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Infrared remote control repeater circuit

Discussion in 'Electronic Basics' started by [email protected], Apr 16, 2005.

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  1. Guest

    I've built the circuit shown at the following link:

    However, I seem to be having a problem regarding ambient light. I did
    make one change to the circuit. Since I couldn't find the SFH2030 IR
    detector diode, I used a Vishay BPV22NF with a daylight filter. Also,
    it might be worth noting that I used a wall wart to power the device
    instead of a battery. Anyway, the only way I can get the device to
    work is to completely turn all of the lights off in the room. Is there
    some way to get this to operate so that the circuit is insensitive to
    ambient light such as daylight and 60 Hz lighting? I'm new to IR
    circuits, but I'm guessing that this has something to do with the
    reverse bias levels on the IR detector diode, but I'm not sure. Any
    help would be appreciated.

    The reason I select this circuit was because I thought it was less
    prone to the effects of ambient light.
  2. Guest

    Well, I usually use the Panasonic IR detectors with the filtering and
    TTL logic as a unit. PNA4612 38.0 KHz running into a microcontroller. I
    looked at Andy's circuit and I don't see any reverse bias on the
    photodioide. If the opamp is functioning correctly, both inputs should
    be at the same DC level meaning 0 bias on the diode. Photo diodes have
    better speed and linearity with some reverse bias on them but then have
    dark current issues. It would seem to me that the signal should be AC
    coupled to reduce ambient light sensitivity. You're only interested in
    the pulsing. Just curious, how much range are you trying to get?
  3. Guest

    I'm looking for a range of about 15 to 20 feet. That works fine as
    long as the lights are out and ambient light is very minimal. I tried
    inserting a coupling capacitor between the diode and the opamp input,
    but it didn't help much.
  4. John Smith

    John Smith Guest

    I can't seem to find a datasheet for the SFH2030, but found this:
    where it says that the device can be used either as a photodiode (with
    suitable reverse biasing), or as a photovoltaic cell. I suspect your circuit
    is using it as the latter.
    The datasheet for the Vishay part doesn't mention the same capability.
  5. Guest

    Well, that makes sense. Thanks for your help.
  6. Guest

    Samsung and Sony remotes with the PNA4612 receiver easily reach 15-20
    feet, more like 25+. You do have to point it at the receive module but
    it is fine in normal room lights and during the day, provided direct
    sun is not on the receiver. Are you trying to get around obstacles? My
    HDTV Wonder came with the ATI remote wonder. This is an RF unit, not
    IR. I still have this urge to 'point' it at the computer but it makes
    no difference.
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