Introduction: KS-Pi-Power-Supply


Due to a design error (or cheap components?) some Raspberry Pi 3
(Pi) have undervoltage problems with usual 5V power supplies. In extreme cases the supply voltage can drop a dramatic 0.6 volts. Because of this voltage drop the Pi can show the low voltage sign, get very instable – or even crash. The internal Pi voltage should not be less than 4.75 Volts to keep it stable.

Additionally when you use the Raspberry Pi as media center – it would be nice to be able to remotely turn it on or off (Via infrared conrol).

Step 1: Solution

To avoid an instable Pi I assembled a cheap (< 30 Dollars) and powerful (5 ampere up to 6.5 Volt) power supply that can be remotely turned on or off via remote control (a remote control comes with the "Remote Control Module" (I programmed it's signal on my Logitech Harmony remote control)).

Instead of the 5 ampere power supply you could as well use a 3 ampere one – that would be big enough and you could install it in a smaller case. Though make sure that you can change the output voltage with an adjustement screw (ADJ).

The idea is to increase the output voltage from 5 volts to about 5.5 volts.

The USB specification defines that USB components have to work from 4.45 Volts up to 5.5 Volts – so there should be no danger for the USB components.

Step 2: Test With Voltage > 5V

With the ADJ-screw you can set the output voltage of the "Power Supply" from 4.5 to 6.5VDC.

In a first test I did set the output voltage of the power supply to 5.65 Volts and measured at the USB-output of the raspberry pi about 5.32 Volts. This means that my Raspberry Pi has a possible internal voltage drop of 0.33 volts.

(You can start the test with 5.2 Volts and slowly climb until your Raspberry Pi is stable and the low power warning disapears – be careful do not kill it with overvoltage).

In my case at the end I did set the voltage to 5.5 volts – and so far I did not see the low voltage signal again.

Step 3: Components

The components are from Aliexpress.

Step 4: Schematic and WiringStep

Step 5: Movie