Measuring "high" voltage

Earlier, there was mension of the series capacitor arcing over. In that context, the 1KV fast rise time spike makes a lot more sense.

i.e., *MONGO* Zener, AKA TransZorb. :-)

Cheers! Rich

We used this as a slow protection clamp on an op-amp output to protect some downstream stuff. Something like an amplifier with +-15V driving some other bits with +-5V supplies and feeble ESD diodes. So we didn't care a lot about accuracy, and we could wait a few us for it to turn on. The primary concern was to make sure the op-amp didn't oscillate, which it would have done had we just used the Zeners.

Had we wanted stiffer clamps we would have prebiased the Zener at a cost of more power and complexity, but this wasn't needed.

BTW, I've just changed my posting address (getting the hang of this Forte Agent thing). To reply directly you'll need to remove the food item from my address.

Steve

On Wed, 2 Aug 2006 13:46:03 +0000 (UTC), snipped-for-privacy@green.rahul.net (Ken Smith) Gave us:

Diodes typically fail shorted. Diodes caused to fail by means of HV can also fail open.

"can" vs "usually"

I think it is really the high current pulse that opens them not th ehigh voltage as such.

On Fri, 4 Aug 2006 01:03:28 +0000 (UTC), snipped-for-privacy@green.rahul.net (Ken Smith) Gave us:

A high voltage breach usually punches through actually removing media. That plasma will always involve maximum available current.

At low voltage, a high current will simply melt the junction.

Not that media can't be lost that way as well, it is just that an HV blow out really does blow out the material.