jhchong

as for the transmitter part everything is ok with it.when debugging i used the function generator as a signal.

but the receiver part i got a hard time with the IR receiver....it cant receive anything data being transmit from the transmitter LED.so is there any one who can kindly help mi or give some opinion?

parts changed is:
ztx600 change to ztx300 (Darlington pair)
tsop1170 change to tsop1138 (38kHz)

Attached Images

IR circuit.JPG (31.8 KB, 55 views)

mvs sarma

Welcome to Electro-tech-online

you might have seen that TSOP1170 works at 40KHz and your modified Rx works at 38KHz
to make it operational you have to match both Tx and Rx to same frequency.

Transistor change doesn't matter so much.

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Sarma.

jhchong

but i'm not using the Tx and Rx forgot to say sorry....

cause this circuit is going to combine with PIC microcontroller not to computer.as a result,with or without it doesnt matter. is just that im unable to receive any data through the IR receiver.

IR receiver output logic is 1.and the use of the transistor is to convert it to active low signal.i added an LED to test the output at the IR module as well as the transistor...but no signal appears.

most important part is i applied a 38 kHz square wave signal to it

mvs sarma

It is not that clear.
If you did not use the PIC at all and only sent a square wave at 38KHz from some other source, what can the Rx path of com port recognize? and if you have used the PIC it was configured to output 40KHz
please try to put the schematic of what you actually wired.

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Sarma.

jhchong

hmm,maybe i try saying like this.
i'm doing a project call "infrared data transmission". my part is to build the infrared circuit, so while waiting for my partner to finish the software,me myself trying to test my circuit.my input comes from the PIC which the program has been burn inside.as a result,i do not need use the RX n TX.

i used the function generator to give a 38kHz square wave to my input which is the 2.2k resistor.and use the oscilloscope to see its output waveform for the TRANSMITTER part only.this part 100% works

next what i did is trying to combine with the RECEIVER part.as i said above the tsop is a 38kHz module rite.thats the reason y i give the input 38kHz.

now the problem comes.no signal detected at the receiver

ps:kindly correct mi if my concept is wrong thanks

mvs sarma

Basically you may have to appreciate that the content in the PIC PIC outpus is at 40KHz rate. Similarly the Rx is expected to respond at 40KHz as the driver software for reception might have been written for Getting signals from TSOP1170.
Now suddenly you replace the TSOP1170 with TSOP1738
it would not be matching the driver.

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Regards,
Sarma.

mvs sarma

experiment with a AND gate with one input 38KHz from Func GEN and other input you can supply10Hz signal to it using a 555 as astable .then try to wire a RED led on the collector path in series with the resistor.now as the Tx is on 38 and Rx you have TSOP1738,
the LED should change status when ever the 2nd pin is going high and low. this will be a crude test for checking the function of Rx
- BTW check the prog content of the PIC you will notice that the frequency is set to 40
try if you can change it to 38 then perhaps it can respond. however what is the point in changing TSOP1170-- is it non availability?

__________________
Regards,
Sarma.

jhchong

yes we have take noted that the PIC output must be 38 kHz.thanks i try it on monday when i go to lab.thanks 4 the help,appreciate it.if any questions i will post again.

Nigel Goodwin

That's unlikely to be your problem, it makes very little difference, 36KHz, 38KHz, 40KHz, all seem to work equally well with each other - you may lose a little extreme range?, but generally rooms aren't that large.

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Pommie

Why don't you use a TV remote as a test transmitter. If you see a signal from your receiver then your transmitter is at fault, otherwise it is your receiver.

Mike.

audioguru

A TSOP receiver expects to receive data, not a continuous carrier. When it receives a continuous carrier then its AGC reduces its gain because it thinks the carrier is interference from a compact fluorescent light bulb.

Look at the datasheet. It explains the AGC and shows bursts of data to keep the gain high.

The datasheet shows a graph of its bandpass. The 40kHz transmitter is only 5.3% higher than the 38kHz receiver and the tolerance is plus or minus 5% anyway. The output will typically be down to 87%. You won't notice.

Attached Images

TSOP1738.PNG (11.9 KB, 11 views)

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Uncle $crooge

jhchong

so ur meaning is?i cant use continuous signal as i mention like function generator?

audioguru

Haven't you read the datasheet? It tells you exactly how the data is supposed to be so that it avoids detecting a continuous carrier.

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Uncle $crooge

Nigel Goodwin

No, it will drastically shorten the range.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

jhchong

i think i get what u mean already.so say it in a simple way is i need to fulfill its requirements?such as duty cycle and time?

Attached Images

tsop.JPG (82.0 KB, 12 views)