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Friday, April 12, 2013

4017 LED Knight Rider Running Light Circuit Diagram


In this  4017 Knight Rider circuit, the 555 timer is
wired as an oscillator. It can be adjusted to give the desired speed
for the display. The output of the 555 is directly connected to the
input of a Johnson Counter (CD 4017).
 The
input of the counter is called the CLOCK line. The 10 outputs become
active, one at a time, on the rising edge of the waveform from the 555.
Each output can deliver about 20mA but a LED should not be connected to
the output without a current-limiting resistor (220Ω in the circuit above).

The
first 6 outputs of the chip are connected directly to the 6 LEDs and
these “move” across the display. The next 4 outputs move the effect in
the opposite direction and the cycle repeats. The animation above shows
how the effect appears on the display. Using six LEDs,
the display can be placed in the front of a model car to give a very
realistic effect. The outputs can be taken to driver transistors to
produce a larger version of the display.


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