Simple capacitance meter, preferably analog?

Nice, but unfortunately fixed at 1MHz.

They do. I have their megacycle meter but unfortunately this time I need

I had looked at that. AFAICT the AADE meter is charge-discharge and with too much amplitude.

Shuod be analog anyhow. They have an HP capacitance meter but its digital display jumps around way too much.

As I said they don't want to make a science project out of this, just plug in and measure.

Unfortunately no analog display.

I've got an HP3577 but really don't want to ship this rare beast to NY, having seen the sad aftermath of such an attempt (looked like a parachute drop without the parachute). Plus rig-up would be tough, they are not RF experts.

They want something to just plug in. Like the meter John suggested except we can't use 1MHz.

I have one working here at 7kHz, homebrew. It uses a resonant method and can reliably and very repeatably show a change from 500pF to 501pF and back. But it's a homebrew PC-based system with graphing and all and they need a simple box.

On the (big) rig-up I have here running at 7kHz I once had a ceramic cap from my parts bin on it to test. A draft developed in the hallway and the door at its end slammed shut. I saw a blip on the graph ... Now I'll be ... went down there again, slammed the door again -> 2nd blip showed up.

One approach would be to use a sine oscillator, all-pass network, comparator, XOR gate phase detector, LP filter, and (optionally) inverse arctan network to linearize.

Cheers

Phil Hobbs

Nice, but all digital and

"Test signal level: 0.5 Vrms Typical" ... way too much.

If I had time, yes. I have a PC setup that works very well for this purpose and even writes a graph. But only one, I need it here simultaneously and no time to build #2.

Well ... I just found that the Boonton 72C operates at 100kHz. Still a stretch but we could take a chance. That one is rare and that is unfortunately reflecting in EBay prices.

I have a 72C that I can lend you (I owe you one for the PMT gig, for one thing).

Cheers

Phil Hobbs

Whoops, I only have an A and two BDs, both 1 MHz. Sorry!

Cheers

Phil Hobbs

I don't know any model numbers (or even if such things exist) but a capacitance bridge that can accept input form a sig. gen.

George H.

There's a 71K on eBay that runs at 1 kHz:

Cheers

Phil Hobbs

Thanks. I sent a used equipment link to the guys for a 72C. It should be fine at 100kHz.

The PMT goes to fab now. Revenue-wise I am deep in the hole but it sure was fun. Engineering is supposed to be fun, else we could all be investment bankers, dentists or lawyer.

That would be perfect but 1V output does not work for us.

I just had to take my lumps for an optical gig that turned out to be too hard. Lots of non-billable hours trying to fish that one out. :(

Cheers

Phil Hobbs

There are some decent Chinese c-bridges, but they are digital, and Joerg wants analog.

This high-voltage pulser that I'm doing will probably be a big money loser. But's it's amusing, which is worth something.

Yeah, we all run into that from time to time. But there is always a learning effect or some other benefit. I was able to explain to a youngster how a PMT works without the opportunity to consult a search engine. Last fall I couldn't have done that.