This circuit was found in a documentation of the 80s, having didactic purpose. For R1 values between 10k to 1M can be used. Transistors are general purpose types.
The presented circuit is used in Power supply to increase the voltage output. The voltage output...
We find this automatic battery charger in an 80s ON Semiconductor circuit and application manual. Bridge...
Found in a 2005 Linear Technology application manual, this circuit monitors the current in a load...