View Full Version : How to get the output from TSOP ??

10-01-2008, 11:33 PM
I have built an IR detector using two 555 timers and TSOP 1738.Now the problem is that I have given a bursts as per the datasheet and the TSOP is also working accordingly.

So when I bring any obstacle TSOP gets the reflected IR and starts giving LOW and HIGH output at a very high rate.Its not constant,so how can i get the data back to my PC through RF module?

Will the rf module work on the output which is getting high and low rapidly?

10-02-2008, 07:53 AM
RF modules are AC coupled.
It simply means you CANNOT have a DC component, you should always have change in the input.

So, when your obstacle sensor does not detect an obstacle, the input to the RF module will be a DC high, which will be received by the receiver as "beautiful" noise.

So, you cannot simply connect the output of TSOP to the RF module and expect it to work. Alternatively, you can connect the output of the sensor to a monostable and then to some encoder before the RF module.

just out of curiosity, why do you want to make the obstacle sensor module wireless?

10-02-2008, 01:44 PM
well i want to have the detection wireless because it will be mounted on my R/C car which will be controlled through computer.So i dont want to have any sort of limitation in the movement bcoz of those wires.

Also u righty said i can't connect the o/p of TSOP directly to the data pin of RF Tx...here i will be using the HT-12E i think....then it will work.

But my question is that will the RF-Tx be able to transmit the signal which is changing so rapidly or do i need a steady LOW or HIGH and not a fluctuating one ?

10-02-2008, 03:25 PM
What you need is data sheet to know the switching speed of holtek ic's, as of now just experiment, but a monostable idea seems good, because a monostable will be triggered and you can set the output pulse width according to your requirement

10-06-2008, 07:26 PM

As allbits said RF modules are AC coupled. They cannot be used to send constant high or low of long length. You must first try to get up each part first then asseble them. Like separatly test RF modules TSOP and your transmitter (NE555+ IR LEDs).