[SOLVED] Thrifty voltage regulator, increase in current?

[neazoi]

Hello I have tested it with a BD436 instead of a bc557 as a regulator. It worked fine up to 150mA consumption current! As current drawn increased to more than 150mA the output voltage dropped gradually.

The BD436 is a much more powerful transistor, I should expect more than 1A. Do you know what causes this problem?
Maybe the gain of the driver transistor in the feedback loop is not enough? Should I try the darlington approach in post #1 instead?

 

[betwixt]

The circuit is inherently self regulating so the only reason it can't produce more output current is lack of bias current. Try reducing the value of the 6.8K resistor down to 1K and the 820 K resistor down to 47K. Let me know if that helps.

Brian.

 

[neazoi]

The circuit is inherently self regulating so the only reason it can't produce more output current is lack of bias current. Try reducing the value of the 6.8K resistor down to 1K and the 820 K resistor down to 47K. Let me know if that helps.
Brian.

Yes this worked! I do not how much current more can I draw but it worked up to 200mA that was tested.