I am using a Sanguinololu to control my Huxley, built from a kit supplied by RepRapPro which uses a 19V laptop type power supply. It works - no problem.
I am looking to power a display from the Sanguinololu which will draw around 150mA through the onboard 7805 voltage regulator - the display requires a 5V supply which I will take from the expansion pins. My concern is that drawing this amount of current may generate too much heat for the 7805 regulator to cope with as it will need to drop 14V rather than 7V which would have been the case had I been powering the board from a 12v supply.
(In fact, I HAVE tried connecting the display to the board and the 7805 gets VERY hot!).
I would appreciate comments on this arrangement please - in theory, the 7805 should be able to cope with any load which does not demand more than its maximum current limit - 1A - but how big a heatsink do I need? Space is limited.
Thanks in advance,
Alan
EDIT: Been doing some reading up and the answer is .... not very much current without using a big heatsink- not enough to provide me with the 150+mA I would need. I'm now looking for alternative solutions to provide me with 5V without using the onboard 7805. Initial thoughts are to take the 19V (from the 12V expansion pins) and then use - off board - a 7812 to supply a 7805 - effectvely sharing out the reduction in voltage. Any electronic gurus out there who can suggest a different solutions?
Edited 1 time(s). Last edit at 02/05/2013 05:37AM by Alzibiff.
