This circuit is from the 80's but uses common components today. The relay is voltage sensitive according to the power supply used. Transistors may be general purpose types.
We found this circuit in a 1965 Electronic Design. Transistors are still common but admit...
This very low consumption circuit can be powered by a solar cell. The time indication is given by a...
We found this circuit in a documentation from the 50's. The transistors are germanium types. The...