Re: Garage Door Safety Sensors

Discussion in 'Electronic Design' started by Spehro Pefhany, Nov 27, 2011.

  1. On Sat, 26 Nov 2011 18:23:21 -0800 (PST), the renowned hrh1818
    <> wrote:

    >On Nov 26, 6:23 pm, Jim Thompson <To-Email-Use-The-Envelope-I...@On-My-
    >Web-Site.com> wrote:
    >> Garage Door Safety Sensors... anyone know how they work.
    >>
    >> I'm surfing my ass off, even perusing patents, but I can't find how
    >> they work.
    >>
    >> Each end has two wires, black and white.
    >>
    >> They are connected black-to-black and white-to-white, then connected
    >> to two terminals on the motor controller.
    >>
    >> I can't find a schematic for any portion of it.
    >>
    >> (I'd like to simply buy a set, provide my own equivalent to that in
    >> the door controller and use for a different purpose.)
    >>
    >> Anyone know how they work?
    >>
    >>                                         ...Jim Thompson
    >> --
    >> | James E.Thompson, CTO                            |    mens     |
    >> | Analog Innovations, Inc.                         |     et      |
    >> | Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
    >> | Phoenix, Arizona  85048    Skype: Contacts Only  |             |
    >> | Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
    >> | E-mail Icon athttp://www.analog-innovations.com|    1962     |
    >>
    >> I love to cook with wine.     Sometimes I even put it in the food.

    >
    >Some clues here
    >"Under U.S. federal law (UL 325), garage door openers manufactured for
    >the U.S. since 1993 must include a safety reversing system, such as
    >photoelectric eyes mounted no higher than six inches above the ground,
    >with a light beam spanning the door opening. The garage door opener is
    >required to reverse the door to the open position if the beam is
    >broken.[9] Other examples of safety reversing systems, allowed within
    >the guideline of UL 325, include electric safety edges, which reverse
    >with approximately 15 pounds of downward pressure, and a garage door
    >and opener system without photo eyes, tested together, which reverses
    >upon approximately 15 pounds of pressure.[10]" This is from
    >Wikipedia. See:
    ><http://en.wikipedia.org/wiki/Garage_door_opener#Safety>
    >
    >What mechanism is used in automatic reversing power windows in cars to
    >reverse direction when there is an obstruction?
    >
    >Howard


    I think they're just simple modulated IR beams with integrated IR
    demodulators (similar to IR remote control receivers), such as this
    one:

    http://www.biltek.tubitak.gov.tr/gelisim/elektronik/dosyalar/3/IR_sfh506.pdf

    All the rest of the smarts resides in a microcontroller.


    Best regards,
    Spehro Pefhany
    --
    "it's the network..." "The Journey is the reward"
    Info for manufacturers: http://www.trexon.com
    Embedded software/hardware/analog Info for designers: http://www.speff.com
    Spehro Pefhany, Nov 27, 2011
    #1
  2. Spehro Pefhany

    Winston Guest

    Spehro Pefhany wrote:

    (...)

    > I think they're just simple modulated IR beams with integrated IR
    > demodulators (similar to IR remote control receivers), such as this
    > one:
    >
    > http://www.biltek.tubitak.gov.tr/gelisim/elektronik/dosyalar/3/IR_sfh506.pdf
    >
    > All the rest of the smarts resides in a microcontroller.


    http://www.youtube.com/watch?v=GbmufXgpl14

    Short answer: It's like a 'one wire' protocol.

    Long answer:
    The 'transmitter' and 'receiver' are parallel-connected to
    a medium-pullup 5.5V DC source. The transmitter pulses an
    IRLED at a 154 Hz rate, 7.7% duty cycle.

    The receiver (probably just an IR filtered phototransistor)
    receives the pulses and pulls the DC source down to nearly
    zero volts in response to each received
    IR pulse. The microcontroller in the opener decides if it
    is getting the pulses sourced by the transmitter.

    Blockage of the light will result in a continuous 5.5 V
    present on the two wires. Continuous 0 V or 5.5 V is
    considered physical path interference and will prevent
    the door from closing unless the hard switch in the garage
    is held closed continuously.

    Clever!

    --Winston
    Winston, Nov 27, 2011
    #2
  3. On Sat, 26 Nov 2011 20:33:53 -0800, the renowned Winston
    <> wrote:

    >Spehro Pefhany wrote:
    >
    >(...)
    >
    >> I think they're just simple modulated IR beams with integrated IR
    >> demodulators (similar to IR remote control receivers), such as this
    >> one:
    >>
    >> http://www.biltek.tubitak.gov.tr/gelisim/elektronik/dosyalar/3/IR_sfh506.pdf
    >>
    >> All the rest of the smarts resides in a microcontroller.

    >
    >http://www.youtube.com/watch?v=GbmufXgpl14
    >
    >Short answer: It's like a 'one wire' protocol.
    >
    >Long answer:
    >The 'transmitter' and 'receiver' are parallel-connected to
    >a medium-pullup 5.5V DC source. The transmitter pulses an
    >IRLED at a 154 Hz rate, 7.7% duty cycle.
    >
    >The receiver (probably just an IR filtered phototransistor)
    >receives the pulses and pulls the DC source down to nearly
    >zero volts in response to each received
    >IR pulse. The microcontroller in the opener decides if it
    >is getting the pulses sourced by the transmitter.
    >
    >Blockage of the light will result in a continuous 5.5 V
    >present on the two wires. Continuous 0 V or 5.5 V is
    >considered physical path interference and will prevent
    >the door from closing unless the hard switch in the garage
    >is held closed continuously.
    >
    >Clever!
    >
    >--Winston


    I think you'll find the transmitter supplies a pulsed IR light carrier
    in the tens of kHz range to match the reciever.

    It would be interesting to see if the carrier is pulsed or not without
    the receiver- too bad he didn't hook a photodiode to his 'scope. Maybe
    someone has this type of garage door opener and can take a
    measurement?

    The receiver has an integrated receiver module inside. It pulls its
    own power supply down (and the transmitter's power supply) when the
    carrier is detected.

    (but presumably there's a diode + cap in each module to keep at least
    the receiver alive for a few msec. There has to be current limiting in
    the base unit- maybe a zener shunt regulator and pullup to +24 or
    whatever.



    Best regards,
    Spehro Pefhany
    --
    "it's the network..." "The Journey is the reward"
    Info for manufacturers: http://www.trexon.com
    Embedded software/hardware/analog Info for designers: http://www.speff.com
    Spehro Pefhany, Nov 27, 2011
    #3
  4. On Sun, 27 Nov 2011 00:16:51 -0500, the renowned Spehro Pefhany
    <> wrote:

    >On Sat, 26 Nov 2011 20:33:53 -0800, the renowned Winston
    ><> wrote:
    >
    >>Spehro Pefhany wrote:
    >>
    >>(...)
    >>
    >>> I think they're just simple modulated IR beams with integrated IR
    >>> demodulators (similar to IR remote control receivers), such as this
    >>> one:
    >>>
    >>> http://www.biltek.tubitak.gov.tr/gelisim/elektronik/dosyalar/3/IR_sfh506.pdf
    >>>
    >>> All the rest of the smarts resides in a microcontroller.

    >>
    >>http://www.youtube.com/watch?v=GbmufXgpl14
    >>
    >>Short answer: It's like a 'one wire' protocol.
    >>
    >>Long answer:
    >>The 'transmitter' and 'receiver' are parallel-connected to
    >>a medium-pullup 5.5V DC source. The transmitter pulses an
    >>IRLED at a 154 Hz rate, 7.7% duty cycle.
    >>
    >>The receiver (probably just an IR filtered phototransistor)
    >>receives the pulses and pulls the DC source down to nearly
    >>zero volts in response to each received
    >>IR pulse. The microcontroller in the opener decides if it
    >>is getting the pulses sourced by the transmitter.
    >>
    >>Blockage of the light will result in a continuous 5.5 V
    >>present on the two wires. Continuous 0 V or 5.5 V is
    >>considered physical path interference and will prevent
    >>the door from closing unless the hard switch in the garage
    >>is held closed continuously.
    >>
    >>Clever!
    >>
    >>--Winston

    >
    >I think you'll find the transmitter supplies a pulsed IR light carrier
    >in the tens of kHz range to match the reciever.
    >
    >It would be interesting to see if the carrier is pulsed or not without
    >the receiver- too bad he didn't hook a photodiode to his 'scope. Maybe
    >someone has this type of garage door opener and can take a
    >measurement?
    >
    >The receiver has an integrated receiver module inside. It pulls its
    >own power supply down (and the transmitter's power supply) when the
    >carrier is detected.
    >
    >(but presumably there's a diode + cap in each module to keep at least
    >the receiver alive for a few msec. There has to be current limiting in
    >the base unit- maybe a zener shunt regulator and pullup to +24 or
    >whatever.


    Okay. patents.

    US5465033 illustrates an early higher voltage implementation that has
    the parallel transmitter/receiver configuration.

    Looks like US6906307 is pretty much what is used now- the transmitter
    circuitry is in one module and the photo detector, amplifier, AGC,
    detector is in another.

    Looks like the transmitter sends continously so long as power is
    applied (and the beam is not received in the parallel configuration).

    It _is_ a clever arrangement- sort of a windowed watchdog timer that
    depends on the modulated optical path for feedback. Very, very
    unlikely to accidentally fail in a state which indicates an unblocked
    door, despite using cheapie parts in most spots (and a few
    redundant-for-reliability parts around the micro).



    Best regards,
    Spehro Pefhany
    --
    "it's the network..." "The Journey is the reward"
    Info for manufacturers: http://www.trexon.com
    Embedded software/hardware/analog Info for designers: http://www.speff.com
    Spehro Pefhany, Nov 27, 2011
    #4
  5. Spehro Pefhany

    Winston Guest

    The incomparable Spehro Pefhany wrote:
    > On Sun, 27 Nov 2011 00:16:51 -0500, the renowned Spehro Pefhany
    > <> wrote:
    >
    >> On Sat, 26 Nov 2011 20:33:53 -0800, the renowned Winston
    >> <> wrote:
    >>
    >>> Spehro Pefhany wrote:
    >>>
    >>> (...)
    >>>
    >>>> I think they're just simple modulated IR beams with integrated IR
    >>>> demodulators (similar to IR remote control receivers), such as this
    >>>> one:
    >>>>
    >>>> http://www.biltek.tubitak.gov.tr/gelisim/elektronik/dosyalar/3/IR_sfh506.pdf
    >>>>
    >>>> All the rest of the smarts resides in a microcontroller.
    >>>
    >>> http://www.youtube.com/watch?v=GbmufXgpl14
    >>>
    >>> Short answer: It's like a 'one wire' protocol.
    >>>
    >>> Long answer:
    >>> The 'transmitter' and 'receiver' are parallel-connected to
    >>> a medium-pullup 5.5V DC source. The transmitter pulses an
    >>> IRLED at a 154 Hz rate, 7.7% duty cycle.
    >>>
    >>> The receiver (probably just an IR filtered phototransistor)
    >>> receives the pulses and pulls the DC source down to nearly
    >>> zero volts in response to each received
    >>> IR pulse. The microcontroller in the opener decides if it
    >>> is getting the pulses sourced by the transmitter.
    >>>
    >>> Blockage of the light will result in a continuous 5.5 V
    >>> present on the two wires. Continuous 0 V or 5.5 V is
    >>> considered physical path interference and will prevent
    >>> the door from closing unless the hard switch in the garage
    >>> is held closed continuously.
    >>>
    >>> Clever!
    >>>
    >>> --Winston

    >>
    >> I think you'll find the transmitter supplies a pulsed IR light carrier
    >> in the tens of kHz range to match the reciever.


    I imagine that Chamberlain and Genie, etc. use different frequencies.
    The patent you cite (US5465033) indicates 1400 Hz in one embodiment.
    (Column 5, line 39, 46) So apparently they split the difference. :)

    I *do* see 30 KHz tossed out as a possible frequency in US6906307,
    however. The pulse repetition rate does not matter, as long as
    the respective circuits are adjusted to accommodate it, IMHO.

    >> It would be interesting to see if the carrier is pulsed or not without
    >> the receiver- too bad he didn't hook a photodiode to his 'scope. Maybe
    >> someone has this type of garage door opener and can take a
    >> measurement?


    I'm interested, too.

    >> The receiver has an integrated receiver module inside. It pulls its
    >> own power supply down (and the transmitter's power supply) when the
    >> carrier is detected.


    'Hardwired single-frequency RFID' is how I think of it.

    >> (but presumably there's a diode + cap in each module to keep at least
    >> the receiver alive for a few msec. There has to be current limiting in
    >> the base unit- maybe a zener shunt regulator and pullup to +24 or
    >> whatever.


    The diode and cap you mention popped into my head as well.

    > Okay. patents.
    >
    > US5465033 illustrates an early higher voltage implementation that has
    > the parallel transmitter/receiver configuration.
    >
    > Looks like US6906307 is pretty much what is used now- the transmitter
    > circuitry is in one module and the photo detector, amplifier, AGC,
    > detector is in another.


    I see they use the phrase 'one wire' to describe the
    design. Where did I hear that before? :)

    > Looks like the transmitter sends continously so long as power is
    > applied (and the beam is not received in the parallel configuration).


    I suspect we will find that the transmitter sends it's
    pulses regardless of whether the pulses are received.

    > It _is_ a clever arrangement- sort of a windowed watchdog timer that
    > depends on the modulated optical path for feedback. Very, very
    > unlikely to accidentally fail in a state which indicates an unblocked
    > door, despite using cheapie parts in most spots (and a few
    > redundant-for-reliability parts around the micro).


    At the risk of revealing the blindingly obvious,
    a broken wire to either sensor puts the unit in fail-
    safe mode and forces it to act as if an obstruction
    is in place. That is nifty IMHO.

    Back atcha, Speff.

    --Winston
    Winston, Nov 27, 2011
    #5
  6. Spehro Pefhany

    Joerg Guest

    Jim Thompson wrote:
    > On Sat, 26 Nov 2011 20:33:53 -0800, Winston <>
    > wrote:
    >
    >> Spehro Pefhany wrote:
    >>
    >> (...)
    >>
    >>> I think they're just simple modulated IR beams with integrated IR
    >>> demodulators (similar to IR remote control receivers), such as this
    >>> one:
    >>>
    >>> http://www.biltek.tubitak.gov.tr/gelisim/elektronik/dosyalar/3/IR_sfh506.pdf
    >>>
    >>> All the rest of the smarts resides in a microcontroller.

    >> http://www.youtube.com/watch?v=GbmufXgpl14

    >
    > That clinches it. I'm "new and improving" the acoustic Doppler
    > parking distance gadget... it's too variable to prevent the wife from
    > parking too close to the back wall of the garage.
    >


    Western solution: Bolt a 2-by-4 onto the floor, with the upper edges
    rounded off. Done :)

    [...]

    --
    Regards, Joerg

    http://www.analogconsultants.com/
    Joerg, Nov 27, 2011
    #6
  7. Spehro Pefhany

    Joerg Guest

    Jim Thompson wrote:
    > On Sun, 27 Nov 2011 10:21:05 -0800, Joerg <>
    > wrote:
    >
    >> Jim Thompson wrote:
    >>> On Sat, 26 Nov 2011 20:33:53 -0800, Winston <>
    >>> wrote:
    >>>
    >>>> Spehro Pefhany wrote:
    >>>>
    >>>> (...)
    >>>>
    >>>>> I think they're just simple modulated IR beams with integrated IR
    >>>>> demodulators (similar to IR remote control receivers), such as this
    >>>>> one:
    >>>>>
    >>>>> http://www.biltek.tubitak.gov.tr/gelisim/elektronik/dosyalar/3/IR_sfh506.pdf
    >>>>>
    >>>>> All the rest of the smarts resides in a microcontroller.
    >>>> http://www.youtube.com/watch?v=GbmufXgpl14
    >>> That clinches it. I'm "new and improving" the acoustic Doppler
    >>> parking distance gadget... it's too variable to prevent the wife from
    >>> parking too close to the back wall of the garage.
    >>>

    >> Western solution: Bolt a 2-by-4 onto the floor, with the upper edges
    >> rounded off. Done :)
    >>
    >> [...]

    >
    > American response... visitor stumbles over hack solution, sues :-(
    >


    Paint it fire engine red and write on it "Watch your step - Ver su paso".


    > (And we occasionally buy new vehicles... you wouldn't guess that,
    > since Q45 is 7 years old, truck is 11, but we do change :)
    >


    Easy. Drill a couple of new holes, re-arrange, patch old holes :)

    --
    Regards, Joerg

    http://www.analogconsultants.com/
    Joerg, Nov 27, 2011
    #7
  8. Spehro Pefhany

    Winston Guest

    Jim Thompson wrote:

    (...)

    > That's at least a start... apply a 5V supply with limited "moxie" and
    > _watch_ ;-)


    You meant to say 'unlimited moxie' yes? :)
    I agree that would heat things up a bit.

    There is a 'constant moxie controller' powering
    the transmitter. In US5465033 it is set up to limit
    at 62.5 milli moxies.

    'Works great!

    --Winston
    Winston, Nov 27, 2011
    #8
  9. Spehro Pefhany

    Guest

    On Sun, 27 Nov 2011 10:21:05 -0800, Joerg <> wrote:

    >Jim Thompson wrote:
    >> On Sat, 26 Nov 2011 20:33:53 -0800, Winston <>
    >> wrote:
    >>
    >>> Spehro Pefhany wrote:
    >>>
    >>> (...)
    >>>
    >>>> I think they're just simple modulated IR beams with integrated IR
    >>>> demodulators (similar to IR remote control receivers), such as this
    >>>> one:
    >>>>
    >>>> http://www.biltek.tubitak.gov.tr/gelisim/elektronik/dosyalar/3/IR_sfh506.pdf
    >>>>
    >>>> All the rest of the smarts resides in a microcontroller.
    >>> http://www.youtube.com/watch?v=GbmufXgpl14

    >>
    >> That clinches it. I'm "new and improving" the acoustic Doppler
    >> parking distance gadget... it's too variable to prevent the wife from
    >> parking too close to the back wall of the garage.
    >>

    >
    >Western solution: Bolt a 2-by-4 onto the floor, with the upper edges
    >rounded off. Done :)


    Hang a fishing practice weight (rubber plumb bob looking thing) on
    monofilament fishing line from the ceiling so it lines up with the center of
    the windshield (mirror mount is a nice target).
    , Nov 27, 2011
    #9
  10. On Sun, 27 Nov 2011 12:50:41 -0700, the renowned Jim Thompson
    <> wrote:

    >On Sun, 27 Nov 2011 11:26:23 -0800, Winston <>
    >wrote:
    >
    >>Jim Thompson wrote:
    >>
    >>(...)
    >>
    >>> That's at least a start... apply a 5V supply with limited "moxie" and
    >>> _watch_ ;-)

    >>
    >>You meant to say 'unlimited moxie' yes? :)
    >>I agree that would heat things up a bit.
    >>
    >>There is a 'constant moxie controller' powering
    >>the transmitter. In US5465033 it is set up to limit
    >>at 62.5 milli moxies.
    >>
    >>'Works great!
    >>
    >>--Winston

    >
    >In my lingo "limited moxie" means limited strength means current
    >limited ;-)
    >
    >The LM317 is set up as a current source.
    >
    >Further observance shows that a supply greater than 8.2V (current
    >limited) is needed to see the modulation (note the 8.2V zener (D1,
    >SK8V2).
    >
    > ...Jim Thompson


    Careful- I think there are at least two kinds of 2-wire sensors. One
    seems to run on high voltage and one on ~6V.

    Replacement parts refer to those with red and those with green LEDs
    being incompatible.


    Best regards,
    Spehro Pefhany
    --
    "it's the network..." "The Journey is the reward"
    Info for manufacturers: http://www.trexon.com
    Embedded software/hardware/analog Info for designers: http://www.speff.com
    Spehro Pefhany, Nov 27, 2011
    #10
  11. On Sat, 26 Nov 2011 23:45:05 -0800, the renowned Winston
    <> wrote:


    >I see they use the phrase 'one wire' to describe the
    >design. Where did I hear that before? :)


    Yup, you nailed it!

    >> Looks like the transmitter sends continously so long as power is
    >> applied (and the beam is not received in the parallel configuration).

    >
    >I suspect we will find that the transmitter sends it's
    >pulses regardless of whether the pulses are received.


    That is possible, but it would not be as good, IMHO. More complex and
    it would mean that the millisecond pulses are generated inside the
    receiver so an internal failure after the demodulator could cause a
    false "no obstruction" signal. Easy enough to test if someone had the
    bits- just use independent current-limited* supplies for each half.

    >> It _is_ a clever arrangement- sort of a windowed watchdog timer that
    >> depends on the modulated optical path for feedback. Very, very
    >> unlikely to accidentally fail in a state which indicates an unblocked
    >> door, despite using cheapie parts in most spots (and a few
    >> redundant-for-reliability parts around the micro).

    >
    >At the risk of revealing the blindingly obvious,
    >a broken wire to either sensor puts the unit in fail-
    >safe mode and forces it to act as if an obstruction
    >is in place. That is nifty IMHO.


    Yup, only two connections to the box and no combination of reversed,
    shorted, broken or damaged sensors can plausibly cause a false
    positive (or cause any damage or even much stress to the bits thanks
    to the current-limited supply and diodes).

    >Back atcha, Speff.
    >
    >--Winston


    * I'd build a little unbypassed current/voltage-limited supply rather
    than use a bench supply neat- there's always(?) a largish e-cap across
    the output terminals in the latter, and that could kill the receiver
    even if the supply limits the steady-state current. A resistor and
    6.2V zener should suffice for bench testing.


    Best regards,
    Spehro Pefhany
    --
    "it's the network..." "The Journey is the reward"
    Info for manufacturers: http://www.trexon.com
    Embedded software/hardware/analog Info for designers: http://www.speff.com
    Spehro Pefhany, Nov 27, 2011
    #11
  12. Spehro Pefhany

    legg Guest

    On Sun, 27 Nov 2011 10:32:51 -0700, Jim Thompson
    <> wrote:

    >On Sat, 26 Nov 2011 20:33:53 -0800, Winston <>
    >wrote:
    >
    >>Spehro Pefhany wrote:
    >>
    >>(...)
    >>
    >>> I think they're just simple modulated IR beams with integrated IR
    >>> demodulators (similar to IR remote control receivers), such as this
    >>> one:
    >>>
    >>> http://www.biltek.tubitak.gov.tr/gelisim/elektronik/dosyalar/3/IR_sfh506.pdf
    >>>
    >>> All the rest of the smarts resides in a microcontroller.

    >>
    >>http://www.youtube.com/watch?v=GbmufXgpl14

    >
    >That clinches it. I'm "new and improving" the acoustic Doppler
    >parking distance gadget... it's too variable to prevent the wife from
    >parking too close to the back wall of the garage.


    My solution was a ping pong ball suspended fro the roof. If it hit the
    windshield, she's a little closer than she prefers to be.

    No batteries, no wiring.

    RL
    legg, Nov 27, 2011
    #12
  13. Spehro Pefhany

    Guest

    On Sun, 27 Nov 2011 17:02:30 -0500, legg <> wrote:

    >On Sun, 27 Nov 2011 10:32:51 -0700, Jim Thompson
    ><> wrote:
    >
    >>On Sat, 26 Nov 2011 20:33:53 -0800, Winston <>
    >>wrote:
    >>
    >>>Spehro Pefhany wrote:
    >>>
    >>>(...)
    >>>
    >>>> I think they're just simple modulated IR beams with integrated IR
    >>>> demodulators (similar to IR remote control receivers), such as this
    >>>> one:
    >>>>
    >>>> http://www.biltek.tubitak.gov.tr/gelisim/elektronik/dosyalar/3/IR_sfh506.pdf
    >>>>
    >>>> All the rest of the smarts resides in a microcontroller.
    >>>
    >>>http://www.youtube.com/watch?v=GbmufXgpl14

    >>
    >>That clinches it. I'm "new and improving" the acoustic Doppler
    >>parking distance gadget... it's too variable to prevent the wife from
    >>parking too close to the back wall of the garage.

    >
    >My solution was a ping pong ball suspended fro the roof. If it hit the
    >windshield, she's a little closer than she prefers to be.


    Or a tennis ball. A bright yellow one.

    >No batteries, no wiring.
    >
    >RL
    , Nov 27, 2011
    #13
  14. On Tue, 29 Nov 2011 19:06:50 -0800, the renowned "Paul Hovnanian P.E."
    <> wrote:

    >Spehro Pefhany wrote:
    >
    >> On Sun, 27 Nov 2011 12:50:41 -0700, the renowned Jim Thompson
    >> <> wrote:
    >>
    >>>On Sun, 27 Nov 2011 11:26:23 -0800, Winston <>
    >>>wrote:
    >>>
    >>>>Jim Thompson wrote:
    >>>>
    >>>>(...)
    >>>>
    >>>>> That's at least a start... apply a 5V supply with limited "moxie" and
    >>>>> _watch_ ;-)
    >>>>
    >>>>You meant to say 'unlimited moxie' yes? :)
    >>>>I agree that would heat things up a bit.
    >>>>
    >>>>There is a 'constant moxie controller' powering
    >>>>the transmitter. In US5465033 it is set up to limit
    >>>>at 62.5 milli moxies.
    >>>>
    >>>>'Works great!
    >>>>
    >>>>--Winston
    >>>
    >>>In my lingo "limited moxie" means limited strength means current
    >>>limited ;-)
    >>>
    >>>The LM317 is set up as a current source.
    >>>
    >>>Further observance shows that a supply greater than 8.2V (current
    >>>limited) is needed to see the modulation (note the 8.2V zener (D1,
    >>>SK8V2).
    >>>
    >>> ...Jim Thompson

    >>
    >> Careful- I think there are at least two kinds of 2-wire sensors. One
    >> seems to run on high voltage and one on ~6V.
    >>
    >> Replacement parts refer to those with red and those with green LEDs
    >> being incompatible.

    >
    >Which brand? My Genie uses a pair of red LED/green LED units (the red LED
    >being the RX and green LED being the TX).


    This
    http://www.amazon.com/Liftmaster-41A4373A-Garage-Opener-Safety/dp/B0006N1RH6/ref=pd_sim_hi_6

    vs.

    This:
    http://www.amazon.com/Liftmaster-41A5034-Garage-Opener-Safety/dp/B00283XU7M/ref=pd_sim_hi_3





    Best regards,
    Spehro Pefhany
    --
    "it's the network..." "The Journey is the reward"
    Info for manufacturers: http://www.trexon.com
    Embedded software/hardware/analog Info for designers: http://www.speff.com
    Spehro Pefhany, Nov 30, 2011
    #14
  15. On Wed, 30 Nov 2011 09:28:48 -0700, Jim Thompson
    <> wrote:

    >On Sun, 27 Nov 2011 15:48:30 -0500, Spehro Pefhany
    ><> wrote:
    >
    >>On Sun, 27 Nov 2011 12:50:41 -0700, the renowned Jim Thompson
    >><> wrote:
    >>
    >>>On Sun, 27 Nov 2011 11:26:23 -0800, Winston <>
    >>>wrote:
    >>>
    >>>>Jim Thompson wrote:
    >>>>
    >>>>(...)
    >>>>
    >>>>> That's at least a start... apply a 5V supply with limited "moxie" and
    >>>>> _watch_ ;-)
    >>>>
    >>>>You meant to say 'unlimited moxie' yes? :)
    >>>>I agree that would heat things up a bit.
    >>>>
    >>>>There is a 'constant moxie controller' powering
    >>>>the transmitter. In US5465033 it is set up to limit
    >>>>at 62.5 milli moxies.
    >>>>
    >>>>'Works great!
    >>>>
    >>>>--Winston
    >>>
    >>>In my lingo "limited moxie" means limited strength means current
    >>>limited ;-)
    >>>
    >>>The LM317 is set up as a current source.
    >>>
    >>>Further observance shows that a supply greater than 8.2V (current
    >>>limited) is needed to see the modulation (note the 8.2V zener (D1,
    >>>SK8V2).
    >>>
    >>> ...Jim Thompson

    >>
    >>Careful- I think there are at least two kinds of 2-wire sensors. One
    >>seems to run on high voltage and one on ~6V.
    >>
    >>Replacement parts refer to those with red and those with green LEDs
    >>being incompatible.
    >>
    >>
    >>Best regards,
    >>Spehro Pefhany

    >
    >Spehro,
    >
    >Have you run across any specification that says, red/green sensors run
    >on a specific voltage?
    >
    > ...Jim Thompson


    Just what I am guessing from the patents I previously referenced and
    the video. One type is (from one patent and the video) six-ish volts,
    but I'm pretty sure there's a higher voltage type out there.
    Spehro Pefhany, Nov 30, 2011
    #15

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