Analog multimeter + diode bridge - dual polarity current

[atferrari]

I am about to start testing some current sources. Output varies between -1000 mA and +1000 mA. Voltages involved: -5V / +5V.

I will use an analog multimeter. To make it simpler and avoid damages (wrong polarity), I considered using a diode bridge.

I need this not to be fast nor extremely precise, just to allow appreciating if for equivalent control voltages (measured with a DMM) the absolute value of the currents is in the ballpark.

Not sure if the use of diodes requires kind of spectial additional precautions.

Gracias for any suggestions.

 

[Tony Stewart]

I am about to start testing some current sources. Output varies between -1000 mA and +1000 mA. Voltages involved: -5V / +5V.

I will use an analog multimeter. To make it simpler and avoid damages (wrong polarity), I considered using a diode bridge.

I need this not to be fast nor extremely precise, just to allow appreciating if for equivalent control voltages (measured with a DMM) the absolute value of the currents is in the ballpark.

Not sure if the use of diodes requires kind of spectial additional precautions.

Gracias for any suggestions.

If these are intended to be CC LED drivers then use any DMM in 1a or 10A scale with rated power diodes in series to simulate the LEDs. Or consider a high power halogen bulb with a cold ESR of 5 to 100 Ohms as a load to match supply.

But perhaps most elegant is to use a 10W transistor and 50 mV shunt resistor and sweep Vbe around 0.65 +\-0.1 and scope XY with V vs I using a sig.gen at slow rate to bias Transistor.

You understand Ohm's Law right?

 

[atferrari]

If these are intended to be CC LED drivers then use any DMM in 1a or 10A scale with rated power diodes in series to simulate the LEDs. Or consider a high power halogen bulb with a cold ESR of 5 to 100 Ohms as a load to match supply.

But perhaps most elegant is to use a 10W transistor and 50 mV shunt resistor and sweep Vbe around 0.65 +\-0.1 and scope XY with V vs I using a sig.gen at slow rate to bias Transistor.

You understand Ohm's Law right?

No LED drivers specifically, just for experimentation.

The MM has a 10A range. I am not going fancy because I intende to test output against the existing manual controls. Two of them are for floating loads and one for a load referred to ground (0 V).

 

[KeepItSimpleStupid]

You might try a current sensor such as this one: https://www.pololu.com/product/1185. The voltage drop would be lower than a shunt ammeter. I've designed zero resistance ammeters (Feedback ammeters) to work at 100 mA,they generally don't work in that range. The beauty of the current sensor is that it inherently has isolation.

You have to decide what the maximum voltage drop you can tolerate is.

Zero center analog meters exist and you can turn a shunt into a voltmeter, but your somewhere in the middle. For my +-100 mA meter, my operating voltage would include 0V and typically was -1.5 to 1 V.