This TTL counter was found in the March 1991 issue of Radio Electronics magazine. The circuit is part of a larger project and must be powered by a 5V voltage.
This preamp version uses BC109 transistors that are older versions of the current BC549 in plastic...
This circuit was obtained in a technical documentation from the 70s, but it can be assembled with...
This stepper motor control was originally designed to use a PC's parallel port and is quite simple...