infrared receiver

A transmitter needs a receiver. A receiver will be described here to act as a counterpart to the infrared transmitter. Again, simplicity itself with the aid of a VFET. The infrared light which falls on the infrared photo diode (here a BPW34 type, but any other will also do) will cause the voltage across R1 to vary. This will of course affect the V F ET"s gate and the drain current, therefore, will fluctuate according to the modulation of the infrared light received. The modulation can be heard with a set of headphones. Such simplicity of course has its disadvantages. For instance, mains light bulbs which happen to be "on" in the vicinity will be heard as a humming noise. In quiet sur- roundings, however, fair reception is possible within a range of a few 5 . . . 10 V 2 infrared receiver metres, which can be extended by using lenses and other optical aids. With a few infrared LEDs and a photodiode this transmitter/receiver combination can be built very easily. It really works and i...