The LM567, NE567 and SE567 are general purpose tone decoders designed to provide a saturated transistor switch to ground when an input signal is present within the passband. The circuit consists of an ...

This infrared transmitter use PWM (pulse width modulation). The transmitter is equiped with LM567, tone decoder circuit. Audio signal ( at least 50mVvv ) is amplified with T1 and then it is used to ...