This circuit serves as a reference for the components used and the time. The circuit is from 1967 RCA documentation. MOSFETs from that time are used.
This circuit, from a publication of the 1970s, can compare the intensity of two light sources,...
This 1965 Philips circuit uses old company transistors like the BFY51 and BFY50. The circuit is...
It can be obtained from Mouser Electronics new crystals for surface mounting from AVX with...