ammeter and voltmeter needed

williamwright · 2020-09-05T16:52:12+00:00

I've been ages searching and I can't find what I want, though it sounds so simple. It's a digital ammeter/voltmeter combination. The max voltage to be read is 16VDC; the max amps to be read is 20A. The supply voltage is nominally 12VDC. It would be perfectly OK for the voltmeter and ammeter to be separate units.I found a product priced at around £20, which seems a bit cheap to me, but delivery is 20th - 29th Oct, and it only reads up to 15A 15A would be OK at a pinch, but I can't wait until 20th Oct.I'm assuming the ammeter is 15-0-15 as well, although it doesn't say so. I do need centre zero.I do have a 30-0-30 analogue meter but 2A scarcely moves the needle, and I will need to see a confirmation of that sort of low current use/charge.I don't want a hall effect device; I want something with a shunt.I've looked all over. I must be looking in the wrong places. Can anyone who is conversant with such things and knows the suppliers help?Bill

Sep 05, 2020 Last reply: 5 years ago 22 Replies

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Dave Plowman (News 5 years ago

Maplin did just such a kit many years ago. Measuring the voltage drop across the main ground - battery to chassis. It had several modes - but one was driving a tri-colour LED. Red for discharge, green for charge, amber for the load just balanced.

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Paul 5 years ago

You can make meter movements that are critically damped or overdamped, for instrumentation.

All that making an underdamped meter does, is avoid paying license fees to some patent holder.

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"Pointer and coil tend to oscillate before settling. Damping force is provided by eddy current in the aluminium coil former."

This means there is a design method to modify the dynamic behavior of the meter needle.

Paul

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Paul 5 years ago

You can calibrate using a clamp-on DC ammeter.

Those do +/- and also handle very large currents.

Paul

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