4-Digit Digital Clock Kit
(DC 4.5 - 6 V)
Digital clocks used to be built around customized LSI
ICs. These ICs are gradually replaced by low-cost
, programmable MCUs which are readily available & easy to program. This simple digital clock is based on a
AT89C2051 micro controller. It uses a quad 7-segment LED displays to show the time of day (HOURS & MIN) .
Micro controller (MCU) allows very accurate timekeeping and for this kit in particular, the error is less than a few
seconds per month.
Power supply : The kit can be powered by any 4.5 ~ 6V battery or dc supply.
For testing purpose, 3 AA batteries can be used but they can only keep the clock running for a few days because the
display consumes quite a lot of power. DC adaptor is more practical if the clock were to be used over long period
of time. DO NOT CONNECT THE KIT TO DC SUPPLY HIGHER THAN 6V AS THIS WILL CAUSE PERMANENT DAMAGE
TO THE IC.
Setting the time : After the kit is completely assembled, insert 3 pcs of size AA batteries to the battery holder and then
press the RST button (S1) once to set the kit to a proper start. Then press the HR button (S2) and MIN button (S3) to
set the current hour & minute ( a blinking colon indicates that the clock is in normal operating mode )
| 3 x size AA batteries holder included
(3 x 1.5V= 4.5V)