Saturday, May 17, 2008


This is a simple yet effective IR proximity sensor built around the TSOP 1738 module. The TSOP module is commonly found at the receiving end of an IR remote control system; e.g., in TVs, CD players etc. These modules require the incoming data to be modulated at a particular frequency and would ignore any other IR signals. It is also immune to ambient IR light, so one can easily use these sensors outdoors or under heavily lit conditions.
Such modules are available for different carrier frequencies from 32 kHz to 42 kHz.They cost some thing around 20Rs.
In this particular proximity sensor, we will be generating a constant stream of square wave signal using IC555 centered at 38 kHz and would use it to drive an IR led. So whenever this signal bounces off the obstacles, the receiver would detect it and change its output. Since the TSOP 1738 module works in the active-low configuration, its output would normally remain high and would go low when it detects the signal (the obstacle).

In the reciving part instead of using IC555 u can use the time from u r muc.


balaji said...

pls tell me whr to give the output of the sensor....should it directly be given to mu c?


The output turns to low when an Obstacle is detected........ It can be directly given to the uC pin or via a transistor to boost the current..........

Faizy said...

You can directly pin to uc, but do check that the current you are getting is atleast greater than 10ma. If its not greater then 10ma then there would be difficulty detecting for the uc. Do check for current drops in your circuit, if you are getting very low current. Are you plugging in with a battery, wat are the specs of it ??

circuit_freak said...

does this circuit works with tsop 1838.........??