QUASAR PROJECT KIT # 3148T9 - PROGRAMMABLE DOWN TIMER (UP TO 99 MIN 59 SEC)
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Pressing START turns on the output and starts the timer.
When the timer reaches zero the output turns off and the
timer resets to the preset value where it stays until START
is pressed again.
If the counter has stopped counting down in modes 3
and 5 the START and STOP buttons will function as usual
so you can start a new countdown by pressing START or
enter programming mode by pressing STOP. In modes 1,
2 & 5 you will need to use the Reset input before the
START and STOP buttons become functional again.
If power to the board is interrupted the timer will reset to
its default settings of
Mode 1
with time
00.00
.
OUTPUT
The output is a low going open collector NPN transistor
rated at 100mA. This is not much but sufficient to drive an
LED, small buzzer or relay (our 8043 and 3156 boards are
suitable).
If your load runs off 12Vdc then you could connect them
to the OUT pin marked “+” (which is actually ground in this
setup!) and the positive side of the 3148 boards power
supply.
For more information about what an open collector
output is read the notes at
quasarelectronics.co.uk/ds/opencol.txt
.
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