Hi all,

I am looking to make a DC to DC converter to drop the car's 12v to a clean (filtered) 5v and I am not really sure where to start and I hope someone in here can point me in the right direction.

I found one web page that suggested using a LM317 regulator to get the 5v and using a capacitor between ground and the output of the regulator to clean the output voltage up a little.

I am doing all this to power a micro controller in the car.

Thanks for you help!

 

If you want it clean, then yes, a capacitor is the best way to do that.

I would personally use the LM7805 to regulate 5v from 12v. It's simple, and here is a site explaining it and capacitor use to clean it up.

http://www.iguanalabs.com/7805kit.htm

You might want to buy a fan and/or a heatsink to help cool the LM7805 though, I would assume it creates some heat.

 

Thanks for the link! There is some good info there.

hmm, unfortunately i want it to be on all the time the car is on and having to run fan really wouldn't work. a heatsink might be ok, but there had to be a way to not have either of those...

 

I'm not sure on how much heat would be created. With any voltage conversion, there will be heat created. (I assume, according to the my general understanding.) I'll look around a little bit because I need to do the same thing for LEDs.

 

I have built that circuit before to power a camera, and you for sure want to use a heatsink. I toasted the first one I built, but I mounted the second one to a 3x3in Al plate, and it lived.

 

Yeah I am actually trying to power a micro controller to run a programmable LED shift light. I want the light to operate like the sequential ones seen in many race cars. I used to have a Datatool Revlight in my Interga for track days and it works great (I could focus more on learning to drive rather than on the tach), but Datatool does not make the Revlight anymore.

Denver - thanks for the heads up. The product I mentioned above was contained in one small package (it was a flexible PCB potted in silicone to protect it) with one hook up for the rpm signal from the tach, and a ground and 12v power hook up. I assume the voltage drop was done on the board, otherwise that system ran on the noisy 12v.

Lots of homework to here I think....

 

https://www.evolutionm.net/forums/sh...d.php?t=317980

Look at that. It might help.

 

EricH - the is fantastic! Thanks for your help!! I will post more of my project in a separate post as things move a long.

thanks again!

 

dumb

 

let's keep this constructive, cool?

 

douche....

On Topic:

I wouldn't have thought a 5v reg would have created enough heat to smoke without a sink, but....it seemed to have been a problem for denver so....

That said, when mounting up your reg to a heatsink, I'd be careful not to forget some heatsink compound. You might lose the effectiveness of the heatsink if you aren't getting a good contact between the two surfaces. You should be able to pick up some compound from compUSA or an online vendor such as NewEgg if you can't find it locally.

 

good idea.