We are making this sensor to use as the front sensor to detect obstructions. Until now we have designed the transmitter part of the sensor.
In the power supply unit 230V, 50 Hz AC mains is stepped down by transformer X1 to deliver a secondary output of 9V, 500 mA. The transformer output is rectified by a full wave rectifier compromising diodes D1 through D4, filtered by capacitor C1 and regulated by IC7805 (IC5).Capacitor C2 bypasses ripples present in the regulated supply.
The transmitter section is built around timer 555 (IC 2), NPN transistor BC548, infra-red LED1 and some discrete components. Timer NE555 is wired in astable multivibrator mode to generate pulses of 38 KHz frequency by adjusting preset VR1. Transistor T1 is used to drive IR LED1, which transmits modulated IR signals up to a few metres.
IR Tx and Rx