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Logic to 12 Volt Switch




I had some TIP125 and some 2N2222A transistors around, and needed to switch 12 volts at around 2 amps using the outputs of a microcontroller running at 5 volts. These transistors work well for this. True, a power MOSFET might work even better, but here is a circuit you can most likely make from your parts box. As an added bonus, the current used to drive the TIP125 also lights an LED. The input in this circuit works with standard TTL logic levels. Here is a picture of the breadboarded circuit driving a car turn signal bulb:



Here is the schematic:



The schematic is in fig format. Here is the fig file. For more info on Xfig, the program that generated this, see Xfig.org.



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