Timer Module Kit  (280-4032)         Features         Faxback Doc. # 14147

Your Timer Module Kit uses the popular 555 integrated circuit (IC).  You
can set the timer to turn on a device which uses less than 300 watts after
a delay period between 1 and 1000 seconds.

The resistor and capacitor you select determine the timing interval.  The
discharge pin (Pin 7) initially keeps the capacitor discharged.  This
causes the output pin (Pin 3) to stay at zero volts, keeping the relay
off.  When you press the switch (SW), the output pin "goes high" and the
relay turns on.  At the same time, the short across the capacitor is
removed and the capacitor begins charging slowly through the resistor.
The threshold pin (Pin 6) monitors the voltage across the capacitor as it
slowly rises.  When the voltage across the capacitor exceeds the voltage
at the control voltage pin (Pin 5), the discharge pin shorts the capacitor
to ground, discharging the voltage in the capacitor.  The output pin goes
to zero volts at the same time, shutting off the relay.

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