The TTL Clock, as name suggests, is implemented entirely using 74xx series integrated circuits. Compared to other clocks, this clock does not use any programmable devices (such as microcontrollers), or specialized clock integrated circuits.

Most integrated circuits used in the clock are TTL-LS, 74LSxx series ICs. The only exception is the 74HC4060 frequency divider, which is a CMOS IC. The integrated circuits are arranged on the board in a neat grid, this adds to the "vintage" clock appearance.

The clock uses a 32768 Hz quartz crystal for the time base. The crystal frequency is divided by 2^15 and the resulting 1 Hz signal is fed to the seconds counter, the output of the seconds counter is connected to the minutes counter, and that of the minutes to the hours counter. The clock uses two RS flip-flops with switches connected to the inputs and two multiplexers to setup the minutes and the hours. Another switch is provided to reset the seconds counter. The counters' binary coded decimal (BCD) output is decoded using six BCD to 7-segment decoders and shown in a 24-hours human-readable format on LED displays.

The clock is powered using 5V power supply.

What is included

The Complete Kit includes all the components necessary to build the clock: The PCB, 16 integrated circuits, 3 dual digit 7-segment LED displays, capacitors, resistors, resistor arrays, 32768 Hz quartz crystal, and so on. The kit also includes a one meter long USB Type A to DC barrel type plug cable, that can be used to power the clock from a computer or a generic 5V USB power supply.

The Fully assembled and tested TTL Clock includes the fully assembled TTL Clock board and a one meter long USB Type A to DC barrel type plug cable, that can be used to power the clock from a computer or a generic 5V USB power supply.

Looking for PCB only option? Please check TTL Clock: PCB, Trimmer Capacitor, Quartz Crystal