Equipment & Procedures > Procedures & Protocols > Circuit Building and Debugging

The following are tips to help first time circuit builders using breadboards build and debug their circuits.

1. If you see smoke or smell something burning, turn off the power to your circuit immediately!
2. Turn off the power before touching your circuit or swapping components.
3. Voltage measurements are relative but usually referenced to common/ground. The multimeter should be in parallel to the component/components whose voltage you are measuring.
4. Review the data sheets of any components being used, making sure to know the pinouts.
5. Integrated Circuits (ICs) such as opamps, need to have an external power source to condition the input signal.
6. If your circuit is not working, try the following debugging tips:
   1. Make sure that you are using the breadboard correctly and you know where the internal connections are. A common first-time mistake is to connect one end of a component to its other end. Consider drawing out the circuit from what you have built on the breadboard.
   2. Confirm that you have a common/ground properly connected in your circuit which is also connected to the common/ground of your power supply and voltage regulator (if being used).
   3. If you are using a voltage regulator, verify that it is inserted and connected correctly, according to the data sheet.
   4. Using a multimeter, verify that the supply voltage to the regulator (if you are using one) and the voltage that the regulator is producing are correct.
   5. Make sure that any ICs/chips that you are using are properly powered and wired according to the data sheet.
   6. Verify that the polarity of polarized components is correct.
   7. Confirm that your resistors have the correct values. Remember, you cannot measure resistance within a circuit, so be sure to remove the resistor before using a multimeter to verify its resistance.
   8. Confirm that all components are making proper contact with the breadboard and that the metal parts of the components and wires are not touching and accidentally creating an unwanted short circuit.