Multimeter use EX1 How to test Amps with a multimeter

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).

วัดกระแสไฟฟ้า Test Amp current measurement

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

8 Important Testing electronic device on this blog .

Testing electronic device IGBT testing SCR testing Triac Testing Check mosfet and more

Read on this page.

https://www.testmultimeter.com/p/testing-electronic-device-igbt-testing.html

Read more .... all of testing , list of the article here .

30 testing of electronic devices

Multimeter use EX2 how to check voltage with multimeter

Check voltage with multimeter

Multimeter can test voltage , current , resistance. Check voltage with digital multimeter is easy to read the measured value as it a numberic displays. Check voltage with analog multimeter will explain too.

Step to check voltage with multimeter.

The most important point to check voltage with multimeter is the appropriate range selection and the right test leads connection.

1. Estimate the target voltage amount , seek information from device label , manual ,calculation. Unknow voltage must set voltage range to the highest range. For example test 6VDC battery use 10VDC range (analog multimeter ) , 220VAC socket use 250VAC range. Low cost digital multimeter must choose range by manual but advanced digital multimeter can provide auto range.

2. Plug the red test lead to V terminal and the black test lead to COM terminal , see photo. While testing do not touch the tip of test leads , always hold at insulated area of test leads.

3. Turn range switch to the appropriate range , DCV range for testing DC voltage and ACV range for testing AC voltage. Some model of digital multimeter has auto range but some model of digital multimeter has not , you have to select the suitable range by manual , for example 6VDC battery choose 20DCV range to check.

6VDC battery select DCV range to check , the multimeter has auto range.

DC voltage has polarity so it must connect red test lead to positive terminal ( V+) and the black test lead to negative terminal ( V-).

Test multimeter Test Volt with multimeter

6VDC battery select 20 DCV range to check , the multimeter has not auto range so user must select the appropriate range for target voltage.

วัดแรงดันไฟ check Voltage with multimeter

The target voltage across resistor is DC voltage so select DC range to check.

Select 10DCV range to check 6VDC battery and read value from 10 DCV scale.

In this case multimeter point at 5.9VDC.

4. Disconnect the lead tests before changing the voltage range.

5. Read the measured value from display.

วัดแรงดันไฟ AC Test Volt with multimeter

Select AC voltage range to check 220VAC socket. AC voltage has not polarity so it can switch test leads.

Select 250ACV range to check 220VAC socket. AC voltage has not polarity so it can switch test leads. Read measured value from 250ACV scale , this case reading is about 210VAC.

The appropriate AC Voltage range selection

ACV 10 range for testing 0-10V , suitable for 0-10V

ACV 50 range for testing 0-50V , suitable for 10-50V

ACV 250 range for testing 0-250V , suitable for 50-250V

ACV 1000 range for testing 0-1000V , suitable for 250-1000V

The appropriate DC Voltage range selection

DC 0.1 range for testing 0-0.1V , suitable for 0-0.1V

DC 0.5 range for testing 0-0.5V , suitable for 0.1-0.5V

DC 2.5 range for testing 0-2.5V , suitable for 0.5-2.5V

DC 10 range for testing 0-10V , suitable for 2.5-10V

DC 50 range for testing 0-50V , suitable for 10-50V

DC 250 range for testing 0-250V , suitable for 50-250V

DC 1000 range for testing 0-1,000V , suitable for 250-1,000V

Multimeter test EX1 test diode with advance digital multimeter

Test a diode with advanced digital multimeter

Advanced digital multimeter has many useful test function , it is suitable for industrial use , technician level and also fit basic measurement. It provide both auto range and manual range setting , high DC and AC current test function and some model add temperature measurement. Another key feature it passed higher safety standard CAT III , CAT IV level which will print on multimeter to indicate and ensure safety , level of usage. Low cost digital multimeter can set range by manual only so it is suitable for student , DIY circuit , basic repairing. Here it will use advance digital multimeter to test diode. Is it easy to use ? , measurement below will give an answer.

Advance digital multimeter for industrial and complex measurement , technical level

Low cost digital multimeter for basic measurement.

CAT IV Measurement Category level is suitable for industrial measurement.

Step to test diode with advance digital multimeter.

1. Insert the red test lead to V Hz ll terminal and the black test lead to COM terminal.

2. Turn the range switch to Diode Test. The screen will display diode symbol as above photo No.1

3. Forward bias to diode , connect the red test lead to Anode terminal and black test lead to Kathode terminal. Good diode will display 0.3-0.8V. Shorted diode display 000 , open diode display OL.

Kathode terminal has white stripe indication.

วัดไดโอด Test multimeter Test diode with multimeter

Forward bias to diode , good diode will display 0.3-0.8V forward voltage drop

4. Reverse bias to diode , connect the red test lead to Kathode terminal and the black test lead to Anode terminal. Good diode will display OL. Shorted diode display 000 ( or very small amount such as 002)

Reverse bias to diode , good diode will display OL.

4. Shorted Diode will display 000 ( or very small amount such as 002) for forward biasing and reverse biasing. Switch the test leads also still get the same display as 000.

Shorted diode will display 000 ( or very small amount such as 002)

4. Open Diode will display OL for forward biasing and reverse biasing. Switch the test leads also get the same display as OL.

Open diode will display OL , switch the test leads still get the same OL display.

Multimeter test EX2 test a diode with Digital multimeter DT-830B cheap multimeter

Test a diode with Digital multimeter DT-830B

The digital multimeter model DT-830B has a diode check range , It is a cheap multimeter so some testing display may different from an advance and higher price multimeter. Its diode check range will supply 2.8V and 1mA test current so you can use it to check LED and Zener diode too , as it supply very small test current to save battery life time so LED does not light , however , it still indicate good or bad condition by display voltage drop.

Step to test a diode with cheap multimeter.

1. Insert the red test lead to VΩmA terminal and the black test lead to COM terminal.

2. Turn the range switch to Diode check and it will display number 1 as above photo.

3. Forward bias to diode by connecting lead test with diode as below. Note the testing is done when diode is not on circuit and there is no voltage present on diode. Always remove power source from diode before testing.

Forward bias to diode , good diode will display some forward voltage drop and the unit is mV so this testing value is 536mV ( 0.536V)

4. Reverse bias to diode connect test lead with diode as photo below. The good diode will display number " 1 ". , it mean ∞ Ohm ( not connected or not shorted )

Reverse bias to diode , good diode will display number "1" mean ∞ Ohm ( not connected or not shorted )

5. Bad diode (shorted ) always display 000 for forward biasing and reverse biasing.

Shorted diode always display 000 , switch the test lead it still get the same display 000

6. Bad diode ( open ) always display number "1" for forward biasing and reverse biasing. This Time is mean ∞ Ohm as diode open so there is not forward voltage drop display and no current flow when forwarding biasing.

Open diode always display "1" , switch the test lead it still get the same display "1"

Multimeter test EX3 test mosfet with digital and analog multimeter

Test mosfet with digital and analog multimeter

A power component has high current , high wattage may be broken as shorted condition and open condition. Before other process testing , you may firstly check shorted condition and open condition. Testing mosfet has some detail and all steps of testing must be good so it is a good mosfet. If any of only testing step is fail , the mosfet is already broken.

N Channel MOSFET Symbol

P Channel MOSFET Symbol

Step to test mosfet with a digital multimeter

1. Discharge mosfet . short 3 terminals D-G-S together by using resistor legs or other metal wire. then remove resistor leg. After shorting 3 terminals , do not touch any mosfet terminal again. If you touch it by error , it must re-discharge. The area which can touch and hold is the black case of mosfet.

2. Test G and D terminal , read the measured value. Switch the test lead and read the measured value again. A good mosfet , meter will display "OL" 2 time.

Discharge mosfet . short 3 terminals D-G-S together , G D S is terminal arrangment.

Test G and D terminal. The first testing.

Test G and D terminal. The second testing ( switch the test lead)

3. Test G and S terminal , read the measured value. Switch the test lead and read the measured value again. A good mosfet , meter will display " OL" 2 time.

Test G and S terminal. The first testing.

Test multimeter Test mosfet with multimeter

Test G and D terminal. The second testing ( switch test lead)

4. Test D and S terminal. Use Ohm range to test D and S terminal and read the measured value. then switch the test lead and test again. A good mosfet will display " OL " 1 time and display high resistance 1 time. Some model of mosfet has internal diode connect across D and S terminal , this case you can use diode range to test it. Bad mosfet will display differnt ways that is , shored will display very low resistance 0 Ohm 2 time , open mosfet will display " OL" 2 time.

Test D and S terminal. Use Ohm range will display high resistance 1 time.

Test D and S terminal. Use Ohm range will display " OL " 1 time.

Please be careful after discharge mosfet ,don't touch any terminal. Always hold mosfet at insultated case.

Step to test mosfet with a digital multimeter

1. Discharge mosfet . short 3 terminals D-G-S together by using resistor legs or other metal wire. then remove resistor leg. After short 3 terminals , do not touch any mosfet terminal again. If you touch it by error , it must re-discharge. The area which can touch and hold is black case of mosfet.

2. Test G and D terminal. Set range to Rx10K and do zero ohm adjustment. Connect test lead with D and G terminal then read the measured value. Switch the test lead and read the measured value again.

Good mosfet , the pointer will point at ∞ 2 time.

3. Test G and S terminal. Set range to Rx10K and do zero ohm adjustment. Connect test lead with G and S terminal then read the measured value. Switch the test lead and read the measured value again.

Good mosfet ,the pointer will point at ∞ 2 time.

Test G and D terminal. Good mosfet , the pointer will point at ∞ 2 time.

Test G and S terminal. Good mosfet , the pointer will point at ∞ 2 time.

4. Test D and S terminal. Set range to Rx10 ( or Rx100 ) and do zero ohm adjustment. connect test lead with D and S terminal then read the measured value. Switch the test lead and read the measured value again.

Good mosfet ,the pointer will point at low resistance 1 time.

Good mosfet ,the pointer will point at ∞ (or high resistance ) 1 time.

( some model it will point at high resistance instead of ∞ )