Infrared Receiver

I'm using a VS1838 infrared receiver (link) to receive signals from an LG TV remote control. Everything works perfectly, but from 3-4 meters the remote control must be pointed almost straight to the receiver, otherwise it does not receive correctly the values of each button.

The same remote control with the TV instead has no problem, I can almost point at 90 degrees from the TV in any direction and is correctly received.

At this point I deduce that is a receiver problem. Could I amplify the received signal or exist a best infrared receiver?

There are no standards for IR remotes.

It may be that the transmitter uses a different carrier frequency than the VS1838 infrared receiver (38 kHz). An oscilloscope and an IR photodiode would help isolate the problem.

It is also possible that the TV remote uses a different IR band than the receiver is on.

It is also possible that you have not got the recommended decoupling resistor and capacitor mentioned in the data sheet fitted. That reduces the range as well.

Grumpy_Mike:
It is also possible that the TV remote uses a different IR band than the receiver is on.

It is also possible that you have not got the recommended decoupling resistor and capacitor mentioned in the data sheet fitted. That reduces the range as well.

Did you mean this circuit?

But there are 3 things not too much clear:

  1. What is ?
  2. Are 100 Ohm ?
  3. What is this? Arduino?

PS There is another way to get the right band of remote without an oscilloscope?

I'm sorry for my newbie questions? :sweat_smile:

Did you mean this circuit?

Yes.

  1. What is ?

A 100nF or 0.1uF ceramic capacitor.

  1. Are 100 Ohm ?

Yes

  1. What is this? Arduino?

Yes

PS There is another way to get the right band of remote without an oscilloscope?

No you don't GET the right band with an oscilloscope, you look to see if your modulation frequency is correct with an oscilloscope.

The only way I know of testing the band of the emitter is with a spectrometer. The only way of finding the band of the receiver is by looking at the data sheet.

Thanks! Now seem that the problem is solved. Moreover i noticed that IR receiver works better if infrared rays coming from side and not from front. Like the image below, the rays come as the red arrows.

Then the circuit is helpful to reduce noise right?

hen the circuit is helpful to reduce noise right?

Yes. It is the power supply noise that looks like a signal to the decoder chip and the signal has to be bigger to drown out the noise. As we are only dealing with tiny signals it only takes a tiny amount of noise to disrupt it. The technical name for this is signal to noise ratio.

If you notice the case of the receiver you will see a metal band in front of the sensor. I guess that it is acting as both a bit of a block to direct waves and is reflecting waves that come in from the side.

Grumpy_Mike:
If you notice the case of the receiver you will see a metal band in front of the sensor. I guess that it is acting as both a bit of a block to direct waves and is reflecting waves that come in from the side.

If i remove this metal bands, the signal will be received better? Are these bands really useful?
All the metal case is connected to gnd

By the way, seem that the TSOP1738 have a better receiving angle and distance of my VS1838. Is correct? Maybe i can replace with this IR receiver to increase performance.

If i remove this metal bands, the signal will be received better?

No idea, you could try it.

the TSOP1738 have a better receiving angle and distance of my VS1838.

You can not say that from those figures because the TSOP states the test conditions of the IR diode sending the date where as the VS does not.

If i remove this metal bands, the signal will be received better? Are these bands really useful?

The metal bands (cross) are there to help protect against electrostatic fields and discharges, as there is very sensitive circuitry under the plastic.

Removing the bands will probably not improve the signal.

Ok now all is working well, thanks to all! :wink: