USB 5V Audio Amplifier for PC Speakers | Homemade Circuit Aug 03, 2019P0 is the output power and is around 3 watts when the load is an 8 Ohm speaker. THD+N indicates the total harmonic distortion which is within 0 to 0% with a frequency range of 20Hz to 20kHz. PSRR gives us the power supply rejection ratio for Vdd at 5V typical, and this is around 60dB. Prototype Image of the 5V USB amplifier: How to Use 5V DC Power Supply from Computer USB Aug 30, 2015If you got fed up of buying new batteries for your circuits and want a reliable power source, then here is way. We use our Laptop or PC to charge you cellphones, similarly we can use power supply from our Computer’s USB for our circuits. Computer’s USB is a good power source for 5v DC regulated supply.