Quote: Originally Posted by DJSmiley
Some notes:
1. A regular 7812 only allows up to 1A output. For more output, look for a 78S12, that one is able to handle 2A.
2. Heatsink IS requires, bigger = better, ok, but in my case, an old CPU fan does the job perfectly.
3. The capacitor on the input is almost useless, since its directly on the battery. To give it a better use I suggest adding a diode before it, so it will only buffer the 7812, and not your lights/hu/and so on. However, adding a diode causes a decrease of the voltage with about 0.7V.
More important: For good regulation the 7812 requires an input voltage of about 2-3V above the desired output voltage. So its very doubtfull if this will work in the car, since the car voltage IS 12v, and, during drive, about 14V...
Better use a low-drop regulator, since they require less input.
It does need 2 volts to work optimally, but most LCDs, (Xenarc and Lilliput anyway) say they work with 11v and up so 11.5~12v from the 7812 should be fine. As far as the 78S12, there is anything wrong with using it,, but a 7812 is easy to pick up locally, (ie Radioshack)
It would almost certainly work.I'm not powering my lcd yet with one, but my lighting system uses three of them and I've got a perfect 12v delivering about 1.5 amps through each (I got a 7812 with a slightly higher current capacity).
What would a diode accomplish on the input?