CHAPTER 11 ■ POWER ON!Measuring In-Circuit Voltage
Testing voltages throughout a circuit is the most common test you’ll perform. This tells you whether each
part is receiving the desired range of “pressure.” Too little voltage and the part won’t operate; too much
voltage and the part will break.
- Set up your multimeter as you would to measure battery voltage (see Figure 11-3).
Use a hook or alligator clip adapter on the black (COM) test probe. However, the
red test probe should be a bare metal tip since you’re going to move it around a lot. - Turn on your LED circuit. The measurements are going to be made with the
power on. - With the black alligator clip still attached, connect the multimeter’s black test
probe hook to the negative terminal of the 9 V battery (see Figure 11-4). The
black test probe will stay there as you touch the red test probe tip to various other
locations on the circuit.
Figure 11-3. Multimeter setup for measuring voltage at various locations in a circuit
Figure 11-4. Black probe hooked onto negative battery terminal. Red probe can be moved freely