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C51 4 Bits Electronic Clock kit

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ledtester:
About 12 maybe more years ago I bought this timer kit which used a AT89C2051:



They sold each function as a separate pre-programmed chip -- e.g. clock, stop watch, event counter, frequency counter, etc.

Note that the crystal is hidden under the IC socket. The assembly instructions said to split the socket at its ends so you could spread the two halves enough to make room for the crystal.

No buzzer, but all of the important signals are brought out via a header. The seven-segment digits have transistor drivers.

Found the original docs and schematic. The docs suggest the kit was available from at least 2002.

ledtester:

--- Quote from: aldolo on January 09, 2021, 07:35:36 am ---have you got the instructions around? i don't recall at all how to setup the various functions. tnx

--- End quote ---

From the Q&A section on an Amazon page and jumping through a few links I ended up at:

https://attach01.oss-us-west-1.aliyuncs.com/IC/DIY-Manual/1765.pdf

Found via IC Station's sitemap:

http://www.icstation.com/sitemap
http://www.icstation.com/product_document/Download/1756.pdf


aldolo:
i've found also the instruction of another of my clocks. but in chinese.... thanks to google i've got now the translation

https://github.com/aldolo69/AT89C2051_4_digit_clock

edy:
I bought one of those cheap clock kits off eBay, soldered it and the thing never worked. It was fun soldering practice yes, I double and triple-checked all of the connections and components. A bunch of trannies seemed to be mislabelled or the wrong ones were provided (PNP vs NPN) but I was never able to figure out why it was dead when fully assembled. For $5 shipping in, it was not worth wasting more time on it. Now I have a bunch of components.

Careful not to leave these around attached to brown cylinders these days, one is liable to scare people:  :-DD

WattsThat:
Those clocks are yeah, well, okay for soldering practice. Also good for learning 8051 core processors if you’re so inclined but you’ll need an external programmer like the TL866II or similar.

The Chinese 1 inch, 4 digit clocks that use the STC 8051 core processors are actually usable and only need a serial port to programmer. Alternative source code is available on github, here is my contribution:

https://github.com/aFewBits/stc-led-clock

There are other versions available as well, there is another version more popular than mine. No idea why  :palm:

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