williams@kirk.DEC (John Williams 223-3402) (02/11/85)
To the person questioning what kind of amplifiers would be necessary to drive the primary of a tesla coil: 50Khz to 500Khz? Easy. Power transistors can easily handle that. Bias a couple of darlingtons in totem pole, and drive them with an op-amp. Mount the power components on bulk metal to sink the heat. It is well within their frequency response. John Williams
carlc@tektronix.UUCP (Carl Clawson) (02/12/85)
In article <530@decwrl.UUCP> williams@kirk.DEC (John Williams 223-3402) writes: > > > To the person questioning what kind of amplifiers would >be necessary to drive the primary of a tesla coil: > > 50Khz to 500Khz? Easy. Power transistors can easily >handle that. Bias a couple of darlingtons in totem pole, and >drive them with an op-amp. Mount the power components on bulk >metal to sink the heat. It is well within their frequency >response. > John Williams I think most Tesla coil primaries are excited at around 10 Kilovolts. The objective is to generate RF at the secondary in the neighborhood of a megavolt, which is what makes Tesla coils so much fun. The schemes I've seen (years ago, high-voltage semiconductors may be feasible now) all used spark gaps (with neon sign transformers, truly spectacular) or vacuum tubes to excite the primary. For adjustable narrow-band excitation (requested by the original poster) spark gaps are out. (Unless you've got tunable filters that can hack 10 KV!) Look in Popular Electronics around 1964 (June?), they had an issue with a Tesla coil on the cover. They show how to make a big one with a spark gap as well as a weenie one using television parts. I suspect the average RF amplifier won't hack the voltage you need to get a spectacular display from a big coil. Not to say you can't find a high-power amp surplus that will do the job. -- Carl