Adj Breadboard power supply kit
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Adj Breadboard power supply kit

by ericbnyc on Sat Nov 17, 2012 4:41 pm

I decided to build the Adafruit adjustable breadboard power supply (http://www.adafruit.com/products/185) unfortunately perhaps, during a week when the full kit was out of stock. I sourced the components myself from a couple of popular vendors and bought just the board from Adafruit, and assembled it myself. Now that I'm done, one side works fine, and one doesn't.

The pins marked "VO" next to the red led, and the inner "Vout" pins next to the potentiometer work correctly, delivering 3.3v, 5v or adjustable voltage as determined by the voltage selector switch. The pins on the opposite side labeled"Vi" or the inner adjacent pins next to the potentiometer labeled "Vin"as well as the two screw down posts in the back (behind the red led) all deliver 15 volts (from a 15v wall wart) no matter what voltage switch selection or potentiometer setting I use.

Anyone every build this kit and see similar behavior? Any tech support read these posts, and have a suggestion? I've searched the forums here and haven't found any relevant posts.

I took a very close look using both x5 and x10 magnifiers and I really don't see any solder bridges. I'm a little disappointed, as I was hoping to look at this as the next step in my hobby - sourcing the parts myself at least, if not my own engineering. I simply followed the parts list provided on the power supply 'make' page. Ah well. Any suggestions to fix this appreciated.
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Re: Adj Breadboard power supply kit

by adafruit_support_mike on Sat Nov 17, 2012 10:37 pm

Actually, that's how it's supposed to work. Take a look at the "Use it!" page from the instructions:

http://www.ladyada.net/make/bbpsup/use.html

and you'll see that the Vo/Vout lines are the regulated ones, and the Vi/Vin lines (plus the terminal blocks) are unregulated.

BTW, the terminal blocks are for input, not for output. If you're working with a circuit that already has its own power supply, you can run wires into the terminals rather than trying to fake some kind of connection through the barrel jack.

So, while it may be doing something you didn't expect, the good news is that it's doing exactly what it was designed to do, and you nailed the "sourcing the parts and doing assembly" process.
When you void a product warranty, you give up your right to sue the manufacturer if something goes wrong and accept full responsibility for whatever happens next. And then you truly own the product.
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Re: Adj Breadboard power supply kit

by ericbnyc on Sat Nov 17, 2012 11:27 pm

Thanks Mstone.

Son of a gun . . .
So, kudos to me for sourcing and assembly, but major fail in reading documentation fully and properly. It's been said we learn best from our mistakes. Well, this was a real lesson!

Thanks for answering, it's nice to now I at least put it together right.

Tx,
-e
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