Bi-Color Dancing Light
LED (Light Emitting Diode) is a semiconductor. We know that
the diode allows the current in one direction and does not allow the reverse
current which will affect the components in circuit. LED also does the same
function but will emit light when it allows the current. There are lots of
application of LED in electronic devices.
The circuit diagram is given below
- The circuit consists of IC-555 timer, resisters, capacitor,
POT and LED's.
- Here
timer is used for setting the sequential flow rate for the LED's
1st and 8th pins of 555 timer are used to provide power,
Vcc, and GND respectively.4th is the Reset pin which is an active low input and
is tide to Vcc to avoid accidental resets.5th is the control voltage pin which
is not used in this application.
LED ON-OFF period is determined by varying POT resistors and
the capacitor.
We can determine the time period theoretically by the
equation
T=1.1RC
And this R depends upon the POT resistance (i.e. Variable
Resistance)
When the output is LOW(0v) upper LED glows and when the
output is HIGH(5V) lower LED glows. You can use higher supply voltages if you
need to drive more LED. You can use higher supply voltages if you need to drive
more LEDs. LM/NE555 can work upto 16V (i.e. Vcc) and SE555 can work upto 18V (i.e.
Vcc). 555 can source or sink upto 200mA current, if you need more current use a
transistor driver. You can also connect this circuit to relay for controlling
incandescent lamps as shown below.
Here transistor acts as switch, when the base input is HIGH transistor turns on and the relay energized. Since the output of the 555 is square wave, the relay energizes and de-energizes continuously. Incandescent lamp turns ON alternatively since there are connected to normal open (NO) and normally close(NC) of the relay output.
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