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Infrared Remote Control

Discussion in 'General Electronics Discussion' started by AnonyMouse, Jul 28, 2016.

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  1. AnonyMouse

    AnonyMouse

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    Apr 25, 2016
    At 99 years of age it's no surprise that my mother relies heavily on the Acorn chairlift mounted on the rear stairs of her high set Queenslander-style home. The chairlift is operated by toggles on the armrests, but was also supplied with two hand-held remote control units, and it makes sense in her situation for one to be kept upstairs and one downstairs.

    When one of the remotes went on the blink recently I discovered how difficult it would be to replace one in the event of loss, damage or terminal failure. The guy who had installed the chairlift was unable to get the failed unit working, and bought along several units from his box of spares, none of which worked at first. He was eventually able to get one working so we again have the necessary two remotes.

    Incidentally, the chairlift was purchased secondhand from an aged care service provider, so the manufacturer isn't compelled to play any part in support. I have tried to contact them about purchasing a spare remote but cannot even get a reply.

    Anyway, that experience got me thinking about possible future problems, as it seems unlikely that the installer would be able to provide a replacement next time round.

    By chance he left behind the original unit that had failed. By viewing the business end of that remote through my mobile phone camera lens I can see the three infrared lenses lighting up when either the Up or Down button is pressed, so there is definitely some signal being transmitted.

    I'm not 100% sure where I'm trying to go with this, but I'm wondering if there is some way to read the signal being transmitted by one of the good remotes, and compare it to the signal being transmitted by the dud.

    And even if so, where to then? Would it be possible to build a basic remote that transmitted the required signal. Compact size wouldn't matter, it could be as big as a shoe box, just so long as it worked.
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    Try a "teachable universal infrared remote control" (one that can "learn" codes from an existing control). These take the IR signal from an existing control, store it internally and replay the signal when the correspondig button is pressed.
    Or look for an original spare remote control e.g. on ebay.
     
    sundy, hevans1944 and AnonyMouse like this.
  3. AnonyMouse

    AnonyMouse

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    Apr 25, 2016
    Thanks Harald.

    A possible problem that occurred to me is that the Acorn stairlift remotes have three (3) IR LEDS, all of which light up.

    All the "teachables" that I can find have a single LED.
     
  4. Harald Kapp

    Harald Kapp Moderator Moderator

    11,413
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    Nov 17, 2011
    This is very likely to increase IR brightness and thus range. I very much doubt these 3 LEDs send different signals. You may need higher brightness if you want to e.g. call the stairlift from above when it is downstairs, provided the IR receiver is mounted to the chair (not separate receivers on ground and first flight).
    Only a test can show whether this is necessary. On the other hand: how likely ist your mom going to be upstairs with the lift downstairs or vice versa?

    There's still the chance to fina a working spare on the internet.
     
  5. Sunnysky

    Sunnysky

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    Jul 15, 2016
    IR emitters can work by bouncing off walls if aimed properly and battery is good
    But 3 emitters gives better spread as they tend to be low beamwidth e.g. +/-10deg)
    Most are single these days, so it may be difficult to find.

    3 requires more battery voltage as they tend to pulse 100mA and run them in series Vf~1.5V usually with 4 AA cells and a series R.

    Usually they will have DIP switches inside to select the address of the unique unit.
    Did he check that?
     
    Last edited: Jul 28, 2016
  6. 73's de Edd

    73's de Edd

    3,081
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    Aug 21, 2015
    Sir AnonyMouse . . . . . . .

    OK . . .in reviewing the already givens:

    You had two working remotes . . .one stopped . . .the other still worked.
    The repairman . . . . with an unknown degree of finesse with YOUR particular brand . . .supplied an additional working remote.
    You still have the non working remote, which a display on a camera confirmed IR emissions . . .but UNSURE of its digital coding.


    Take this OH-FISH-ULL ACORN info below, and confirm if its procedure corrects that inoperative remote .
    If it DOES, you may then have to go back and re check the other two units..


    Acorn Users manual Remotes.png



    That's it . . .

    73's de Edd
     
    Last edited by a moderator: Aug 4, 2016
    Harald Kapp likes this.
  7. AnonyMouse

    AnonyMouse

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    Apr 25, 2016
    Once one of these chairs is installed you'll find yourself using them for purposes other than just as a people carrier. For example they are very useful for sending groceries up and garbage bags down.

    While there are quite a few advertisements for complete secondhand stair lifts (even for this exact model), I have not been able to find any ads for Acorn brand remote control units on their own.

    Yes, I watched the installer doing the dip switch thing on several secondhand units before he got to one that worked. Since then I have personally checked that the dip switches on the non-operating unit are set the same as those on one of the working units.

    That's obviously for a different model. My mother's unit is an Acorn SuperGlide 130, and the equivalent instructions for it are:

    ... you can reset the remote control by sending the carriage to the bottom of the track. Then turn the seat so that the digital display is showing 'E5'.

    Press the paddle on the chair arm in the DOWN direction (even though the stairlift will not move any further) and, at the same time, press the UP button on the remote control for approximately 5 SECONDS.
    etc etc

    And yes, we have been through all that. I can only conclude now that the remote control unit is actually faulty.

    Looks like my only option now is to risk 30 or 40 bucks on one of those programmable remotes as recommended by Harald and see if it will work.
     
  8. HellasTechn

    HellasTechn

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    Apr 14, 2013
    One thing i would have checked is this. Open the case and observe for a crystal (in remote controls it is common the crystal to be a small sqare plastic with two leads) if indeed there is one get a new one from your loacal electronics shop and replace it.

    Why i suggest this ? if the crystal is not broken but cracked (due to a fall) then the carrier freq that the remote transmitts will have shifted and that may explain why you see transmittion but no response.
     
  9. 73's de Edd

    73's de Edd

    3,081
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    Aug 21, 2015
    Sir AnonyMouse . . . . . . .

    ( http://www.waveevents.com/MyFilez/wavs/cartoon/mightymo.wav )

    OK on the slight 120 vs 130 model difference . . . . but, even then, your tried procedure, produced no favorable result . . . when using it.

    Now, in taking a little further trip down the intelligentsia trail . . . . with your having but bare necessities available for use . . . yet . . . trying to accomplish all that is possible, by most effectively using them.

    Since we are totally blind-dumb and deaf at this end, how many slides / rocker tabs are on the reeee-mote controls dippity-dip-dip switch?

    Your camera confirmed IR emissivity . . .but would be of no help in the differentiation . . .or presence . . . . of the stream of fast 38 khz pulses that it is being modulated with.

    Visual:

    This is a scoping of the stream of narrow and wide 38Khz pulses that modulate . . . .rapidly turn on and off . . . . your infrared LED trio.

    [​IMG]


    To accomplish confirmation of there being a modulation presence, lets rely upon the fast rise times of those aforementioned generated 38 Khz pulses that will additionally create harmonics that extend W A A A A A Y on up into the low frequency RF/Radio spectrum.
    Specifically . . .up around 550Khz on upwards to 1Mhz, is being our spectrum of interest.
    That will coincide with the lower band of an AM radio receiver which I hope that you have and can find it as being a pocket portable or a bit larger portable.
    In either case, they will be utilizing an internal ferrite loop antenna that collects and concentrates received RF energy within its small physical area.

    To Evaluate:

    Turn on the radio and place down near 550 or where NO AM radio station is being picked up, then max up the volume and bring one of the working remotes up near / kissing the radio and press a remote button repetitively.
    You should hear a raspy tonal burst, THEN you move the remote ALL around the radio and try
    all positions to get the strongest signal being received.
    Congratulations, you have now found the internal loop antennas physical positioning and the "hot" spot on the remote hand unit. Make deep observation and take mental note.

    Relevant factoid:

    If you were to hear the "buzzzzz" of a housefly . . . .a mosquito . . . .a bumblebee you could differentiate them with your hearing acuity . . . . the same will be true in the case of the sequencing of these wide and narrow tone bursts, along with their arrangements.

    An unknown variable . . . being left for you to evaluate.
    Most remotes put out repetitive, yet identical tonal bursts when a remote button is constantly held down, confirm that this is true in your case.
    (A rare case is for a single tonal blip being produced until the . . .or another . . . key is pressed again.)

    Figuring that the first situation is being your case . . .get your TWO working remotes and hold them side by side, sharing that most sensitive / receptive position of the radio.
    Press the UP button for one pulse blip and the like button on the other unit . . .they sound the same don't they ?
    Then to FULLY test your aural acuity and tonal differentiation, change to pressing one remotes UP and the other ones DOWN.
    Your brain should then tell you . . .Hey! . . . .I can HEAR the difference, when I am hearing one immediately after the other..
    And then . . . .AND THEN . . . . you try that test sequence, using one good remote unit and that questionable unit, keying identical buttons alternatively on each remote..

    Feedback time . . . . to see which multi branched trail to follow from here.


    73's de Edd
     
    Last edited by a moderator: Aug 4, 2016
  10. AnonyMouse

    AnonyMouse

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    Apr 25, 2016
    Covering 1 or 2 of the 3 IR LEDs does not prevent the remote unit from operating, so long as one LED is pointed at the chairs receiver. Thus it seems that Harald is correct about the extra LEDs being for amplification, which increases my confidence that a programmable TV remote might work.

    No such crystal that I can see. I'll insert a photo of the PCB.

    The dip switch is comprised of two rockers (see image below). I do not have AM radio around here, though I could probably borrow one. But, academically interesting as it may be, I don't see where all that audio analysis would be getting me as far as a solution is concerned.

    I finally got through to Acorn in Australia and this time encountered a helpful lady. Contrary to what I had previously been told, I can indeed purchase a spare new remote control for the SuperGlide 130 - A$40 + A$11 postage. However if I can find a programmable remote at a cheap price I'll try that route as a matter of interest.

    [​IMG]
     
  11. HellasTechn

    HellasTechn

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    Apr 14, 2013
    Yes. some do have one while other dont.

    If i where you i would do the same.

    I think this method will help you understand if the "bad" remote is transmitting the correct code by comparing the audio generated after each button press of the "good" and the "bad" remote.
     
  12. 73's de Edd

    73's de Edd

    3,081
    1,301
    Aug 21, 2015
    Sir AnonyMouse . . . . . . .

    You say . . . .
    I don't see where all that audio analysis would be getting me as far as a solution is concerned.


    Hmmmmm. . . . .I could have started out with:

    FIRST . . . .
    You need to get yerselfs a XXX hundreds (or) some are thousands of dollars, triggered oscilloscope or PREFERABLY, a STORAGE version of same and THEN you tie it into an infrared converter/detector unit to observe the serial data train info being emitted by the hand units IR LED's.

    Then that will confirm IF a serial pulse train IS actually being created, and then by the comparison of the alternate . . .either wide or narrow pulse combinations . . . . . that they are being correct for the pressed pushbutton function.

    OR . . . .
    as Sir Hellas Tech.so aptly confirmed, hearing one known good units signal, immediately followed by a comparison from the suspect unit will confirm an identicallness of those same distinctive raspy tones.
    Or if you would have tried it . . . . . a proper response would have been:
    DAMN . . . . .that's one diabolically clever and simple scheme to avert a much more costly and complex testing alternative.

    BTW . . . HT . . . . ..I also saw neither crystal or ceramic resonator presence near the primary U1 IC.
    That single U2 presence/proximity sort of suggests it to be associated with the coding .

    F.I.O. . . .
    Magging the photo reveals 3 series arranged IR emitters, initially being fed from R4 and then over to their their Q2 driver and the incoming drive via R5, is coming up from the output of U1.
    Very limited codes to worry about, with only 2 DIP sections positions.


    73's de Edd
     
    Last edited by a moderator: Aug 4, 2016
  13. Alec_t

    Alec_t

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    Jul 7, 2015
    Obviously you've checked the failed remote with a fresh battery?
     
  14. AnonyMouse

    AnonyMouse

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    Apr 25, 2016
    :eek:
     
  15. sundy

    sundy

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    Aug 5, 2016
    X2 on the learning remote.
    Have you thought about installing toggle switches? One at the top and one at the bottom would be good insurance against further IR remote control failures.
     
  16. AnonyMouse

    AnonyMouse

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    Apr 25, 2016
    Not sure what you mean. What do the switches connect to?
     
  17. 73's de Edd

    73's de Edd

    3,081
    1,301
    Aug 21, 2015
    .


    Sir AnonyMouse . . . . . . .et . . .Sir Sundy

    I'm sure that its relevant to surmising that hard wired activation switches might be placed at the very top and bottom of the stairway for manually starting the cycling of a chair movement.
    HOWEVER . . .his not yet perceived aspect / situation, is that the lifts "POD" under the seat is all being self contained and has no connection to the "outside world," other than the mechanical connections to the wall rails AND the 2 electrical connections to DC power, for charging the units internal battery, when the unit is at either extreme docked position.
    All connections of the MANUAL up- down- stop switches are on the "pod" and only go inside of the POD and no farther,
    Any incoming Infrared signal also only goes into the "POD" and has no external connection.


    73's de Edd


    (Tried the AM radio monitoring yet? )
    .
     
    Last edited: Aug 8, 2016
  18. sundy

    sundy

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    Aug 5, 2016
    Yes a switch at the top and bottom that parallel the switches on the chair. I am assuming an electrical connection that is not on the stairwell but at either the top or bottom. A reticulated cord or some sort of wire way would be required to run the wire to the top and bottom.
     
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