Designed and hand made in Canada, it is a software-based emulator of the exact functions of the Mostek MK5017AA clock chip used in many Heathkit digital clocks, including identical response of the time setting buttons and alarm tone. Just unplug your old chip and plug this in, and you're up and running!

I made this after buying a non-functional $5 Heathkit clock at a Hamfest, thinking it just needed minor repairs. Unfortunately, the main chip was blown out. Checking the forums, I found many people said "couldn't you just make a microcontroller based replacement?". Sure, but nobody had done it. I liked the clock, and the expensive neon gas discharge displays were in good condition, so I set about designing and building one. I figured there would be others who wanted to resurrect their broken Heathkit clock.

What makes it special is that the MK5017AA chips have not been produced since the early 70s. So if your chip is blown out, your clock is useless. The genuine chips sold for $15 back in 1972, which is $116 in today's dollars. So...this is even cheaper than the original.

This works for clocks with LED, fluorescent, or gas discharge displays. Round gold-plated pins similar in size to the original chip provide excellent contact. A quality 24-pin milled pin socket is provided to replace the poor quality socket pins in most Heathkit clocks. And best of all, the hardware design and software are all open source, so you can modify things like the alarm tone.

Like the original, you can select 50Hz/60Hz operation, and 12- or 24-hour operation using the jumper options built into your clock. Time is kept just like the original, from the line frequency. A crystal oscillator provides a clock source for the ATMEGA328PB microcontroller, and sets the display scan frequency. The scan frequency has been optimized for gas discharge displays, which are the most sensitive. But it will work well with fluorescent and LED displays. Level translators convert between the 15V that the original MK5017AA chip used and the 5V required by the microcontroller.

These are fully built, tested, and get a 12-hour burn-in to identify any issues before shipment.

Kits will be sold in the future. This board version had too many super-tiny components to reliably offer as kits. Please message me for details on when the kits will be available. The kit will come with a soldered-down, pre-programmed microcontroller, crystal, and regulator already installed.

FREE SHIPPING to Canada. US shipping includes $29 per board tariff fee. Sorry, I can't control that.

NOTE: This chip works in the GC-1005 and GC-1094 Heathkit clocks only. Please verify your clock uses the MK5017AA chip before ordering.