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The heart of the circuit is
IC555. The main component of the circuit is only IC555.
Connections:
Both ICs are connected in astable mode. The
frequency of U2 is 0.5 Hz and U1 is 38 KHz. This is
decided by RC components connected with it. The output of
U2 is connected with reset pin (4) of U1. Thus the output
of U2 controls the operation of U1 means it will switch on
or off the output of U1. The output of U1 is fed to two IR
LEDs through Darlington pair made up of Q1, Q2 and R5. The
9V DC battery is connected with circuit through SPDT
switch SW1 as shown.
Operation:
As shown in figure when SW1 is in position as shown
the transmitter is On and also the red LED is also ON.
When switch changes its position the red LED and
transmitter is off and only green LED will on. When the
circuit is energized U2 will start generating high pulse
at every 1 sec. as this pulse is fed to reset pin of U1 it
will generate 38 KHz square wave and give it to IR leds.
IR leds will generate IR beam of 38 KHz for the same time.
Thus after every one second the IR beam of 38 KHz is
generated for one second only. This cycle repeats till the
red light is on.
Note:
The range of this transmitter is limited to 10 ft only.
89C51
based IR receiver for Engine:
The
IR receiver circuit housed in engine is as shown below.
The main components of the circuit are IR sensor TSOP
1738, microcontroller 89C51, current driver chip ULN2003A
and all voltage regulator ICs (78XX series).
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