Recent content by Zapitgood

Would be nice of you to share the answer for us rabid researchers

Totally out of my field but I think at least with the double probe it is biased between the 2 electrodes and current across or through the sensor is measured. The bias voltage is varied to extract specific current v.s. voltage anomalies. Can be thought of as a source/measure device. The plasma...

I know this is an old post but I think the LED as the bias is for temperature compensation. I have seen this in transistor current source applications, never used it myself but the led junction has the opposite TC as the Vbe junction. Well almost. re: From WIKI...

I think I figured it out, forgot that SPICE inserts a resistor in parallel with current source and in series with voltage source to prevent simulation problems. Of course I was working with "ideal" components as that's all I stock in my lab... I pay extra for those you know. Thanks for the...

Trying to simulate leakage current, say from a reverse bias diode or even a dirty PCB. Getting funny results using the current source across the load. Anyone have any ideas. Basic voltage divider fed by CV source and a 1uA forward biased CC source across the VD tap. By the way, I'm fairly new...

Never seen that approach specifically, guess it comes down to the accuracy/stability of the correction components.. Being fairly lazy, I would put everything in a crystal oven (mostly because I have a few lying around) and run above ambient. That might stabilize the bias current ? But you will...

I have used these picoamp input amps before, have to be very careful about layout, use guarding whenever possible. I had to lift the pins and connect the sensor "dead bug" style to reduce leakage. Keithley instruments has a really great handbook called "Low level measurements handbook" that is...

Ok, a very crude experiment this morning yielded these results. Not knowing the actual parameters I used a 50uS 5V pulse (about 10nS rise/fall) in series with a 270pF cap and into the Fluke on peak capture, millivolt range. Readings were about 220uV avg, pretty poor resolution. So some...

I agree, that would be the best approach. I think the input Z is much higher, there are other models with a power on feature that removes any shunt R. That being said even a Gohm would be pretty quick, but using the 250uS peak hold function should capture the event nicely even with 10M/2.44mS decay.

For a "backyard" operation you might get away with just a voltmeter with a high resistance in series. The charge will start to go down pretty quick but with reed switch in series with the meter and a quick eye (or a peak hold reading voltmeter, readily available for cheap) Depending on your...

Here is a link to a Kapton wire mfg.. http://www.allectra.com/pdf/Kaptonwires.pdf AC or DC ? In short, take the Kapton V/mil x wall thickness (For DC only)

Here is a not so huge table I have compiled. Sorry it's not in text format, you will have to type it into your database.

Flukes are great but probably not in that price range... Extech makes some pretty decent DMM's for cheap.. Lot's of other functions for the same price as the Fluke (Temp, transistor checker, data logging)

There are tons of circuits on the web, search for current source, not supply. Here are a few schematics.. You can beef up the current with a transistor. Also check out Bob Pease article on current sources. http://www.edn.com/contents/images/6309110f1.pdf...

Here is a link to BELA http://femm.foster-miller.net/wiki/HomePage