Battery operated clock

[alaric]

I wondered if there might be a hall effect sensor ammeter available. Google found loads of them but digital display. The sensors are cheap and could go around the battery cable. A voltage amplifier on a sensor should be able to drive an analogue gauge. I found a little current sensing module on amazon, which gives 32mV/A:

https://www.amazon.co.uk/Overcurrent-Pr ... 60&sr=8-45

[Craven]

An ammeter works by measuring the tiny voltage drop across the shunt.

billwill,
Sorry to correct a fellow electronics engineer but in an ammeter the shunt is exactly that, the majority of the current is shunted passed the movement so only a small amount goes through it.
Analogue meters are all Current sensing devices, reading a voltage, a series resistor is used to reduce the current through the movement which has a calibrated scale in volts.
An Ammeter has a parallel connected resistor as above, but of course the resistance and power rating is completely different for each type.
FWIW.

[billwill]

An ammeter works by measuring the tiny voltage drop across the shunt.

billwill,
Sorry to correct a fellow electronics engineer but in an ammeter the shunt is exactly that, the majority of the current is shunted passed the movement so only a small amount goes through it.
Analogue meters are all Current sensing devices, reading a voltage, a series resistor is used to reduce the current through the movement which has a calibrated scale in volts.
An Ammeter has a parallel connected resistor as above, but of course the resistance and power rating is completely different for each type.
FWIW.

Yeah, strictly speaking you are right. But I wouldn't be surprised if the coil which deflect the needle, has a varable resistor in series with it for calibration, that portion is then similar to the circuit used for a voltmeter, but the values vary drastically from those used in a 12v voltmeter. Less accurate ammeters as used in vehicles, probably are not calibratable and simply design the shunt resistor to suit the deflection characteristics of the coil meter.

[Craven]

Hi Bill,
Best not get into this but ammeters used are of a Moving Iron type not moving coil.
Cheers.