4

I bought an IR repeater with the simple schematic:

Enter image description here

What is this receiver component? It looks almost like TSOP4838, has the same pinout, but it outputs an encoded signal and I cannot find what is it.

TSOP4838 (right) and this one (left)

Enter image description here

Back side:

Enter image description here

Short update: any part that does the same will be OK for my needs. Is there any?

Peter Mortensen
  • 1,676
  • 3
  • 17
  • 23
BUKTOP
  • 212
  • 1
  • 8
  • The interesting side of those components isn't the one you show, there should be text on the back indicating the part number. I am unsure what you mean by "outputs encoded signal", 9 out of 10 times, if you apply 5 V between GND and VS and an LED with 470 ohm series resistor between OUT and GND, you can make the LED flash when illuminating this receiver with any ordinarty (TV) remote. – Bimpelrekkie May 20 '19 at 06:37
  • It would be nice and easy if there’s any. But no, there’s none. That’s why I didn’t post the picture of the other side - there’s nothing on it unfortunately. Nothing at all. But I’ll update the question, thank you! – BUKTOP May 20 '19 at 06:39
  • @Bimpelrekkie by"encoded" I meant the raw 38 kHz signal. The ordinary 4838 outputs decoded signal: DESCRIPTION The TSOP22.., TSOP48.., TSOP24.. and TSOP44.. series are miniaturized IR receiver modules for infrared remote control systems. A PIN diode and a preamplifier are assembled on lead frame, the epoxy package contains an IR filter. The demodulated output signal can be directly connected to a microprocessor for decoding. – BUKTOP May 20 '19 at 06:45
  • 1
    @Bimpelrekkie maybe my explanations ain't clear, you can see the diagrams here https://www.vishay.com/docs/82459/tsop48.pdf The signal is 38 kHz pulse modulated, the standard chip outputs decoded/demodulated signal that cannot be directly used in repeater. This one outpuths the same signal it receives. – BUKTOP May 20 '19 at 06:47
  • 1
    I have used similar ones before, no need to explain what they are. The TSOP4838 outputs an unmodulated signal, the 38 kHz is removed, see figure 3 on page 3 of the datasheet. If you do measure 38 kHz at the output, that receiver isn't a TSOP48xx. Without a proper markings on the device it is anyone's guess what it is. – Bimpelrekkie May 20 '19 at 06:58
  • @Bimpelrekkie well, any part that works like this will be ok. The problem is, I cannot find any. I need such a repeater and don’t want to unsolder 20 pcs or that for 20 repeaters my friend asked me to make ;) – BUKTOP May 20 '19 at 07:01
  • Unfortunately asking for specific parts is **off topic**. You bought repeater so why not simply buy 20 of those, unclear what you're trying to achieve. – Bimpelrekkie May 20 '19 at 07:17
  • I need to embed this in my project. It’s strange to buy 20 devices just to unsolder one part of it ))) surely it’s possible, but I supposed it’s much easier just to find the part i need. – BUKTOP May 20 '19 at 07:20

1 Answers1

8

You will want to investigate the following web page at Vishay.

http://www.vishay.com/ir-receiver-modules/repeater/

At that page there is a section that links you to IR Receivers that are designed for use in repeaters or IR learning applications.

enter image description here

The parts offered on the repeater page are specifically designed to operate at a 38kHz carrier frequency. The part number TSMP4138 looks to be closest to the package type that you are looking for.

enter image description here

From the part data sheet the internal block diagram looks like this:

enter image description here

From the same data sheet the recommended application circuit for a repeater is shown as:

enter image description here

Michael Karas
  • 56,889
  • 3
  • 70
  • 138
  • Wow, thank you! That's it definitely! Thank you so much! – BUKTOP May 20 '19 at 09:00
  • 4
    @BbIKTOP - Take special note to use the two transistor NPN circuit to drive the IR LEDs. This design keeps the output voltage swing at the output of the IR repeater receiver to just the Vbe drop of the first transistor. This helps eliminate possible voltage coupling inside the receiver. The design that you showed in your question with the PNP transistor will be having a full Vcc swing on the output of the receiver which could lead to internal coupling. I would trust Vishay's recommended circuit as they are the experts in this field over the penny pinching design of some no name repeater. – Michael Karas May 20 '19 at 09:09
  • It’s just a details, no problem to use 2 transistors, the problem was to find the right sensor. I had the same problem with pwm fan (pwm control and sensors) in the same project, so I understand what are you talking about. Thank you! – BUKTOP May 20 '19 at 09:56
  • Interesting part, never knew such had been made just for repeaters. I would have added in a new carrier generator to re-modulate the demodulated baseband signal. Obviously this method avoids the bit edge jitter resulting from the re-modulation so is superior in most cases. Carrier phase jitter may be more but should be irrelevant. – KalleMP May 20 '19 at 22:15