Moving To Another Voltage Regulator Problem

[KeepItSimpleStupid]

Well, not sure about the 0.2 V rating. hat's not what I have seen by experiance, See http://www.cshunt.com/dc_ammeter_shunts.html

The "shunt" is a 4-terminal resistor. The usual deal is, the inner terminals are the controlled resistance.

Sometimes the troublesome part is that the meter needs to be powered by an independent power supply or with some of the "cheap" meters the shunt has to be in the ground leg.

 

[audioguru]

Well, not sure about the 0.2 V rating. That's not what I have seen by experience.

Most little digital voltmeter ICs like the ICL7106 or ICL7107 have 200mV full scale.

 

[KeepItSimpleStupid]

Yep, Agree. Most shunts have anything but.

Here **broken link removed** 50 mV is more common.

 

[audioguru]

I doubt that a 10A digital meter that costs $2.50 has a 100A shunt.
0.2V/10A= a little piece of wire that is 0.02 ohms. It will dissipate a maximum heating of 2W.

 

[KeepItSimpleStupid]

Depending on your application its not too hard to build a Zero resistance Ammeter with an OP amp/ It's also known as a Feedback Ammeter for low currents. for less than 10 mA it's pretty easy. 100 mA and tiny voltages it's much harder. I've done both. The general equation is Vout = Vb*-I*Rf. Vb is a bias voltage and note the sign change on the output. Ibias, Vos and unity gain stability are the most important OP-amp parameters. I don't have too much experience with single supply versions.

Without any heroic measures, I managed about 40 e-12 amps of offset current.