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.
This circuit is from a documentation from the 90s. The transistor can be any general-purpose FET...
Found in an Elektor from the 90's, this double door-bell drive circuit switches a relay by...
Using a CA3130, this circuit generates signals from approximately 550 kHz to 1.6 MHz using a...