Re: Analog Opto Isolator?

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "vrsculptor" <vrsculptor@...>
wrote:

>
> Hi,
> I'm messing with a very basic RC EDM (Jon Eleson's) and want to
> measure the voltage drop across a resistor using a micro (coridium
> Armite) with an analog 5 volt input to sense the spark gap. The EDM
> voltage is adjustable so I can't use a fixed resistor network to keep
> the sense voltage within 5 volts.

I'm not sure I agree with your premise.

If your spark is between 1 volt and 100 volts, with 100 volts yielding
5 volts to the sense line of your micro, your micro would easily be
able to sense the voltage within one volt, no ?

I think the real question is that of isolation. And, again, I am not
sure I agree with your premise.

the DC power supply to the micro needs to be rock solid, the input is
supposed to fluctuate.

Just tying the grounds together should be good enough.

If you want more, consider using an op-amp after an opto. the op-amp
would offer a means of offering you the ability to amplify your signal.

Also, with a slight bit of circuitry, you can use one pot to both
adjust the spark voltage and also re-range the sensor.

Dave