Saturday, 25 June 2011


A decade counter is simply a device which counts from one to ten.A decade counter here is made by using a common LM555 timer ic and a CD4017 decade counter ic.The main pupose of using an 555 timer here is to provide pulse signals to the input of the ic CD4017 to toggle from one value to another.With each pulse the counter get increased bye one.The timer value can be set by changing the value of the resistor r1 and r2 and also the capacitor c1.Here i am using resistor value of 28kohm each and a capacitor value of 100uf.the 555 timer is working in astable vibrating mode which i will discuss later.When the power is supplied to the LM555ic the pulses starts entering into the port 14 of CD4017 counter.This starts the counting of the counter.The counter counts from 1 to 10 and then again return to 1 and this process continues till the pulses are fed into the input of 4017 ic.The final project can be viewed on youtube.Here in this video,i have set the counter to count from one to four but it can be extended to a value of ten.

The number of seven segments required for this decade counter is obviosly ten.The connection of a seven segment will we shown later in this forum.

The capacitor having value 0.01uF is just an ordinary ceramic capacitor which can be easily digged out of spare circuits having printed 103 on them.The capacitor c1 is an electrolytic capacitor having value 100uF.The resistance value can be changed to get the desired pulse timings.For any queries ,please post here.

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