# convert from 12 volt to 6 volt

Solar Expert Posts: 116 ✭✭✭✭
I feel stupid asking this, but I've forgotten & can't find anything on the internet. I want to use a 6 volt fountain water pump on a 12 volt system. I can't find a tiny 12 volt one, but lots of 6 volt ones.

thanks

• Solar Expert Posts: 264 ✭✭✭✭✭✭
Re: convert from 12 volt to 6 volt

Search for something like this http://www.pacificcable.com/Picture_Page.asp?DataName=901-800, whether this one with 800ma is enough for the pump.
GP
• Solar Expert Posts: 116 ✭✭✭✭
Re: convert from 12 volt to 6 volt

Now I feel even dumber than I did asking. I've got several of those about.. somewhere. Nice thing about moving, I'm finding all kinds of things.

Thank you.
• Solar Expert Posts: 116 ✭✭✭✭
Re: convert from 12 volt to 6 volt

I was actually thinking more along the lines of if I put a resistor equal to the resistance of the pump in parallel or if I put a resistor in series. One way should half the voltage and the other should half the current ?? It's been a long time since I did any of that kind of stuff. I really prefer that to using a plug in deal.

found it: http://www.play-hookey.com/dc_theory/voltage_divider.html
• Solar Expert Posts: 9,572 ✭✭✭✭✭
Re: convert from 12 volt to 6 volt

When converting voltages, there will be losses. Using a resistor, you get inaccurate voltage if the load deviates from the original calculation. If you use a LM7805 regulator, it's a smart resistor, but you still waste 50% of your power.

You could use 2, 6V pumps in series, and pump 2x the water.

And then there are Switcher Power supplies, which run 90% efficient, and cost a bit more. They can convert from 1 DC voltage to a different voltage
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