Construct a simple electronic project - Cascaded Timer using 4528 IC

Simple Electronic Project - Cascaded Timer using 4528 CMOS IC

This is a simple electronic project that uses a CMOS dual retriggerable monostable IC 4528 in a cascade timer circuit. The typical features of the CD4528BC IC which is also manufactured by Fairchild Semiconductor is as below:

a) Wide supply voltage range: 3.0V DC to 18V DC.
b) Separate reset available.
c) Quiescent current = 5.0 nA/package (typ.) at 5.0 V DC.
d) Diode protection on all inputs.
e) Triggerable from leading or trailing edge pulse.
f) Capable of driving two low-power TTL loads or one lowpower Schottky TTL load over the rated temperature range.
g) Operating temperature from -40 Celcius to +85 Celcius.

The graph below shows the pulse width versus the capacitance Cx used for the various power supply and resistance Rx used.

Figure below shows how the CMOS timer can be easily cascaded with other similar 4528 circuits to lengthen the timing needed. The timing of the project is determine by VR3 and C1 for the first stage and VR4 and C2 for the second stage.

Once button S1 is pressed , the 1st stage output pin 6 logic level will go high and output pin 7 will go low for the preset time which is determined by VR3 and C1. When the time is up, the output pin 6 will go low and pin 7 high. At this moment of time, pin 7 will positive trigger the 2nd stage of the timer at pin 12. Output pin 10 will go high and pin 9 will go low for a time determine by VR4 and C2 before the cycle end with pin 10 back to low and pin 9 to high.

By having a few of these IC, this circuit can be used as a simple timer project to trigger a relay after a certain time has elapsed or any other application that one may think of.

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