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The 1970’s was a great time for hobbyist. This was a time before everyone had home computers, radio controlled toys, home automation
gadgets, microwave ovens, cell-phones.
I, like other hobbyist, was tinkering around building what now seems like very simple
stuff. Voice controlled cassette tape switch, electronic dice displaying on a 7 segment display, a relay controlled by a flashlight,…
simple stuff that taught the basics of electronics, logic, and control systems.
One circuit I designed myself and gave to my
father for Christmas was a digital clock made with TTL, using the 74LS83 4 bit adder to produce the hours digit. At that time,
I did a poor job of filtering the 60Hz, so the clock kept gaining time due to line noise, and it soon moved to the back of his closet.
I
have re-created that circuit, this time with great filtering, and now offer it to like minded hobbyist.
The manual (above right)
describes the circuit functionality along with full instructions for building it. You can buy the PC board only, or I recommend
buying the whole kit with all parts solder and desolder braid. A wood plaque is available separately.
This clock depends upon the 60Hz mains supply, and no conversion instructions exist for 50Hz. An IC change and cuts and jumpers would be needed.