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Customer Service And Infra-Red (IR) Remote Controller

By on May 6, 2017
remote controller waveforms












This story started with an unpleasant – but unfortunately too frequent – customer service experience. Remember the quote: “Satisfied customers tell three friends, angry customers tell 3,000”… As electronic repairers you know this and will do your best to satisfy your customers. It is a matter of business survival and self-satisfaction.

Unfortunately this doesn’t seem to apply anymore to large companies as we have seen a degradation of service quality over the time, to the point that it became disastrous in some cases. A few days ago my TV remote controller stopped working. Changing the batteries did not solve the problem and I could not see any flashing IR light – looking through a camera – when pressing the buttons. As it was still under warranty and didn’t look easy to open without leaving traces, I decided to go to the shop where I bought the TV. It’s a big store and it was not busy. Half a dozen sales people were hanging around paying no attention to customers entering the premises, even turning their head into another direction if they would see one; I had to call one of them for service. As soon as I removed the remote controller from it’s envelop the man immediately said: “No, this not, this one cannot” and walked away before I had the opportunity to say a word!  I ran behind him and explained that I bought the TV from them a year ago and it was still under warranty. “You must go to the service center” the man said and, again, walked away. I had to run after him, again, and ask if he would, at least, give me the address of the service center. Reluctantly he went to a computer, brought the address on the screen, and told me to use my mobile phone camera to capture the address. Wow, what a service, I felt so unwelcomed and that guy was just eager to get rid of me. Thank you very much salesman, sorry to have disturbed your snooze… I learned my lesson, next time I go straight to Google and try to find the information myself.

I remember the time when large radio-TV and electrical appliances stores hired technicians to help customers with their technical queries. A few of my friends took this kind of job after their apprenticeship. Gradually this service disappeared, cost cutting of course, and the technicians were replaced with cheaper salespersons, most of them having no idea about technical matters. This was a different time, when customer service was considered as an important part of the sales, boosting the sales, instead of an annoying cost center…

The following day I went to the service center and learned that I had to buy a new remote controller because it was not included in the warranty. What do you expect, warranty/extended warranty never covers the parts that are more likely to fail! Anyway the service was OK and I got a new remote controller in less than two days. And the good news is that now I was allowed to break open the old one!

 remote controller repair

This is the type of device where we need a blade or a mini-crowbar to take it apart! There are many videos on YouTube showing how to do it and they are very useful, if only to tell you if there are hidden screws, which was not the case for this model.

As expected, there is not much inside, an electrolytic capacitor, a smaller SMD capacitor, the IR LED transmitter and an IC. And the keypad of course! The capacitors and the IR LED tested OK. There were no damage, corrosion etc… on the keypad so the only possibility remained the IC. The IC is labeled ADAM27P16G and is a 4-bit single chip microcontroller. With software inside obviously, so nothing can be done to salvage the poor remote controller except recuperating the caps and the IR LED. fix remote controller

Nevertheless this minor incident gave me the idea of finding a bit more about those IR remote controllers. One might think that all it takes is to send a digital word made of ones and zeroes to a transmitting IR LED then collect the signal at the other end using a IR phototransistor and pronto.  Well, not any more, this might have been the way in earlier remote controllers but not anymore!

On the receiving side, TV, DVD etc… the designers usually specified an Infrared Receiver similar to the 1838T, which I will use for a couple of experiments: If you power the 1838T as shown below and connect its output to a LED through a 1k resistor you just built a simple remote controller tester… The LED will be flashing when you beam a remote controller at the device and press a key. And this works from far away, from the other end of the room for example. What a nice and easy remote tester, using only 3 components…

 remote controller circuit

On another end, if you beam a constant source of IR or white light (that contains IR in it) the circuit doesn’t seem to react. You might see a glitch when you turn on or off the light. The device is expecting a particular type of pulses, not any kind of pulse.

A glance at the datasheet shows that the IR receiver is a more complex circuit, designed to decode pulses made of bursts of a 38 kHz carrier frequency, as shown below: remote control waveform

The following figure shows the bloc diagram of the device. We can see that there is much more than a simple phototransistor… phototransistor circuit


What a clever idea. It makes the remote control totally oblivious to any type of optical interference such as ambient light or other kinds of light, but reacting only to its own specified pulses.

To measure this I added another detector to my test rig, a simple phototransistor, without any additional circuitry, which should show us the real signal while the output of the 1838T will show the signal after decoding:

 ir remote control test circuit

And here is what we can see on the oscilloscope: remote controller waveform

Channel 1 (Yellow) shows the signal as it is received and Channel 2 (Blue) shows the signal after decoding. Let’s have a closer look:

 remote control decoding waveform

How to interpret the digital output is another question. To avoid interferences between different devices, for example TV, DVD, sound system etc… manufacturers use different codes. There are also different protocols used by different brands. This normally works fine. However I remember a friend who was getting crazy as her ceiling fan was turning itself OFF randomly. She had it replaced, had the remote replaced, had the electrical installation checked, not to avail. It was during a gathering in her house to watch the football world cup that one of us noticed that the ceiling fan would stop when we changed the TV channel…

Some codes can be found at the following link:


Besides my whines about customer service (I had to get it out!), this short article demonstrated what happens behind the flashing IR LED that we can observe with our mobile phone camera. If you like to play with microcontrollers like Arduino or others, there are applications that allow you to read the codes of your remote controllers and even make your own remote. Have fun and be kind and patient with your customers.

gerald musy

Penang, Malaysia

Gerald Musy

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  1. Waleed Rishmawi

    May 6, 2017 at 3:47 pm

    very informative article. thanks for sharing

    • Gerald Musy

      May 7, 2017 at 9:49 pm

      Thanks for your support Waleed

  2. Albert van Bemmelen

    May 6, 2017 at 4:02 pm

    Great story Gerald! You wrote it in such colorful words it kept us reading on! And thank you for the elaborate electronic background on IR remote controllers. I have seen several projects on how to make a universal IR controller yourself, programmed in for instance Flowcode from Matrixmultimedia (UK). And I had a similar experience with my DVD-HDD recorder on which I had paid for an extended warranty time instead of the normal time on this device. And in that period my recorder was repaired once which involved replacing the DVD burner/player inside. After that warranty time I was invited by the insurance company to extend my warranty time with another year which I did. And a couple months later my recorder again had to be repaired. But I luckily had bought another year warranty time just before that. So I went to the store after my device was a second time repaired to get it back. What do you think?...they then told me that my recorder probably wasn't insured anymore and I had to pay them the costs of the repair upfront after which I had to claim my insurance afterwards. Altogether 130 euro's of which I only got about 110 euro's back AND immediately they cancelled my warranty (on which I still had 9 months left!) on the device afterwards. So I never buy from them again!

    • Gerald Musy

      May 7, 2017 at 9:54 pm

      Thanks for your support Albert. Sure that we all had similar experiences and this is a sad picture of the way customers are treated today. Not much we can do except to boycott bad service companies and promote the good ones.

  3. Paris Azis

    May 6, 2017 at 4:11 pm

    Hey Gerald

    Another interesting and well presented article as usually! Needless to say that my feelings about the already non existent service of companies selling electronics (and unfortunately not exclusively that kind of) appliances, coincide with yours...This is a bitter truth for all us as customers, but...
    Thanks for sharing this experience anyway. At least this softens somehow that bitterness!

    • Gerald Musy

      May 7, 2017 at 10:02 pm

      Thanks for your support Paris. Coming from you it has great value to me.
      Sometimes I think that I am suffering from "declinism" but your comments confirm that I am not the only one feeling the same.

  4. Albert van Bemmelen

    May 6, 2017 at 4:13 pm

    PS: there is another easier way to check any IR device. Just use an IR transmitter led on the BNC input channel of your oscilloscope. (IR leds also work the other way around as IR recievers). And since you already used your oscilloscope you wouldn't need any 1838T component this way.

  5. Mark

    May 6, 2017 at 7:49 pm

    Hey Gerald,
    Thanks for the detailed explanation on IR. I must admit, I haven't looked too deeply into it as I haven't had one fail yet, but it is great to know the code behind the simple flashes we see.
    And thanks for the heads up on the IR codes link.

    • Gerald Musy

      May 7, 2017 at 10:06 pm

      Thanks Mark, yes this is one of the thing we take for granted until we dig a bit deeper. An it is fun to discover how things work...

  6. MacDonald makwemba

    May 6, 2017 at 11:19 pm

    Thanks for sharing this article

    • Gerald Musy

      May 7, 2017 at 10:07 pm

      Thanks MacDonald

  7. Anthony

    May 7, 2017 at 5:19 am

    Thank you for a very interesting article Mr Gerald . I will print this and file in my library for future reference!

    Kind Regards

    • Gerald Musy

      May 7, 2017 at 10:09 pm

      Thanks for your support Anthony. Happy to read that it will be useful for you.

  8. moshe jacobson

    May 7, 2017 at 7:42 am

    Thanks Gerald...very nice article.

    • Gerald Musy

      May 7, 2017 at 10:10 pm

      Thanks Moshe, I appreciate your support.

  9. dicksy

    May 7, 2017 at 11:47 am

    Thanks Gerald..very good and usefull article

    • Gerald Musy

      May 7, 2017 at 10:12 pm

      Thanks for your support Dicksy

  10. Parasuraman S

    May 7, 2017 at 11:15 pm

    VOW! Great! A lot of new information learnt from your article!

    • Gerald Musy

      May 9, 2017 at 7:38 am

      Thanks for your support Parasuraman

  11. Robert Calk

    May 8, 2017 at 4:49 pm

    Good job, Gerald. Thanks for the article.

    • Gerald Musy

      May 9, 2017 at 7:39 am

      Thanks Robert. Hope to read from you soon.

  12. Tito Kanshulu

    May 8, 2017 at 7:34 pm

    Thanks for a well presented information Mr. Musy about the remote control, and thanks for reappearing. You have been quite for so long.

    • Gerald Musy

      May 9, 2017 at 7:41 am

      Thank you for your kind words Tito

  13. Alvaro rivillas.

    May 9, 2017 at 11:00 am

    very interesting article Gerald congratulations .

    • Gerald Musy

      May 11, 2017 at 10:51 am

      Thanks for your support Alvaro

  14. Geoffrey Wight

    May 10, 2017 at 10:39 pm

    Hi Gerald,

    Very entertaining & well written article! I have collected a significant number of remotes over the years, intent on one day repurposing them for other tasks then their original one. I have been gathering information to increase my understanding of the remote's function and your article gives a sweet clarity to it all.

    Do I understand things correctly, that the chip micro-controller's software was corrupted and that was why a repair could not be made?

    Do keep writing!

    • Gerald Musy

      May 11, 2017 at 11:05 am

      Hi Geoffrey,
      Thanks for your support and comments. Well the conclusion that the micro-controller was faulty simply came from the fact that all the other components were OK. We could investigate further providing we would have a programmer for that IC and some kind of development environment. Then, if the software is simply corrupted it could be re-loaded, also providing you would get a copy from the remote's manufacturer, which I doubt.
      If you find out that several of your remotes use the same type of micro-controller it might be interesting to investigate how they are programmed and get the relevant equipment/software. That would allow you to re-program your remotes for other purposes. Interesting project indeed.

  15. Humberto

    May 11, 2017 at 11:52 am

    Excellent article Gerald, as usual. Keep on sharing your knowledgement with us.

    • Gerald Musy

      May 12, 2017 at 7:43 am

      Thank you for your support Humberto


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