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An LED tester soldering kit
An ideal constant current driver supplies a specific amount of current regardless of supply voltage and other environmental conditions, like temperature. The LIGEMDIO's simple circuit does this reasonably well using only two NPN bipolar transistors and two resistors. It allows the driving and testing of many types of LEDs, through-hole and surface mount.
The name LIGEMDIO is made of the first letters of Light Emitting Diode, LED.
LIGEMDIO was project #8 of the Boldport Club.
2x 1KΩ resistor, Multicomp MF25 1K
1x 33Ω resistor, Multicomp MF25 33R
1x USB connector, Multicomp MC32603
1x Orange LED, Kingbright L-9294SECK
2x NPN BJT, Fairchild PN2222ATA
1x 3.3µF electrolytic capacitor, Multicomp MCMR50V335M4X7
1x Lovely circuit board
The circuit relies primarily on the near constant voltage drop between the base (B) and emitter (E) of transistor T2 to keep the voltage across R1 also 'constant'. In turn this keeps the current for the LED 'constant'.
Refer to the infographic for further circuit and assembly information.