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- To: mail11:;;;;;-at-us4rmc.pko.dec-dot-com-at-us4rmc.pko.dec-dot-com-at-digital-dot-com;;;;;;;; (-at-teslatech)
- Subject: Simple answers
- From: pierson-at-gone.ENET.dec-dot-com
- Date: Tue, 11 Mar 97 10:51:19 EST
Last Night: (which means it will get repeated, sometime, probably thsi weekend) DSC (cable) ran a new (i think) 'lighting' hour: Lightning, Weapon of the Gods which may be of intrest. Some discussion of eg Schumann Resonance and footage of the 'man who paints with a tesla coil'. (He's been in others, i think this is fresh.... ======================================================================= >2. A more technical question. I don't understand the need for the HV primary >voltage. As best I can figure out, what drives the output is primary current, >not voltage - after all, there is no way you will have 15KV across a copper >buss bar Tesla did it routinely. Its all a matter of RF and wavelength. Its not being put across a 'bus bar' (bus bars are used to conduct electricity. 'buss bars' are places to get kissed. 8)>>) Its being put across an _inductor_ which has an _impedance_ which depends on the _frequency_. (True Story: in the early days of uWaves the Lowest Loss 'insulators' were conductive metal standoffs that were 1/4 wave long, and, hence, electrically, an Open Circuit...) >- what you are doing, it seems to me, is creating a big pulse that >then resonates back and forth through a tank circuit made up of the primary >and the capacitor (whilst the spark gap conducts), and the primary only >(higher freq osc) when the spark gap is not conducting. More or less. The objective is actually to get energy into the secondary & keep it there. >So, why can't I just charge up a farad or so of "computer type" electrolytics >to 100VDC and then dump the charge through a 1,000 amp SCR into the primary >directly???? All Those Cost Money. Spark gaps are cheaper. Also 'computer type' eletrolytics have lousy (== LOSSY) high frequency performance. (yes: modern switchers have driven improvements in losses in such caps. They are still highly lossy, at coild driving freqs. Also losses when wiring '1000 A' around are high. Losses detract from performance. By working at a starting level of 5-15 kv currents (and the associated losses) are LOW(er).). That said: >Has anyone tried this?? Yes. Much discussion here on solid state drives of all manner, be they FET, or GTO or .... >This would seem to have several benefits over a spark gap interrupter - lower >loss, Maybe. Conducting around kiloamps is nontrivial. >faster switching, Maybe. A properly managed (rotary, or quenched or ) gap will switch in microseconds. AND has surprisingly low losses. >lower (hence safer) primary voltages, The secondary is still lethal, potentially. The two are together.... >and lower cost primary power supply. 1,000 A SCRs are not cheap. Ditto 1 farad caps. >Comments??? Its been tried. Some success reported. Also, some effects (which gets to the philosophical point: WHY is the coil being built?) seem more readily, or only, obtainable with spark gap coils. regards dwp
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