Test Amps with a multimeter
A multimeter has current test range , uA mA A , the maximum current that the multimeter can test depends on multimeter model 10A or 20A . Analog multimeter can test DC current only but Digital multimeter can test DC current and AC current , some important information is printed on multimeter. Be careful when testing DC current because it has a polarity and current flow direction , user must properly connect the test leads and select the appropriate range.
Digital multimeter can test DC and AC current range uA mA A
Digital multimeter can test DC and AC current range uA mA A
Analog multimeter can test only DC current , DCmA range
Step to test Current.
Simple circuit will be used for current test demonstration.
1. Estimate current amount and seek information from label , manual and calculation. For example from simple circuit below , from equation V= IR , I = V/R so 9VDC / 1K ohm = 0.009A or 9mA
2. Select the properly range for target measured current. For sample circuit below , the suitable range is mA range ( for digital multimeter) and 250mA range for analog multimeter. Turn range switch to that range.
3. Plug the red test lead to + terminal and the black test lead to - Com terminal.
Simple circuit to demonstrate current testing.
4. Always turn off circuit before connecting with the multimeter test lead.
5. Connect the test leads with circuit as photo. For current testing , it must connect multimeter series connection with circuit.
6. Double check if the test leads properly connect and set the right current range has chosen. Be careful DC current has a polarity and current flow direction , wrong connection will cause multimeter damage.
7. After double checking polarity and the right range , then turn on the circuit.
Multimeter series connection with simple circuit to demonstrate current testing.
8. Read the current on display. It can change range to higher or lower range if scale is not easy to read. Before changing any range , always disconnect the test lead and turn off the circuit first.
Plug the red test lead to A terminal as mA socket is not suitable for 9mA (over range).
Select 20m DCA for testing 9mA target measured current.
Select 25DCmA for testing 9mA target measured current. Reading from scale 250 Scale , Full scale 25mA will point at 250. This case it point at 90 so the reading current is 9mA
The appropriate DC range selection for analog multimeter.
DC 50uA for testing 0 - 50uA , suitable for 0-50uA
DC 2.5mA for testing 0 - 2.5mA , suitable for 50uA-2.5mA
DC 25mA for testing 0 - 25mA , suitable for 2.5mA-25mA
DC 250mA for testing 0 - 250mA , suitable for 25mA-250mA
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