Uploaded April 2019 | Updated September 2026, 2 weeks ago
In this video, I used the 7805 voltage regulator as an example for troubleshooting 3-pin voltage regulators. The video was supposed to only be 5 minutes, but turned out much longer. The regulator type number denotes the voltage. For example, a 7812 voltage regulator would have a 12 volt DC output. Also, not all regulators have the same pinouts, so this needs to be checked in the data sheets.
A DC voltmeter is used to check both the input and output voltages. If the voltage regulator checks out ok (input and output voltages correct) without a load (output circuit disconnected), then a low-ohms resistor with higher wattage should be connected across the resistor across the output of the regulator to simulate the original circuit load.
External DC power supplies can also be used to subsitute voltage.
Also shown is the drop-out voltage. If the input voltage is not high enough, the regulator will not work correctly. The drop-out voltage information for any particular regulator can be found in the data sheets.
A dead short is also shown, as are some resistive tests.
The input voltage cannot exceed a specified level or else the regulator will be destroyed.
In this video, I used the 7805 voltage regulator as an example for troubleshooting 3-pin voltage regulators. The video was supposed to only be 5 minutes, but turned out much longer. The regulator type number denotes the voltage. For example, a 7812 voltage regulator would have a 12 volt DC output. Also, not all regulators have the same pinouts, so this needs to be checked in the data sheets.
A DC voltmeter is used to check both the input and output voltages. If the voltage regulator checks out ok (input and output voltages correct) without a load (output circuit disconnected), then a low-ohms resistor with higher wattage should be connected across the resistor across the output of the regulator to simulate the original circuit load.
External DC power supplies can also be used to subsitute voltage.
Also shown is the drop-out voltage. If the input voltage is not high enough, the regulator will not work correctly. The drop-out voltage information for any particular regulator can be found in the data sheets.
A dead short is also shown, as are some resistive tests.
The input voltage cannot exceed a specified level or else the regulator will be destroyed.
