I'm after something that will drive 2 moving iron meters randomly, so they just kinda sit there and jiggle around (a friend has an old instrument panel with them in and wants to get it wired up to sit there in the corner and look cool). I was thinking of maybe a sine wave generator, but thats not going to be a very random movement, and the only kit I found for a sine wave generator ran at 6HZ min. which is too fast. Can anyone point me in the right direction?
are these AC meters? If so, all you gotta do is make a circuit that will take an AC power source and reverse the polarity every second, or however fast you want the meter to move.
You can get a simple flickering by mixing the outputs of 2 or more oscillators running at different frequencies, examples here but for true randomness a noise generator would be better. Moving iron meters usually need a few amps to get full-scale, so you'll probably need a booster transistor to amplify the signal.
A few amps?? Wow I didn't realise they would need that sort of clout! Can I tell by their internal resistance what sort of current I'll need? The meters are pretty chunky (and old). One is volts, 0-60, the other amps, 0-50. Basicially I just want the needles to jigle about and look cool. I have an old 9v 1A wall wart style PSU that I was hoping to power the meters and a few LEDs...
I'm thinking of the big brass moving iron meters I've seen in some of the junk at work, but yours don't sound too promising. Moving iron meters have a hollow electromagnet inside, that pulls an iron piece in fastened to the needle shaft. They'll work on either AC or DC, but they aren't made as sensitive as DC-only moving coil meters. Check the internal resistance of the ammeter, if its fairly high it means it's supposed to work off a current shunt, so it could be adaptable to lower currents than 60A. If the voltmeter has a built-in resistor to alter the scale you might be again be able to mod it. The 60V meter should jig about nicely on a 50W amp speaker terminals.
