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I build an inverter to power some panels of EL paint (If you don't know what EL paint is check out this link). It puts out some very high voltage and I thought I'd check to see what amperage it is capable of delivering since the voltages it is operating at are rather dangerous (I measured 329v with my meter). Anyways, I tested the output amperage in several different ways. First I checked the amps on the high side while it was powering the EL panel and got ~874uA, pretty small. What really surprised me was that when there was no load present (direct short) my meter only measured 10.5mA, still pretty small. I would have thought that shorting the ends of the transformer through the meter would have caused bad things to happen, specifically white smoke and a melted transformer, but I experienced nothing of the sort.

I tested it with several different MOSFETs and also tried a small transistor (2N3904). The transistor actually caused it to supply less amperage so my thought is that it has something to do with the amount of current the MOSFETs and transistors are allowing to flow through them. My question is, why am I seeing such a small amount of amperage on the output of the transformer? Also, is this design safe since 10mA isn't fatal and the human body would provide some resistance lowing that number a bit more?

Datasheets: Transformer MOSFET 555 Timer

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  • \$\begingroup\$ Why have you bothered with a 5V buck converter? The 555 runs happily from 12V and you stand a better chance of turning on the MOSFET properly. \$\endgroup\$ – Finbarr Aug 10 at 20:38
  • \$\begingroup\$ 2mA can be fatal if it hits at the "right" well, wrong, time in the heart beat cycle... \$\endgroup\$ – Solar Mike Aug 10 at 20:40
  • \$\begingroup\$ In the future I'm planning to use this circuit with an Arduino. The 5v side of things in this circuit will be powered off the supply voltage of the Arduino. \$\endgroup\$ – Jake L. Aug 10 at 20:42
  • \$\begingroup\$ That design is "not entirely unsafe" if the switching frequency is at least 1kHz. Muscles cannot follow such a high frequency. Still, there are dielectric effects which makes it unhealthy to touch the high voltage side. \$\endgroup\$ – Janka Aug 10 at 20:49
  • \$\begingroup\$ It is doubtful that your current meter can show you anything useful at the (aproximately) 1.5kHz the 555 is oscillating at. \$\endgroup\$ – JRE Aug 10 at 21:23

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