On 2006-02-01, John Fields wrote:

Hi all,
I need to switch high voltage (1kV at 2kHz AC), low current to
sequence some electro luminescent wires. I'm working on the trigger
sequencer and I have the high voltage/ high frequency PSU but I'm not
sure what kind of device/technique to use for the actual switching
between 5 channels. Any suggestions greatfully received.
Thanks in advance,
UK Pete

.. Ooops Make that 200V AC @ 2kHz...

MOC3021 (upto 100mA) If you're in the UK that part (or similar) should be readily
available, it's an optocoupler used to drive triacs but also seems suitable to
switching 200VAC at low currents.

I don't think so.

His 200V drive is almost for sure going to be coming from an
inverter with a rectangular output waveform.

and that'll be a problem ?
could it be solved using some sort of low-pass filter?

Take a look at pages 4 and 5 of:

I'm not sure what to look for
I see a curve for on voltage that puts it at around 1.5 for 100mA
150mW is well within the reasonable range.

I see figure 5, and the circuit top of page 5

200vX200Khz 80000V/s = 0.08V/us if a triangle wave
more if a sine wave, yet more if a square wave.
but with a square wave would switching on a little late be a problem?

Is a solid state relay likely to perform better?

http://www.fairchildsemi.com/ds/MO%2FMOC3021-M.pdf

thanks for searching that out, I'd misplaced my copy and was looking at a
summary in a paper catalogue.


I see the bit that says "This optocoupler should not be used to drive a load
directly, it is intended to be a trigger device only."

But these electroluminescent wires only draw a few milliamps it's not like
trying to switch a lightbulb where the cold current can be a few amps.

What am I missing?


--

Bye.
Jasen