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- To: "Tesla List" <tesla-at-pupman-dot-com>
- Subject: 2 simple questions
- From: "William Noble" <William_B_Noble-at-msn-dot-com>
- Date: Sun, 9 Mar 97 18:43:11 UT
1. how do you decide what diameter tubing to use for primaries - I am building a small coil, and I bought a box of 3/8 tubing, but several persons recommended 1/4. I won't be messing with the tubing for a couple of weeks so there is plenty of time to return it and get the smaller (cheaper) stuff. 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 - 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. 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???? Has anyone tried this?? I would imagine having a LC circuit of the tubing for the L, and a suitable AC capacitor, as a tank circuit. Then, the SCR and the capacitor bank would share a common ground with the tank circuit. The SCR would fire, dumping charge, and then the reverse current would shut off the SCR. The pulse would resonate in the tank for a while, then you would fire the SCR again. A crude schematic is represented below: Gate Drive / / L-----|---------------SCR----------|||||||||||||||||||||||||| ------ +++ L C CCCCCCCCCCCC charging circuit L-----|____________________|||||||||||||||||||||||||||_____- - - This would seem to have several benefits over a spark gap interrupter - lower loss, faster switching, lower (hence safer) primary voltages, and lower cost primary power supply. Comments???
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