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Saturday, June 30, 2012

Reducing power consumption of a raspberry Pi - BitWizard WIKI

Reducing power consumption of a raspberry Pi




The Raspberry Pi relies on a linear regulator for its 3V3 rail. This dissipates a third of the energy as heat, which is a bit of a waste, if you want to power your Pi from an battery. Our solution: Replace the linear regulator with a $2 switching regulator from ebay. We also used another regulator for the 5V power, to test powering a Pi from a car battery.

One of our switching regulators

Initial measurements

We tuned our benchtop power supply to 12V DC, and set the current-limit to approximately 400mA. Then we adjusted one of the switching regulators to 5V, and labelled it. We gave our Pi an SD card, and ethernet connection. We then hooked up the power to the Pi, on its GPIO header (GND on pin6, 5V on pin2). After booting, the current consumption from the benchtop supply stabilized between 190 and 200mA, which translates to a power consumption of about 2,4W.

Slicing the Pi

To make sure the linear regulator stopped wasting power, we completely removed it from our Pi, with a hot air gun. To do this, we griped the regulator with some metal tweezers, lifted the Pi about a centimeter, and then blasted the regulator with air at 422 degrees Celsius. After a few seconds, the Pi dropped to the table, and the regulator was removed:

There used to be an LM1117-33 at this spot...

Decorating the Pi


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