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.
May 2017 - Panasonic's new APS1 series of optical couplers with 3 750 V insulation and up to 50...
Found in an EDN from the 90s, this circuit uses an electret microphone. The output can be used to...
The purpose of this circuit, found in a 1994 documentation, is to provide resources for testing...