12 volt to 3 volt?

[sleepgsr]

Hello All,

I've been a lurker on the forum for over a year and never have posted yet That is probably because of all the topics and posts from others covered any questions I have had.

I've added a portable hot water heater to my pup. Its an on demand type so as soon as I turn on the water, it fires up and heats the water. It runs on propane and takes two D batteries wired up in series so it uses about 3 volts. Does any one how I can use my 12 volt trailer power and reduce it to 3 volts to run this without having to use the D batteries. I am confident I can do the wiring but don't know what type of device I need to reduce from the 12 to 3 volts. Also are there any other power considerations the I need to know besides the voltage.

Thanks for your time,
Vince

 

[sloth]

You need a DC-DC converter, sometimes called a buck converter. Other considerations would be to make sure it can provide enough amps but if it is currently using 2 D cells, the amperage draw is probably not very high.

-Mike

 

[Abqlloyd]

I'm also a long-time reader. I'd use a simple 3-pin, IC regulator. Shouldn't cost more than $3.00. Try Radio Shack locally, or Sparkfun or Digikey online.

 

[sleepgsr]

Thanks alot.

 

[DaveInDenver]

The LM317 is the adjustable linear regulator that Radio Shack probably has. This will get very hot dropping 12V to 3V. I would use a 78L03 or the drop-in replacements if you can find one.

You could also use a 7805 or even a simple BJT regulator with a zener divider, but the 78L03 (or78L33) would be better.

The slick way would be use one of National's LP29/39xx (or similar) small footprint switchers that you could build a little circuit around.

 

[Abqlloyd]

If you want a small circuit-based solution check out Dimensional Engineering. They cater to the R/C market. I've used their stuff and it's high quality. Hope I didn't violate any rules. I have no affiliation with them.