This infrared receiver is used with this infrared transmitter. The output signal of D1 IR diode is amplified by IC1. The diode is BPW41N works great with the transmitter and is relatively fast (~200 ns). The impulses at IC1’s output are applied to IC2 (comparator) that separate them from ambient light. Check out the infrared alarm circuit too.
The infrared received signal is decoded by a simple 2 divider, IC3a. Each impulse produces a change of the state at the stage output. The output signal is filtered with R7-C11 and decoupled with C12, resulting in an audio signal suitable for control of high impedance headphones.
The output signal of the infrared receiver can be improved with the help of an order 3 active low-pass filter (cut freq at 10 – 12 kHz) that will serve as buffer stage too. With the receiver placed at 1 meter distance from the transmitter and 30% modulation, the signal to noise ratio is -50 dB. The maximum working distance without interferences was around 5 meters. The IR receiver circuit absorbs a current around 15 mA, this makes it advisable to use a rechargeable battery (NiCd).
sent by Nichol Iarin, Norway.