This TTL circuit consists of a frequency divider or converter that has values selected by a switch. The circuit is from Radio Electronics from December 1980 and must be powered by a voltage of 5 V.
This circuit is from old European documentation. R1 depends on the output voltage of the...
This SCR circuit activates a buzzer when triggered. The circuit is from a Popular Electronics from...
This 130 V drive uses an integrated circuit not very easy to find, which is the LM143. The circuit is...