6.5 Volt 3 amp regulator

136

01:49:06

10 - 40Volts input , 6.5 Volts output at 3 amps.

Transistor type is BD681 NPN (Darlington).

published 10 years ago

ismailkhan

10 years ago

What is the transistor number...?

billoute720

10 years ago

Doesn't work cause when you adjust lamp voltage to 6.5V, output voltage drops to 4.9V. You should use 2 transistors in Darlington configuration to get a higher current gain :)

dkobe

10 years ago

Actually the default emitter resistance of 1 ohm is way too high. r'e = .035÷emitter current. So, .035÷3amps is about 11 mOhms. So set the emitter resistance to .011 ohms and your ckt works fine.

Matus

10 years ago

Or you should put 22R resistor before NPN transistor (T1) and put there PNP transistor (T2) connect its base between collector of T1 and 22R resistor, connect T2 emitter to + and connect T2 collector to T1s emitter :) it work to higher voltages than 40V (max.U transistor Uce)

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