Brymen EEVblog BM235 User Manual page 23

Diode Tester
RANGE
3.000V
Test Current: 0.3mA typical
Open Circuit Voltage: < 3.2VDC typical
Dave's Note: You can dimly light up most LED's with the Diode range
DC Current
RANGE
600.0A
6000A
60.00mA
600.0mA
6.000A
10.00A 1)
1)
10A continuous, >10A to 20A for 30 seconds max with 5 minutes cool down interval
Dave's Note: It's important to understand Burden Voltage. This is the voltage
drop across the internal current shunt resistor (see values above). When
measuring current this resistor will be in series with your circuit under test and
hence will drop voltage to your circuit based on the current drawn.
For example: On the 600mA range, if your circuit takes 500mA then the voltage
to your circuit drops by 1.9mA * 500 = 0.95V!
So if you have a 3.3V supply, your circuit is only getting 3.3V – 0.95V = 2.35V and
can fail to work properly or at all!
Obviously that's pretty much worst case, at low displayed currents the burden
voltage is pretty negligible, but gets worse the closer to full scale you get.
In this case you can switch to the 6A range and the burden voltage becomes a
negligible 20mV. But you loose a digit of resolution doing this.
All multimeters are the same and have this limitation. Beware
Dave has designed the µCurrent project to overcome this problem. Google it.
Accuracy
1.0% + 3d
0.7% + 3d
Accuracy
0.9% + 2d
Burden Voltage
0.1mV/A (100 ohms)
1.9mV/mA (1.9 ohms)
0.04V/A (40mOhms)
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