10 OUTPUT LED SEQUENCER
Here is 10 output LED sequencer. After the last LED is illuminated, the circuit is reset.
This circuit is build around readily available, low cost components - a 555 and decade counter CD4O1 7.
The timer IC NE555 is wired as an astable multivibrator that produces 6Hz clock at its output pin 3.
The 4017 is a CMOS decade counter with 10 outputs. Inputs include a CLOCK (Pin 1 4), a RESET (Pin 15), and a CLOCK INHIBIT (Pin 13).
The clock input connects to a Schmitt trigger for pulse shaping and allows slow clock rise and fall times (not needed in our case).
The counter advances one output at the rising edge of the clock signal if the CLOCK INHIBIT line is low. A high RESET signal resets the counter to the zero output.
The circuit may be configured for counts less than 10 by connecting RESET to an output pin (one after the desired count).
Thus, a five stage sequencer can be made by connecting pin 15 to pin 1.
A CARRY-OUT signal (pin 12) can be used to clock subsequent stages in a multi-device counting chain.
The output from 1C2 pin 3 is connected to clock pin (pin 14) of the IC3 for sequencing operations.
NPN transistors Q1- Q10 are used to increase the output current for the LEDs which is set by the common 150 ohm resistor. In the circuit, only one of the outputs is HIGH at any one time and the output advances by one count with every clock pulse.
