You may not have mentioned what you are using to record the videos and audio. Sounds like aliasing in the audio codec. This can also be heard in analog tape methods when a HF signal beats with the bias oscillator...very interesting sweeping sounds.
Hi ION I was using the built in web cam in my notebook and just sat the notebook in front of the digital scope, the internal mike picked up the sweeping noise many times. You need to remember i am using low volts 25-50 for most of my tests, all i do is pulse the coil for 60-100nS wait a while then pulse again with another 60-100nS pulse. I have seen a number of strange effects happen. In the explosion video at certain phase settings i would get RF/EM bursts these caused my digital scope to crash sometimes and also cause my fet modules to false trigger, it was during these phase settings that i first noticed the explosions noises. now from memory i think it was 187nS gap between the 2 pulses that caused the explosions in the video. There was also a setting that would cause the coils to draw no current and then suddenly 3 amps, it would cycle randomly at a few hertz totally random burst of false triggering in my fet modules. In the explosion video, the top trace was chaotic because of the false triggering of both fet stages, but something was occurring in this false triggering to cause the explosions very occasionally, if i held a magnet near to the coil i could hear constant whitenoise with the occasional explosion, this lead me to build 2 whitenoise drivers, i was working on the principle that the 2 random triggered fet stages were producing 2 Chanel's of white noise and it was this white noise that was causing the conditions to be right for the explosion to occur, it proved fruitfull, now i can use 2 white noise Chanel's without phasing or the nS gap between the pulses to induce the false triggering to cause the explosions. I could do away with the white noise generators if i knew exactly how to produce the explosions, there must be a set of parameters/ timing that causes this, and infact Spheric told us this was the case.
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