This circuit uses a 100 kHz crystal, but nearby frequencies can be obtained with appropriate crystals. Components are still common today.
The circuit is from an 80's publication. The operational ones used are of the time, and must be...
This circuit was found the Optoelectronics Sourcebook by Texas Instruments. Any phototransistor...
The circuit shown in the figure is suggested by Micrel, based on the MIC2570 boost voltage...