The presented circuit uses a PNP transistor, which can be the BC558. Observe the polarity of the supply. The circuit is suggested by Texas Instruments opto-electronic documentation.
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...