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 was found in a Popular Electronics from the 90s. The frequency depends on the...
This circuit consists of a “zero crossing detector” that provides a rectangular output signal...
Low power RF transistors such as the BF494 or BF495 and even those in the BC series can oscillate well...