Using the 555 and 4020, this timer was found in the July 1994 Radio Electronics magazine. The relay is voltage-dependent, and the transistor is general purpose.
This circuit was obtained from documentation from the 90s. The solution that can be found...
This receiver powered by the signal captured by the antenna (which must be long) was found in...
This circuit measures the temperature through the voltage drop across a diode. The circuit was...