The circuit presented was suggested by Texas Instruments in an opto-electronics manual. The transistor can be the BC548 and the supply voltage depends on the application.
The circuit shown is from the 1994 National Semiconductor Linear Applications Handbook. The...
This precision circuit, which also functions as a bridge, was found in a February 1967 Popular...
This circuit was obtained from a Hands On-Electronics, an American magazine from January 1987. This...