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No.300 ohm = 72.81ma
250 ohm = 86.4ma
200ohm = 106ma
I think these figures are in the ballpark
The TIP120 darlington datasheet shows that its base to emitter voltage loss is 1.25V when its collector current is 100mA (25mA for each of the 4 strings of LEDs).I am wondering how one determines the max voltage available at the emitter??
In audiogurus last post he mentioned that it was only 10.05v
how is this determined?? from the spec sheet or ??
If the polarities are swapped then a PNP darlington would work exactly the same as the NPN darlington circuit.1. Why NPN darlingtons used as source transistors, wouldn't PNP be called for?
For a very low base current so that the series 10k resistor and 100uF capacitor can make voltage ramps.2. Why Darlingtons for only a couple hundred mA? Are there more LEDs than illustrated?
A Mosfet cannot be used as a follower unless a voltage booster is used for its gate voltage.3. Why not a simple power MOSFET like IRF510 which should have no problem driving buckets of LEDs.