Electrons: Building a cheap AT89C2051 clock kit

One of the things I haven’t yet experimented with was a numeric digit display. Whilst I was looking for one of these, I came across a kit of parts to make up a clock which included one, for £1.68. It took a while to arrive, but it was relatively fun to make.

The eBay listing was:
"4 Bits Digital AT89C2051 Electronic Clock Clocks Production Suit DIY Kits New"

The kit has a socketed Atmel AT89C2051 which I thought would be a custom clock chip - but it turns out that it's just a micro controller so I could, if I wanted, program it to do something else - or at least clone the program from it to make another one.

Other parts of note are a 12mhz crystal - which the controller uses to keep its time, a speaker, and a resistor network - so that with one component, you can put in the resistors for all of the LED for the segments at once.

Unfortunately, in this kit, one of the little switches was missing - so I can only part-build it. Looking at the back, I could just wire in any switch for the second one - as it's just joining two tracks - but I’ll wait 'til I get some of these little switches and put the proper one in. I’m not going to complain to the seller about this - just one of those things.

The kit took around 25 minutes to build - but that included looking for some red and black hookup wire to power it with. Had the second switch been supplied, I may have taken around the same time. Here is a short time-lapse of the build:

You’ll see towards the end that pushing Switch 1 makes the thing beep - then a minute later it beeps a lot, some kind of alarm - but I don’t particularly know how to program it yet. I’ll have to wait 'til I get the second switch and experiment.

I want a mini-clock somewhere in my workshop - and this takes 3-6v - so I may try to usb-power it at some point and add it to a usb strip.

As these little kits are so cheap, I may do some more of these short build videos. This one was easy to demonstrate at the end, since it's pretty much self-contained - others may vary.

7-Jan-2015 Add comment