This optical counter was found in a 1964 Electronics Design. It makes use of an uncommon optocoupler today, using emission lamp and a phototransistor.
This ultra-simple 9 V power source was obtained in an Argentine publication of the 1970s, but it...
This circuit is from 1967 General Electric documentation. It uses SUS which are not very common...
This differential amplifier, found in a 1964 Electronic Design, has a gain of 30. The setting can be...