This SCR relaxation oscillator was found in an 80's Electronic Design. It flashes a small incandescent lamp in frequency that depends on the capacitor.
This 1960s Signalite circuit uses two SCRs to achieve full wave control. The trigger elements are...
This shoot-to-target game uses well-known CMOS circuits and the player hits the LED by squeezing...
This TTL circuit can be used as a shield. The frequency can be changed by changing the capacitors. ...