Step it down a notch

A project log for ISS Lamp - NTP clock - Artpiece

My "standalone" take on the ISS lamp lights up when the spacestation is overhead. It doubles as a NTP controlled clock.. with a VFD display.

RobottoRobotto 08/14/2014 at 11:030 Comments

The power dissipated in a linear regulator is equal to the current multiplied by the voltage drop (P=I*ΔV) 

In my case the output voltage from the ethernet shield is 12V, and the arduino needs 5V, which gives a ΔV=12V-5V=7V

The current draw of my entire setup is appoximately 500mA (0.5A) so the power in the regulator would be about: P=7V*0.5A=3.5W which is way more than the tiny regulator on the uno could handle.

Therefore i've had to replace it with a 7805 regulator in a TO220 casing with added proper cooling... After a couple of months of running quite warm I decided that I was running it too close to it's maximum rating and exchanged the regulator with this step down converter from Now everything is nice and cool(er).

Arduinos are nice and easy to modify; Since they're open source the schematics and design files (open them with eagle) are freely available, so you can easily learn where to (de)solder :)

BTW: The links to design files and schematics are for the first version of the Uno which is the one i use, for other (current) versions look at