Heatsinking the regulator

When I turn on a LCD and 24 LEDs (RGB ones showing white), USB power starts to fail and when I use the power pack the regulator gets rather hot.

Has anyone heat sinked the regulator before? Whats the best way to do it?

hi @cheater that is a pretty tiny regulator; on the Diecimila it is good for 800Ma max, close to what you would get from the USB port too.

To reduce heat you could: - reduce the external DC voltage (i.e. using 12V means about 6 watts of heat at 1A, whereas using 7V means 1W of heat, very approximately) - use an external regulator to generate the supply voltage for the external voltages.

Putting a heatsink on the Diecimila is probably not a good idea, as the tab is connected to V+

D

I was using 9v. I've knocked it down to 7.5v. Adjustable power packs rock. :)

I wonder if I could desolder it and replace it with a full sized regulator. Might just build a Atmega32 from scratch and use that for heavy stuff.

For circuits with especially heavy power consumption, you might think about separate regulators for the arduino (already on-board) and your extra circuits (heatsinked separate regulator.) Only the grounds have to be common. Alternately, you can find a 5V regulated external power supply, bypass the regulator, and use it to power everything (cheap ~ 5V 2A regulators are showing up in assorted surplus venues: http://www.goldmine-elec-products.com/prodinfo.asp?number=G16479, for example.)

(One reason your regulator is getting hot may be that your "adjustable" supply is not regulated, in which case it could be putting out significantly greater than 9V on the 9V setting (it would settle down to 9V at the full rated current. Maybe.))

I have a large amount of different Dc wall warts that i have scavenged from various places. One day i decided to meassure their outputs. Out of the 20 or so i tested ONLY ONE was putting out the voltage printd on it. All the others was putting out a higher voltage. One was markd as 9V and was in fact putting out over 16V.

So never trust a wall wart, ALWAYS use your meter and check it. Or you could fry whatever you are powering with it.

MikMo
http://www.mikmi.dk

One was markd as 9V and was in fact putting out over 16V.

Wow. Mine is a high quality (aka expensive) adjustable (6v, 7.5v, 9v and 12v) power supply. Not sure if its regulated or not. Probably isnt.

I'll measure its output when my multimeter comes tomorrow.