Full clock kit build and setting guide.

Описание: Another of the many eBay clock kits. This one is supposed to have a timekeeping issue which I wanted to investigate. It's a fairly easy kit to build, but would really be best done with a fine tip soldering iron and good quality 60/40 tin/lead solder with a flux core bought from a good local supplier. (not eBay).

Note that the timekeeping on this clock is terrible. Probably due to poor decoupling and layout causing induced noise on the RTC (Real Time Clock) circuitry when the unit is powered.

The resistors are all 10K so nothing to do with display current limiting. It seems to rely on the output impedance of the microcontroller for that. Without metering them out I'll make a guess that they are for pull up/down for the button inputs, RTC data/clock lines, transistor base and probably part of the thermistor bridge.

To program, hold the left button until the display shows Time. Use the right button to step through options, the left button to select one, the right button to increment and finally the left button to exit the settings.
Time - set time.
Dat - set date.
Alar - toggle alarm on and off, and set alarm time.
Font - select display font.
Disp - choose display style (option 5 is just time).
Midp - select style of flashing centre colon.
Fmt - Format 24-hour or 12-hour.
Brh - Birthday reminder option.
Brig - Set brightness of display.

To toggle between celcius and farenheit click the right button while the temperature is displayed.
I've not found a calibration option for the thermistor yet.

If I sound a bit odd it's because I was loaded with the cold when I filmed this. It always happens with seasonal transitions.

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