Galvanometer???

[TubeGeek]

I have a small collection of vintage meters and recently I unpacked the box they have been in for five years and decided to try and use them.  It is going to be a little project for me to build some kind of wood panel where I can mount these meters and label them so that when I am testing an amp I can monitor multiple voltage and current points simultaneously.

I have one thing called a Galvanometer...from what I read about this meter, I can't see a practical use for amp work, any ideas where/if I could use this thing?


http://www.glacieramps.com/Glacier_Amplification/Vintage_Meters.html

[PRR]

I happen to have just bought a 1963 catalog including Simpson's line. This object is listed as both a microammeter and as a galvanometer, part 1327C or 1329C depending on size.

A basic galvanometer is a compass with some turns of wire around it. It can read very small current, in either direction. A basic galvanometer is uncalibrated. It is excellent for showing small current, also to indicate zero current (exact equality of voltage potential). They were often built big enough for a whole classroom.

What do you do with it?

Connect to gitar pickup, wave a magnet slowly. The galvo needle will waggle. This shows how electromagnetic systems work.

Add a series resistance, it reads voltage. There are few uses for a zero-center voltmeter in gitar amp work; you could bridge it across push-pull cathode resistors to adjust bias-balance.

The meter sold for $18 back in 1963. I bet few survive. There are not many uses, but if someone today needed one, it ought to be worth $20. 

[jjasilli]

http://en.wikipedia.org/wiki/Galvanometer

Yes, they seem to show the existence, direction and amount of a small elec current. The amount may have accuracy issues.

They can show the presence of a tiny current in the human body, for example. I don't know what your 50 -0- 50 scale is:  milli amps, micro amps?  If the former it could measure curren in preamps. If the former, it could be fed current through a voltage divider to get measurements dwon to its level.  Or it could just look cool on a shelf.  Great collection!

EDIT -- URL fix -PRR

[HotBluePlates]

And the real primary use for one, both in the old days and today, is to use the galvanometer in conjunction with a known voltage source and a few other pieces of test equipment to calibrate yet another meter.

When I say "known voltage source" I mean in the sense of an electrochemical cell that has an exact known voltage at a given temperature (usually somewhere in the neighborhood of a volt, but the cell is never exactly "1 volt").

[mackie2]

Unusual Meter--

I once took an old radio, that didn't have a  dial--took an old backwards  reading  noise  meter--Had a  pot coupled to the  tuning cap, Low dc voltage fed pot--Wiper voltage gave a reading number on the noise  meter--had a chart with 4 numbers, my favorite stations--
a lot of work for a dial, huh!

Mackie2

[TubeGeek]

Thanks for the insight on this meter.  It looks like it'll end up being a meter that will pretty much just sit around the shop unless one of you guys would like it?