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| How do I get the resitance of the DCA ranges? |
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| ballsystemlord:
Hello, Often higher end meters specify the burden voltage of the amps range. For example, 100mV/mA would give us a 100ohm resistor. But some meters only list the voltage drop as a < X.XXX number. Like the attached image. How do I get/approximate the resistance of the meter's amperage ranges? Thanks! |
| bdunham7:
Ohms law, R=V/I. So the 10A range states "<0.5V", 0.5/10 = 0.05, that implies the resistance is 0.05 ohms or less. The total resistance includes more than the shunt--there's the internal circuitry and the fuse. That range likely has a 0.01R shunt. |
| ballsystemlord:
I figured ohms law was the way to go, but 11mV burden on 1nA seemed a bit high. |
| bdunham7:
--- Quote from: ballsystemlord on October 26, 2023, 04:25:04 am ---I figured ohms law was the way to go, but 11mV burden on 1nA seemed a bit high. --- End quote --- The burden voltage shown is the maximum at full range. At partial range readings, it should be proportionately less if it is using a regular shunt system. If it is an active system, then the input can't be characterized as a resistance. This meter likely uses a 100R shunt for the low current ranges and a gain amplifier for the very lowest. |
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