Thread: What do I need to bring 12v down to 6-7v?

I dont know if it would work for your application, but a common method of under-powering 12v case fans is to use the +5v rail on the molex as the ground for the fan, resulting in 7 volts to the fan.

http://www.techtastic.ca/articles/12to7.html

Ive done it before for fans in my case and it works fine for them.

Don't do what moondog51 is saying... that will indeed result in 7 volts across the power supply of the adapter.. BUT, your reference, or ground, will be 5 volts. The output of the soundcard or whatever you're getting your source from will have a reference of 0 volts, and a high voltage of 5 volts. This'll likely screw something up.

You sure you need 6-7 volts, and not just 5 volts? If 5 is fine, you can use the 5V power rail on the PSU. It might not hurt to try it... from my experience (and someone please correct me if I'm wrong), it's always fine to try to provide too little voltage to test something, rather it's much worse to try to put in too much voltage to see if it can handle it.

and to add to that, that trick should work fine for something like a fan, simply because the fan only cares about the voltage across it... it's not getting another signal (audio, in this case) to use that reference to compare to.

Originally Posted by wizawuza

Don't do what moondog51 is saying... that will indeed result in 7 volts across the power supply of the adapter.. BUT, your reference, or ground, will be 5 volts. The output of the soundcard or whatever you're getting your source from will have a reference of 0 volts, and a high voltage of 5 volts. This'll likely screw something up.

You sure you need 6-7 volts, and not just 5 volts? If 5 is fine, you can use the 5V power rail on the PSU. It might not hurt to try it... from my experience (and someone please correct me if I'm wrong), it's always fine to try to provide too little voltage to test something, rather it's much worse to try to put in too much voltage to see if it can handle it.

Underpowering is generally not too bad. It can cause long term problems with components, but to test it to see if it works, certainly you can do that will little risk.

You can try finding an adjustable regulator used in a car. They usually plug into the cigarette lighter socket, and have a switch that will change the voltage. Another option is a Automotive Laptop Charger. They are sometimes refered to as "Universal" blah blah blah They are often times adjustable (The one I got from Radio Shack is) They are like 30 or 40 bucks. They can, however, supply a significant amount of current, say 3 or so amps, with out a problem. Whatever you decide to use, you must make sure that your supply can provide enough current. If not, you will have problems.

Michael

Don't know why you need +6V. But from the car 12V two condensers and a voltage regultator you would have 6V.

The electrical schema is at the end of the PDF at:
http://www.alldatasheet.co.kr/datash...UTCLM7806.html

Steve