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 obtained from an English magazine from 1977. It is a toy musical instrument that...
The presented circuit uses common transistors that can be the BC549. The maximum amplitude of the...
This is the receiver for the previous circuit, also found in 90s Radio Electronics. The circuit...