This circuit was found in documentation from the 90s. The transistors can be general-purpose equivalents. The circuit has two versions, one that drives LEDs and another that drives a relay as a load.
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...