Some High Voltage Fun

[Sigurthr]

Are those fast-recovery though?

Good point. I have no idea the operational frequency of the eBay_special HV supplies though, so it may not be an issue (or just a minor one). When in doubt grab some 2CL2FMs.

 

[Down with Umbrella]

Good info. That last post I didn't see the updated post before posting mine. These look like good rainy day projects. Ok. Question number two: the optimal power sources. One eBay post says they draw 4-5A(claimed, you know these Chinese seller info is sketchy)
Would a pair of 18650s have better discharge rate vs a 9v?
I might test this.

I wouldn't hook one up to a scope. I try to be careful with that.

 

[Sigurthr]

9V cells are only 500mAH or so, they're mainly for <10mA loads. You might get a few minutes of life out of it depending on actual draw, but most likely it would just load down the voltage terribly. Use LiPos/LiIons.

Yeah, I figured you knew about the no scoping, but it's best to state things like that anyway for future readers.

 

[Atomicrox]

Can't you scope something like this using a very aggressive voltage divider?

 

[Sigurthr]

Not if it is AC output. (I know, I've tried!) For pure DC sure; 1G:1Meg works well as long as you use a HV rated 1G and oil submerge the divider.

The reason you can't do it for AC is the capacitive coupling bypasses the resistors because the impedance of the capacitance is an order of magnitude less than the impedance of the series resistance.

I haven't tested doing a capacitive divider, but I think it might work, albeit very impractical and expensive.

 

[Atomicrox]

Interesting. How about grounding one wire of the hv supply and getting the probe close-ish to the other wire? It should pick up some signal due to capacitive coupling, right?

 

[Sigurthr]

Yep, grounding helps a bit but not much. The problem is if you're interested in amplitudes you need direct connection, not "aerial pickup". If you're just looking for an approximate waveform with no interest to amplitude then just do like with a TC - use an antenna and capacitive pickup with no direct connection.

 

[Atomicrox]

Sounds good, should be enough to check the frequency. I have a similar device (CCFL inverter), might try with it just for curiosity's sake.