There are a few parts necessary, but all of them are pretty easy to get.
Part Name Use Cost Where to Find Halogen Lamp light src $6 Lighting store/Online MR-11 Socket for lamp $6 Lighting store/Online Halogen Torchiere housing $0 In trash Solid Core/Stranded Wire Wiring circuitry & Battery $0-$5 Phone wire and thin stereo hookup is fine Perfboard circuit substrate $4 RadioShack, etc LiIon Battery power src $20-$60 EBay, electronics store
The rest are electronic components, all available from DigiKey.
Part Name Part Number Cost (each) Rail-to-rail opamp LMC6482IN-ND $2.05 Power P-FET IRF9Z30-ND $1.28 5.1 Zener 1N5231BDICT-ND $0.36 10K Pot w/Switch 270X232A103B1B1 $3.48 0.1ohm 1/2W sense resistor* 605HR100-ND $0.42 Mini Banana plugs J457-ND $1.42 DC Jack (for battery connection) CP-102A-ND $0.38 DC Plug (for battery connection) CP-002A-ND $0.38 Various resistors Search website $0.10

* If you're using a 10W or less bulb, 1/2W is ok. Otherwise, 1W is best.

This guide was first published on Apr 21, 2013. It was last updated on Apr 21, 2013.
This page (Parts) was last updated on May 25, 2020.