This is a really simple project which takes a wall wart and using a Tic Tak (Tac really) box makes a cheap, easy, useful, power supply; in a hurry. In this instructable I am going to try to write a little and photograph a lot. If you are in a hurry, the picture here pretty much says it all.
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Step 1: Wall Wart and Connector
Start with a wall wart or computer supply of some sort. Pick a voltage and current that exceeds your needs. We want to use a standard power connector ( that is also common ). Get some of https://www.amazon.com/gp/product/B00LFDSM6K/ref=o... or these which I may like better for this project https://www.amazon.com/gp/product/B00PZVDPTM/
If you wall wart fits the connector great, if not cut it off ( with a few inches of cable if you want to be able to reuse the plug ) and replace it with one of your new standard plugs. I used some heat shrink tube, hot glue may in some ways work better, or just forget about insulation and take a chance.
Step 2: Regulator
We need a voltage regulator to get the voltage we want ( as opposed to what comes out of the wall wart ). Nowadays these are very cheap and energy efficient.( something like: http://www.ebay.com/itm/3A-LM2596S-Step-down-Regulator-BUCK-DC-DC-Voltage-Module-Adjustable-Power-EFFU/112224576688 ) A few wires, connectors, the Tic Tak box and we are done. Do not forget to adjust the regulator to the voltage you want ( but removing and readjusting is easy ). I like to label the regulator. Open office file attached.
Step 3: Binding Posts
This is still pretty much a wall wart, but now at the right voltage. Next binding posts. Remember red is positive. Use of the binding posts is optional.
Step 4: Battery Eliminator
If your 9 v batteries are dead, try this using a clip from an old battery. Use with a supply set to 9 V. Make sure polarity is correct. I insulate the back with hot glue.