www.richieburnett.co.uk/dcreschg.html
Picric acid DOES taste bitter! Posted May 28, 2008 Posted May 28, 2008 Actually you can run pulsating DC though a transformer just fine, its the same change in magnetic field, but just between one wavetop and zero. 99% of a tesla coil is resonance, so as long as you can tune the DC pulses to match the frequency youll be fine.
Boomer Posted May 30, 2008 Posted May 30, 2008 Tune the DC pulses? At megahertz frequencies?I can picture you sitting there with two bare wire ends, going "... the wave is coming, I see it's close, NOW ... duh too late again ..." You need DC anyway to charge a fat cap bank. The discharge through the spark gap and the primary starts the oscillation. The only ones you tune at the input are the solid state designs where you feed a HF signal in and tune it to the resonance. Modulate the amplitude with a music signal and you've got singing sparks. Edit: You *can* use the HV AC directly for small designs, but this unnecessarily loads the supply. No need to charge the cap 120 (US) time per second in opposite direction.
Picric acid DOES taste bitter! Posted May 31, 2008 Posted May 31, 2008 That is in rotary spark gap designs. If you have variable speed in the spark gap, say 2.000-30.000 rpm, with, say, 10 contact points on the wheel, you get about 5k hertz range to tune the freq. in the supply to match the secondary. Also, the transformer dc was a metaphor to show that pulsating DC cause change i the magnetic field and thus induces a current in another circuit.
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