The 555 timer can only provide short
and poor accuracy timing periods.
The ZN1034 can provide timing periods up to several days with great
accuracy.
The timer contains an oscillator, the
frequency of which is controlled by an external resistor and capacitor.
The output of this oscillator goes into
a 12 stage binary counter.
The output of the counter changes after
4095 cycles of the oscillator.
The timer require a 5 volt supply and
consumes 5 mA.
The timing cycle is triggered by
a negative going edge to pin 1.
Pin 3 goes high during the timing
period. Pin 2 goes low.
The timing period is determined by
t = CR,
where t is in seconds, C is in Farads and R is in ohms.
The following table gives values for
various timings
1 second
10 nF 39k
1 minute 100 nF
220k
5 minutes 1 uF
100k
1 hour 1 uF
1.2 M
1 day 10
uF 3.3 M
1 week 100uF
2.2 M
Use low leakage capacitors, such as
tantalums, for high values of C.
Use values of C between 3.3 nF and 1000uF.
Use values of R between 5k and 5 M
The timing period can be adjusted to a
more precise value by a trimming potentiometer between pins 13 and 14.
The timer can use voltage
supplies other than 5 volts if a resistor is connected between pins 4
and 5 and the supply rail, as shown in the next diagram. A decoupling
capacitor is necessary.
Calculate the value of the resistor from
R = supply voltage - 5V/ load current in mA. ( the ZN1034 can supply
output current up to 25 mA).
The timer can provide high power
control by driving a transistor which in turn drives a relay.
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