IR sensor module gives low pulse which goes high quickly

[shaz]

ir sensor pulse low

dear frndz,

i am designing this ir sensor module..the circuit daigram is as shown below..now when i test this ,the ir sensor gives output signal ie., a low pulse for less than one second and then goes high . i am giving frequency output of oscilltor as 38khz.
please help me find out the mistake

 

[barbar]

Re: ir sensor pulse low

As I see with the Vishey device they has protect mechanizem against fulse signal. One of its feature is that it agnore continuse signal even if it 38Khz, if it don't have off times. As I see you don't has it with you 555 so maybe that the problem.

 

[shaz]

ir sensor pulse low

sorry but i could not understand what u r trying to say...what should i do then

 

[Borber]

Re: ir sensor pulse low

Vishay receiver blocks too long pulse chain. Transmitted signal must be in form of bursts so there must be pause interval between bursts. This is made for better interference immunity. Simply download datasheet for your Vishay receiver. There you will find detailed explanation.

 

[skydiverc]

Re: ir sensor pulse low

What Borber is saying is that the receiver is set to ignore a constant signal.
The data sheet states that the device needs to see a "Burst" not a constant signal.
Basically modify your circuit so that when you press a button the 555 starts oscillating.
You can do this by placing a resistor between ground and pin 4 say 10K.
Then put a SPST switch to V+ to pin 4, 10K junction.
Since pin 4 is the reset pin when it is low the 555 is off.
Press switch, applies V+ to pin 4 turning on 555.
This way when you press the switch the relay should de-energise as long as switch is held or as long as the device thinks it has a valid signal.
Good luck