To make sure a diode is connected correctly, follow these key steps:
1. Identify Diode Polarity
- Diodes have two terminals: anode (positive) and cathode (negative).
- The cathode is usually marked with a stripe or band on the diode body
2. Match Diode Orientation with Circuit
- Check the circuit schematic or PCB layout to confirm which side the anode and cathode should connect to.
- The diode should be oriented so current flows from anode to cathode (forward biased) in the intended direction of the circuit
3. Use a Multimeter to Test Orientation
- Set a digital multimeter to Diode Test mode.
- Connect the red (positive) lead to the diode's anode and the black (negative) lead to the cathode.
- A correctly connected, good silicon diode shows a forward voltage drop between about 0.5 V and 0.8 V.
- Reverse the leads; the multimeter should show OL (open loop), indicating no conduction in reverse bias.
- If the readings are reversed or the diode conducts both ways, it is connected incorrectly or faulty
4. Visual and Physical Inspection
- Confirm the diode’s cathode marking aligns with the cathode side in the circuit.
- Ensure the diode leads are securely and properly soldered or connected to the correct pads
5. Functional Testing in Circuit (Optional)
- If safe, power the circuit and verify the diode performs as expected (conducts forward current, blocks reverse current)
By combining polarity identification, circuit reference, and multimeter diode testing, you can reliably ensure a diode is connected correctly in your circuit
