On 27 September 2017 at 22:22, ed breya <e...@telight.com> wrote: > I just noticed this discussion recently, so I'm late to the party, but > that never stops me from adding my one-cent's worth. > > David, regardless of the aluminum and other material issues, I think your > initial idea of using a lock-in analyzer is definitely the way to go. I'm > very fond of LIAs, although I seldom need or use them, so my opinion is > somewhat biased. I have five - two Ithaco 391A orange-band, a PAR 5204, an > SR830 and SR850. >
Yes, me too. I have used a number over the years, the nicest of which was the Stanford Research SR830. The EG&G 7260 I own has rather user-hostile interface. There's not even a power switch on the front, and I'm not sure if there's even on on the rear. The following link might interest others who don't know about these instruments http://www.thinksrs.com/downloads/PDFs/ApplicationNotes/AboutLIAs.pdf > > If you use an audio power amplifier for driving the experiment, you can > rig it up so that the LIA can be used to measure the drive current as well > as the resulting voltage drop. Let's say the amplifier is for 8 ohms, so > you put a few ohms in series with the output, then from there into a > precision one-ohm sampling resistor, then into the RUT, forming a voltage > divider. The RUT is expected to be in the micro-ohm region, which is many > thousands of times smaller than the sampling R, so its tiny voltage drop > will be negligible, allowing the sample voltage to be a good representation > of the test current. You could also just treat the whole thing as a voltage > divider and calculate the "exact" results. > I did purchase a Radio Shack 100 W Public address I will set this up later. > > This could be fun and interesting. There are plenty of pieces and > variables involved to experiment with to optimize the measurement, and lots > of other tricks available to enhance it if necessary. > > Ed Yes, with lock-in amplifiers there are an almost infinite set of possibilities of how to do the actual measurement. I don't know if the reference output is a sine wave or square wave on this unit. I have the option of using a Stanford Research DS345 30 MHz function generator to generate a sine wave if needed. There are almost a million things that one can change. Dave _______________________________________________ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.