Perhaps it's possible to detect the voltage drop on the existing [+] line from the battery bank, without the need for an additional shunt.
Some precision, high-current power supplies use a separate pair of "sense" leads between the load and the voltage regulator, so the rated voltage appears at the load, compensating for the slight drop on the main power leads which occurs when high current is drawn. There's certainly not enough voltage drop on the line from Kevin's battery bank to the repeater to measure directly with the RLC-3's 0-5V analog input, but perhaps a well-built linear op-amp circuit could produce a useable 0-5V swing based on the much smaller voltage variation on the main power lead. Thoughts? 73, Paul, AE4KR ----- Original Message ----- From: Jeff DePolo To: [email protected] Sent: Thursday, April 02, 2009 2:20 PM Subject: RE: [Repeater-Builder] Re: Anyone got a Amp-meter Circuit to Repeater Controller for Telementry Readback? The classic textbook method would be to put a current shunt in series with your DC source and measure the voltage drop across it. A current shunt is just a precision low-value resistor capable of handling the thru-current, nothing fancy about it. But, at low voltages (like 12V) and low currents (like a few tens of amps), you end up with small voltages across the shunt in the practical world. The resistance of the shunt has to be kept very low, like in the hundreths or thousandths of an ohm, to minimize power loss through the shunt...
