This timer was found in Japanese documentation from the 1960s. The transistor can be replaced by an equivalent and the relay must be of the sensitive type with voltage according to the power supply.
We found this circuit in an English magazine in 1975, but it can be easily assembled, as the...
Found in a 90s Popular Electronics, this circuit uses a 741 to generate frequencies from 0.1 to 30...
This circuit is from an 80's documentation. The circuit makes use of a component of the era, the...