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Thread: VR IN 67 ZX-IRM 38kHz IR receiver

  1. #1

    Default VR IN 67 ZX-IRM 38kHz IR receiver

    Does anyone have more details about the VR IN 67 ZX-IRM 38kHz IR receiver module offered by Vega Robokit?
    http://tinyurl.com/32zhulp

    What I'd like to know is -
    1. If it's suitable for continuous 38kHz pulses, unlike common remote control receivers which need discontinuous IR pulses.
    2. If the sensitivity (and therefore range) is comparable to popular modules like the TSOP1738.

    Thanks in advance for any input.

  2. #2

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    Have your tried asking vegakit?
    Last edited by pratheek; 06-23-2010 at 07:13 PM.
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  3. #3

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    No. I thought of asking for forum members' personal experience because, having been in electronics for a long long time in a remote corner of the country, most of my attempts to get information from Indian shops and companies have been exercises in futility.

    There have been a few exceptions, but most of the time, emails are simply ignored. It's not just about technical information. Enquiries about availability, prices, shipping, payment, etc simply remain unanswered 9 times out of 10. Even when they do reply, the points raised are usually not clarified. On the phone, what they say or promise often turn out to be unreliable. All of this is in complete contrast to my experience with foreign firms.

    OK. Anyway, I'll ask Vegakit.

  4. #4
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    Quote Originally Posted by Pimpom View Post
    No. I thought of asking for forum members' personal experience because, having been in electronics for a long long time in a remote corner of the country, most of my attempts to get information from Indian shops and companies have been exercises in futility. ...<snip>... All of this is in complete contrast to my experience with foreign firms.
    There is a simple reason... Tech/sales support costs money. This adds to the product cost. Compare Indian prices to foreign prices, don't add customs and freight. You'll find a huge difference in the prices of the same product. LM7805 on www.digikey.com for 1000 pieces is $ 0.241 (~ Rs. 11.00). You should get the same brand (National or Fairchild) for < Rs. 5.00 in Delhi/Mumbai.

    In fact, within Indian companies, you can see the difference. If you talk to a sales staff at Silicon Components, they'll help you make a component selection, point to datasheets, samples etc. Whereas if you talk to Cirkit Electro or others at Lamington Road, they will give you the stock position and price but hardly help you with a selection, part-alternatives, etc. Their support site is located at www.google.com. :-) Parts from Silicon Components in most cases costs 20% more than what Cirkit quotes. I have a comparative quotation which shows this for a fact. F.e. LM7805 for 250 pcs is Rs. 6.00 at Silicon and Rs. 4.9 from Cirkit.
    Last edited by MohitM; 06-24-2010 at 05:16 PM.
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  5. #5

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    I'm afraid I have to disagree. Please read my post again. The vast majority of enquiries I send to shops and companies are purchase questions, not requests for technical support. Most of my questions are in effect things like "Do you have items XYZ?", "How much?", "How do you want the payment sent?". How do they expect to sell things if they don't answer questions like that?

    If some shops are interested only in over-the-counter sales, fine. It's their choice. But my enquiries are to those who tout their goods on the internet, publishing their email addresses, inviting enquiries and telling everyone what good service they provide.

    I've dealt with foreign firms of all levels - one-man shows, small businesses, medium-sized ones and large corporations. 95% of all correspondences are answered promptly, courteously and to the point. They are not all large companies with high overheads and an army of highly paid staff.

    You mentioned Cirkit. I've visited Bombay/Mumbai several times over the past 20 years, sometimes staying for weeks. I've been into most of the shops on Lamington Road, Proctor Road, Chunam Lane, Kiln Lane, Tara Temple Lane, etc. I've visited and bought from Cirkit a number of times. But none of the emails I sent them received a reply.

  6. #6
    Super Moderator T-1000 docel's Avatar
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    Ok - this is veering Off-Topic !
    Did you ask Google?
    If you don't get any datasheet/information then why buy it ?
    Have you bought this board/ module ?
    docel
    ^Anything is possible..
    after YOU prove it!!

    http://bangalorerobotics.tripod.com

  7. #7

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    Quote Originally Posted by docel View Post
    Ok - this is veering Off-Topic !
    Sorry about that. I was letting off some steam after some 40 years of pent-up frustration.
    Did you ask Google?
    Yes. No luck. The part in question does not seem to be a product of some large manufacturer. There's one similar to it, but not quite the same.
    If you don't get any datasheet/information then why buy it ?
    Because I have not found a suitable one so far. All the readily available IR Rx modules I know of are not completely satisfactory as they require discontinuous pulses which slow down response times. I've used the available ones with a "make" response time of a few microseconds which is more than good enough. But I'd like to improve on the "break" response time which cannot be reduced to much below 1 millisec because of the minimum gap time between bursts.

    The alternative would be to design the receiver from scratch. But I need to send the IR beam over a large distance, and it will involve a fairly complex circuit for amplification, AGC, noise supression, etc. This is an important but one-off project and I'd like to avoid all the extra work if possible.
    Have you bought this board/ module ?
    No.

  8. #8
    Super Moderator T-1000 docel's Avatar
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    I don't think you asked Google politely.... I found quite a few pages ......!

    All IRMs have a specific purpose- to detect the 'wanted' signal & reject the unwanted (spurious signal).

    There is a difference between a IR diode and and IR module.
    The Ir diode is just that - a simple PN junction diode responding to the IR spectrum of light.
    This does not differentiate your source from other sources.

    The IR Module is more complex. It responds to IR light Modulated at some Specific Frequency.
    The 38Khz IRM does just that: It has a sunlight filter, Responds ONLY to IR light switched 38,000 times per sec.
    The Module has several units inside.
    One is the AGC . controlled by the filter output
    2nd is a Band pass filter- This responds to 38khz center frequency IR pulses and controls the AGC.
    3rd Integrator- produces a steadily changing output voltage for a constant input voltage.

    "The distinguishing mark between data signal and
    disturbance signal are carrier frequency, burst length
    and duty cycle." is what the Datasheet says.

    So, a constant 38khz signal will be detected at low gain ( low sensitivity ), a 38khz signal chopped ( Modulated ) 10times per second at high gain (hi sensitivity).

    A continuous 38khz will actually be rejected by the IRM by design.

    A 'burst' with a specific duty cycle will be accepted and passed on to the output.

    The remote control signal is a pulse train of several bits that must have a specified duty cycle and time for good response.

    All this means there is no way an IRM can do your job as specified by you.
    docel
    ^Anything is possible..
    after YOU prove it!!

    http://bangalorerobotics.tripod.com

  9. #9

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    Quote Originally Posted by docel View Post
    I don't think you asked Google politely.... I found quite a few pages ......!
    Of the particular module in question? If so, do you mind sharing the URLs?
    Or do you mean IRMs in general? If that, then I have dozens of datasheets of modules by Vishay, Sharp, Panasonic, etc.

    All IRMs have a specific purpose- to detect the 'wanted' signal & reject the unwanted (spurious signal).

    There is a difference between a IR diode and and IR module.
    The Ir diode is just that - a simple PN junction diode responding to the IR spectrum of light.
    This does not differentiate your source from other sources.

    The IR Module is more complex. It responds to IR light Modulated at some Specific Frequency.
    All of this is quite elementary and should be known to everyone except a novice on the subject. However.........

    The 38Khz IRM does just that: It has a sunlight filter, Responds ONLY to IR light switched 38,000 times per sec.
    Not quite. The module still responds to some extent to sunlight, incandescent light bulbs, etc. It's why I usually shield my modules with opaque material.

    The Module has several units inside.
    One is the AGC . controlled by the filter output
    2nd is a Band pass filter- This responds to 38khz center frequency IR pulses and controls the AGC.
    3rd Integrator- produces a steadily changing output voltage for a constant input voltage.

    "The distinguishing mark between data signal and
    disturbance signal are carrier frequency, burst length
    and duty cycle." is what the Datasheet says.
    Basic characteristics common to all standard IRMs. I was simply wondering if some manufacturer made a non-standard module that responds to continuous 38kHz pulses or one that requires only a short gap between bursts.

    So, a constant 38khz signal will be detected at low gain ( low sensitivity ), a 38khz signal chopped ( Modulated ) 10times per second at high gain (hi sensitivity).
    Not necessarily 10Hz. In past projects, I successfully used much higher chopping frequencies (>1kHz), but I'd like to go still higher. I usually lock my chopping frequency to the carrier frequency so that the former is an integral sub-multiple of the latter.

    A continuous 38khz will actually be rejected by the IRM by design.

    A 'burst' with a specific duty cycle will be accepted and passed on to the output.

    The remote control signal is a pulse train of several bits that must have a specified duty cycle and time for good response.
    True. And different models have different specs for duty cycle.

    All this means there is no way an IRM can do your job as specified by you.
    As I said before, I was wondering if there was some non-standard module with less stringent requirements for burst cycles.

  10. #10
    Super Moderator T-1000 docel's Avatar
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    Smile

    Your last post reminds me of a few things:

    I have always suspected that too much knowledge is a dangerous thing. It is a boon to people who don't have deep feelings; their pleasure comes from what they know. . . . But this only emphasizes the difference between the artist and the scholar.

    Margaret Anderson quotes

    http://forum.canibus-infinity.com/vi...hp?f=60&p=8609

    http://scienceblogs.com/principles/2...ain+Principles

    You seem to be quite knowledgeable, really ! And you have missed the answer to your query.

    Then, isn't it a little superfluous of you to be
    wondering if there was some non-standard module with less stringent requirements for burst cycles.
    Your quest for a non-professional component is quite preposterous indeed. Do you expect any manufacturer to make anything that is 'non-standard' or ' less stringent' as you put it ?
    Its up to you now, to decide whether you're a Scholar or an Artist !

    Good luck
    docel
    ^Anything is possible..
    after YOU prove it!!

    http://bangalorerobotics.tripod.com

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