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Originally Posted by PocketBrain
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Parts:- The case came from a laser/pen/stylus that I bought at RadioShack.
- Charging socket from RadioShack. $2.59 for a 2-pack. I had it on hand already.
- 7805 +5VDC regulator was from RadioShack: $1.69
- Plug from RadioShack, was taken from my USB hub/charger adaptation. $2.59 for a 2-pack.
- 6-AA battery holder from jameco grab bag. :-)
- Batteries from Target. Ray-O-Vac 2500mAH-AA, $8.99 for a 4-pack. No sales tax, hurricane tax holiday! Extended cost for 6 batteries = $13.50.
Total cost: $17.78. Or you could consider it $20.00 for the parts that came from supply.
<SNIP>
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Excellent stuff!
However, please be aware of two items when using analog voltage regulators:
1. Heat dissipation - Your dropping 8 volts across the regulator. If you're pulling 1A through it, it's dissipating 8 watts. That's quite a bit of heat and the regulator could go into thermal shutdown if it's not heatsinked well.
2. 780x regulators are famous for being unstable (ie: the output oscillates) if you're driving a load a few feet away. It is common practice to place a 1uF tanatalum capacitor at both the input and output of these regulators to prevent any instability. Just make sure you observer correct polarity on the cap.
Keep those ideas coming!