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The LED sequencer circuit uses the 555 timer to produce the clock pulses required for CD4017, which is operated in Astable mode. Primarily it is important to remember that, as the CD4017 is a CMOS device, it is very sensitive to the static electricity. This circuit is also called as “LED chaser circuit”. The LED sequencer circuit by using CD4017 and IC 555 is shown below. Application of CD4017 LED Sequencer using 4017 Let us see some examples in which CD4017 is used. Next this output is shifted to its next output pin and this sequence continues till the next clock cycle. Then the output of the first output pin 3 will be high. If we observe that, before applying the clock signal, the RESET is set to High, so the reset pin input sets all the output to their initial state. This is the timing diagram of the CD4017 with, shows us the comparison and also explains the counting sequence of the outputs, shifting from one pin to its next. Counting operation of CD4017 using waveforms
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This is used to ‘ripple’ the IC, which means to delay in counting operations.
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It completes one full cycle for every 10 clock cycles. The pin 12 is supplied with the CARRY OUT signal. Pin number 8 acts as ground and it must be connected to negative supply voltage & pin number 16 is the supply pin for CD4017 and it is connected to positive voltage supply. Reset pin should be connected to ground in order to reset the circuit.Reset pin resets the output of the sequence.That is the current state of the output sequence is set to initial state.The clock input pin (pin number 14) responds only to the positive voltage signal or positive clock.It is not left unconnected as per the CMOS input standard rules.The important thing to remember is, if we don’t connect any clock signal to this input pin, it must be connected to either positive or negative voltage supply.When the first clock pulse is detected pin 3 goes ,for next clock pulse pin2 goes high,like this sequence is formed.Clock signal provided to 14 th is responsible for sequential output.In order to disable or switch off the IC,this pin should be connected to active high input.When this pin is active high ,it ignores the clock signals.Enable pin enables the CD4017 IC.IC is enabled when the pin is active low.For each clock signal each pin goes high in a sequence. These pins changes to ‘high’ level one by one (one after another) in a sequence.Pins 1 to 7 and 9 to 11 are outputs pins.Output pins of CD4017(Pin 1 to 7 & 9 to 11) This IC is also used in electronic industries, automotive industries, manufacturing medical electronic devices, alarms and in electronic instrumentation devices. The clock speed or operational speed of CD4017 IC is 5 MHz.It is compatible with TTL (Transistor -Transistor Logic).The supply voltage of this IC is 3V to 15V.Counting operation of CD4017 using waveforms.
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Ground pin & supply pin(Pin 8 & Pin 16).Output pins of CD4017(Pin 1 to 7 & 9 to 11).