digital input to infrared modulator and demodulator

Thread Starter

denison

Joined Oct 13, 2018
233
att Mr Crutschow. I am building an infrared emitter and detection circuit with frequency of 38khz. This is an extension of my previous circuit with
a frequency of 10k and 1k modulating sine waves.
In this the 38khz is a sine and the modulating signal is a digital or pulse input. I have the ky-005 emission module and ky-022 receiver and I believe this is how they work. I know that the output of the ky-022 is digital.
In my previous circuit I also added a passive filter of 15k and .01uf to cancel out the high frequency component (this I did not show). Anyway the result was good. With the infrared circuit everything is good up to the filter stage where the output is a very poor reproduction of the pulse input. I am sure this would not be the case with the real thing.
Using the ky-022 ir receiver with my tv remote I get a very strong light from the receiver led to show it receives the 38khz signal. However using the ky-005 the led response is very faint. I need a much more powerful emitter. I see on e-bay that there are 3 watt emitters. These are all from China and the U.S. Anybody know of an Australian source for these more powerful emitters? There are long wait periods for stuff from these sources.
 

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BobTPH

Joined Jun 5, 2013
3,658
There is something very wrong if you need a 3W transmitter, unless you are trying to go 100m in full sunlight.

I made a 38KHz IR remote using a TSOP receiver and a 50 mA LED. That is at about 1.2V, so maybe 60mW.

You could point it anywhere in the room, and the receiver would pick it up. I practically had to cup my hand around the sender to make it fail.

It also worked fine at 1 m in sunlight, which was what I needed since this was an outdoor alarm system.

Bob
 

Thread Starter

denison

Joined Oct 13, 2018
233
There is something very wrong if you need a 3W transmitter, unless you are trying to go 100m in full sunlight.

I made a 38KHz IR remote using a TSOP receiver and a 50 mA LED. That is at about 1.2V, so maybe 60mW.

You could point it anywhere in the room, and the receiver would pick it up. I practically had to cup my hand around the sender to make it fail.

It also worked fine at 1 m in sunlight, which was what I needed since this was an outdoor alarm system.

Bob
Hi Bob, Sounds good. Could you send me a schematic of your circuit with resistor values and parts required etc. That would be great. thanks
I believe now that my receiver may be crap. Its a ky-022 ir receiver. The receiver has an led which flashes brightly when I use my tv remote. But when using the ky-005 emitter the flash is very faint.
 

sghioto

Joined Dec 31, 2017
2,394
I believe now that my receiver may be crap. Its a ky-022 ir receiver.
If it receives the TV signal OK then the module is fine. I suspect your modulation on the KY-005 is the problem. I've never heard of modulating using a sine wave. The KY-005 is designed for serial data which is digital.
 

Audioguru again

Joined Oct 21, 2019
3,516
The datasheet for a TSOP IR detector IC shows that is sensitivity is reduced when it receives sunlight or the continuous 38kHz from a compact fluorescent light bulb. The 38kHz must be in specified bursts with specified gaps between the bursts for good sensitivity. The bursts and gaps are the data sent by an IR remote.
 
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