555 Infrared Transmitter-Receiver
Infrared transmitter and receiver circuit shown in the schematic
diagram below can be used as remote control. The transmitter is
basically an oscillator circuit, and the frequency can be adjusted using
R1 potentiometer (or trimmer pot). This oscillation makes sure if the
signal can be distinguished from other source by the receiver.
The
receiver is actually a bandpass filter which filter out noise signal.
The frequency of this filter is determined by L and C in the feedback
path (from output to inverting input of the op-amp). D1 is inserted in
the feedback path to enable rectifying very small signal, since the
op-amp feedback mechanism will compensate the forward drop voltage of
the diode. The last op-amp is employed as a comparator, with the
threshold is adjustable via R3
potentiometer. The op-amp should be supplied with + and – 12Volt, and
the R3 potentiometer should be supplied with -12V. [Circuit's schematic diagram source: hobbyprojects.com]
