This circuit was found in a Popular Electronics from the 90s. The counter circuit is not common today. The circuit can be programmed for hourly intervals, according to the values of R4 and C2.
In this circuit, the current capacity doubles, but is still of the order of microamps. The...
Although not using transformers, this amplifier may have difficulty mounting if the original...
This interesting benchtop circuit was found in the May 1977 issue of Radio Electronics magazine. The...