Transistor as switch, power saving from switching current source?

Thread Starter


Joined Oct 12, 2013

Are there any complications from making the resistance as high as possible to limit power consumption from the control source? I can make an identical circuit and put 50k into R(b), receiving a negligible current loss for the LED/I(CE), and greatly improving the power consumption for the switching control source.

Is the gain of the transistor a factor in using a transistor as a switch?


Joined Mar 14, 2008
Yes, the transistor gain is a factor. Good engineering practice is to use a base current no lower than 1/10th of the collector current to fully turn on a BJT transistor.
If you want a lower control current than that, you could use a MOSFET which requires zero gate current to turn on.