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Re: leader strike photo idea - Tesla coil spark current meter



Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Peter,

Cool idea!!

I have burnt out LEDs doing this in the past but they "still light"!! In fact, a "burnt out" LED lights fine under high voltage. So it may seem like the LEDs work but if you go to power them up normally they might look dead. However, if the LED still "works" who cares ;-))

I did look at the LM3914 circuit today but the LM3914 starts to pull off at 20kHz and is totally gone at 50kHz. If one wants to do a linear bar graph, it would probably have to be made out of discrete comparators and such. I might still look into that since it would be so cool ;-))

Cheers,

        Terry


At 08:30 AM 9/25/2006, you wrote:
I have made a current meter covering a theoretical 6 orders of magnitude using a simple resistor/LED chain.
Circuit diagram here
http://tesladownunder.com/HVpolarityVU1Schematic.jpg
Pic here in action
http://tesladownunder.com/HVpolarityVU1.jpg
Also would you believe that a red LED could take such abuse and still run with a 2 inch spark directly onto it (without reverse protection). Well for a few minutes at least on my ignition coil setup.
http://tesladownunder.com/HVpolarityLEDSingle.jpg

Peter


Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>
Hi Jim,
I am working on an LM3914 bar graph "scope" to do this. The only thing I don't know is how fast the LM3914 will operate. It might have to go to near 1MHz!!
Cheers,
        Terry