Here
is a very useful workbench lighting unit for electronics hobbyists. The
portable inspection lamp circuit consists of an on-board voltage
regulator and a high-bright 5mm white LED. Any 9 to 18 volt dc rated ac
mains adaptor, capable to source about 100 mA of output current can be
used to power this portable inspection lamp.
After construction the led workbench light circuit should be enclosed in a suitable plastic bottle cap as illustrated here. The miniature lens shown is an optional component. In the prototype, plastic made lens lifted from a discarded torch was used!
LED workbench lighting lamp circuit schematic
The
adjustable 3-pin voltage regulator IC1 (LM317L) in TO-92 pack, is here
tuned to supply an output of near 4.5 volt dc. This supply is directly
fed to the white LED (D2) through the current limiter resistor R3 (51
Ohm). Diode D1 (1N4001) works as an input polarity protection guard and
two small electrolytic capacitors (C1 and C2) connected at the input and
output pins of IC1 improves the overall stability of the regulator
circuit. Use a standard RCA or EP socket as the input terminal J1.