This telephone circuit was found on a 90's EDN. It keeps a flashing LED to indicate that there was a call in your absence. The components admit equivalents.
This VFO (Variable Frequency Oscillator ) has the output frequency controlled by a potentiometer....
This well-crafted speed game setup for two competitors was found in a 1998 Poptronics. The circuit...
To obtain more output power from an operational amplifier, we can use a transistor, as shown in...