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I was trying to get a IR signal from a remote controller.

I hooked the IR receiver to the oscilloscope and I got nothing. Then I brought the remote controller very close (~1 mm from the receiver) and I started getting a signal, but it was random (with another controller that I have, if I hold one button, it first sends the button code and then a constant value; this doesn't happen with the other controller).

I disassembled the controller; this is all the information I got:

  • XWDB-1106
  • LXZK-TX1021-v1.0
  • (cristal oscillator) NDR4208 (I think it ends with "i1", I'm not sure)

The receiver I'm using is the VS1838B.

Schematic

Maybe the controller's frequency is not the same as the receiver's?

Edit: The remote controller was RF, not IR.

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    \$\begingroup\$ 1) include links to datasheets 2) include a schematic of your setup (yes even when it is "obvious"). On this site we like schematics so include one. \$\endgroup\$
    – Bimpelrekkie
    Commented Dec 9, 2020 at 15:35
  • \$\begingroup\$ What voltage supply did you power the VS1838B with? \$\endgroup\$
    – Andy aka
    Commented Dec 9, 2020 at 15:37
  • \$\begingroup\$ Some receivers need a pull-up resistor. Try another remote, you can check them with a camera with poor IR filtering, eg webcam, most non-apple phones, etc. \$\endgroup\$
    – Chris Stratton
    Commented Dec 9, 2020 at 15:40
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    \$\begingroup\$ Most likely you have connected the VS1838B wrong. Show how you connected it and we can check. \$\endgroup\$
    – Justme
    Commented Dec 9, 2020 at 15:46
  • \$\begingroup\$ I've added a datasheet (all I found was in chinese) and the schematic. Beside the 100uF capacitor (which I think it's a lot, but it's what the datasheet says) I don't think I have anything connected wrong. Also, have in mind that the circuit works with another controller. \$\endgroup\$
    – Roger Miranda Perez
    Commented Dec 9, 2020 at 16:27

1 Answer 1

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According to this FCC test report for the LXZK-TX1021 remote control, this remote uses HF at 433.92 MHz.

In other words: it is not an IR remote; it uses radio, so it does not send any IR you can receive.

It did pass the test, though.

Apart from that, you should put a >20 kΩ pull-up resistor between 5 V and Out, and a small cap in parallel with the 100 μF, both as described in the datasheet, if you want to wire the receiver up correctly.

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    \$\begingroup\$ Of course the wiring of the IR receiver was also wrong, lacking the pull-up resistor. Kind of interesting that when really close there was apparently some interference coupling to either the receiver or the scope probe. \$\endgroup\$
    – Chris Stratton
    Commented Dec 9, 2020 at 17:06
  • \$\begingroup\$ If I buy a receiver (let's say, this decoding module) would I be able to get the same signal? I connected the original receiver signal to a oscilloscope and I got 400ns 5V, 750ns 0V (OFF); 750ns 5V, 400ns 0V (ON). \$\endgroup\$
    – Roger Miranda Perez
    Commented Dec 11, 2020 at 9:12

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