infra-red headphones: receiver - for unhampered listening pleasure

for unhampered listening pleasure This circuit is the receiver to match the transmitter published elsewhere in this issue. Together these two form a very simple, but none the less effective, wireless headphone, or a transmission system for any audio signal. The signal is transmitted by the infra- red LED in the transmitter. When the receiver reconverts this IR signal into electrical pulses, it will be a rec- tangular waveform in which the width of the pulses corresponds to the audio information. The signal ob- tained after amplification and filtering only has to be integrated in order to retreive the audio information. What could be simpler? The SL 486 IC is a suitable single- chip receiver for our wireless head- phone system as it contains, among other things, a regulated amplifier o ft) DI BP 104 "Cl SL 486 ce 3 7 , C11 0 100 m 10 V 4p7 474 1011 10V 14 R2 9 V • C) = 25 mA and a filter section. The signal picked up by the infra-red photodiode (such as a BP 104) is fed to the in...