This circuit is from a 90s Radio Electronics. The resistors must be precision types and the transistor is a general-purpose type. The operational admits equivalent.
This circuit with two operating modes was found in the September 1989 issue of Radio Electronics...
This circuit was suggested by old French documentation, but it can be used as a shield, in which...
This well-crafted speed game setup for two competitors was found in a 1998 Poptronics. The circuit...