In the figure we have a basic shield circuit with TTL to TTL optical isolator. For the emitting LED the voltage can be different from 5 V.
This circuit of a voice-controlled switch, Vox or sonic switch was obtained in a Popular...
This circuit appeared in the July 1969 issue of Radio Electronics magazine. The sensor is an LDR....
This circuit of two transistors was found in a Japanese magazine in 1967. The transistors are made...