Looking for a 6V power supply

[simplechamp]

I want to get a little power supply that I can plug into the wall and use to test RC electronics. I would really love to have a nice adjustable CC/CV supply, but I'm not ready to spend the money at this point.

I did a search on Ebay and found some cheap AC adapters that output 6V and rated anywhere from 1-7A (depending on price). Would one of these work OK for basic usage?

For example, this is one I'm thinking of getting: http://cgi.ebay.com/Genuine-UNIVPOWE...item5ade49cc7d

[Shonen]

cheap AC adapters tend to output well over their rated voltage unless they are loaded significantly. One of my cheap 5v adapters throws out well over 7v open circuit...I would not trust that as is, use a regulator. An LM7806 at the adapter output should do the trick, unless you're pulling over an amp continuous testing things.

I use several modded pc power supplies for my projects, the 5v out rail is perfect for servo testing. If you have HV servos, you can get 7v from using the 12v rail and 5v rail. PSUs have protection circuitry so I would trust them more than an uber cheap wall wart. (:

[What's_nitro?]

If you're after a low voltage/current source why not use a CC BEC? Then it'll be adjustable and portable, too.

It could run on NiXX cells and then you don't need to worry about LVC.

I suppose you could buy one of those AC adapters to power it from the wall in the event you didn't have access to a charged RC pack.

[bdebde]

I just keep a simple 4 AA cell holder... don't even have to plug into the wall.

[BrianG]

For electronics prototyping, I have a homemade breadboard setup with a modded PC power supply as the supply. I only use the 12v output of the supply, but to get adjustable voltages, I then use a LM317T with a large pass-transistor mounted on a large heatsink to get for ~1.5 to ~10v @ 10A.

You have a drop-out with any linear regulator, so make sure your supply is rated for at least 2v higher than any voltage you will want. To get around this, I use a switch that selects 12v (direct from the PS) or adjustable (from the regulator).

Also be aware that the use of a linear regulator with high differential voltages and high output current, while simple, can create a lot of heat. If I am drawing 10A @ 3v for something, the heat will be (12v-3v)*10A=90w.

The use of a CCBEC Pro would be perfect, except you can't quickly and easily adjust it; you have to hook it to a PC. It would be really nice if you could hook up a pot to it somehow to adjust it...

[bruce750i]

I just bought one of these 3v-13v pot adjustable switcher to play with, good for 25watts. http://www.dimensionengineering.com/DE-SWADJ3.htm

[simplechamp]

Thanks for the input guys. I'm going to pick up a 12V AC adapter and a Castle BEC. I want to be able to plug into the wall rather than use a battery pack, and I'll be able to use the CC BEC in other applications if wanted.

EDIT: Is it OK to use the CC BEC with the AC adapter as input rather than a battery?

[BrianG]

Originally Posted by simplechamp

EDIT: Is it OK to use the CC BEC with the AC adapter as input rather than a battery?

Only if the output of the AC adapter is DC (some output AC). Also for better results, you may want to add ~1,000uF or more of capacitance between the adapter and BEC. Doesn't have to be low-ESR and should be rated for 25-50% more voltage than you plan to use. For 6v, 10v caps are ok.

[simplechamp]

Yeah I will make sure it is a true DC output, and I have a whole box of assorted caps, they are all low ESR but that's fine.

So you are saying add the cap in parallel with the BEC input, like adding a power cap to the battery leads on an ESC?

[Shonen]

^ yep. will help with AC switching noise filtering, but because it's 120Hz, ESR isn't as important as with 10KHz+