[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: LED Charge Indicator

Original poster: "Peter Terren" <pterren@xxxxxxxxxxxx>

Neons are easiest and their rated current is less than 1mA (typ 600uA). I am using a system on my 10kV 8kJ cap with a resistor chain of 20Meg (20 x 1meg x 1/2W) with a neon in series (ie switches on at a low voltage of 70V). This is in series with a relaxation oscillator with a ?.001uf cap 630V which is in parallel with 4 series neons. Experiment with the cap and the desired flash rate.
So visually you get a neon that is always on with any significant charge, plus a flashing neon set that flashes faster with increasing charge.
I believe these are vital for high energy caps but not so much for Tesla stuff, depending on your setup as the cap is normally discharged through the power transformer when power is off unless you have a DC setup.
I am sure you could do the same thing with a LED as the high output LEDs (>5000mcd) will be very visible at 1mA average current. You could use a flashing LED with appropriate parallel resistor or zener to prevent over volting it. Also it will be polarised so need to account for this as voltage reversals may occur depending on your application.
The other advantage of a light indicator is that it discharges the cap to prevent dangerous voltages from hanging around and also reaccumulating. My defib caps recharge by a few hundred volts if you leave them open.

Peter
http://tesladownunder.com/

Original poster: "Dan" <DUllfig@xxxxxxxxxxxxx>

some industrial equipment that have built in capacitors, have a red LED on the front panel to indicate if the capacitor is holding a charge. Can this be done with the capacitors in a TC, or are the voltages just too high?