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Circuit Supply Splitter with IC 741& TIP41,TIP42
If you must modify a place power supply. usual to dual power supply positive,negative,GND(0V). I introduces to try use. Circuit Supply Splitter with IC 741& TIP41,TIP42. When see the detail in the circuit make output of the circuit is pin GND(0V) the part is pin positive be +V part [...]

This is a Constant Current Source LED Driver, When the LED driver Upper-NPN is driven by a voltage thru 4.7K the LED lights up. Assume that the Lower-NPN at bottom is absent. The current via LED and NPN is limited by R. 20mA may be ok 15mA even better. Or LED blows even transistor goes.
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