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Wireless doorbell help

Discussion in 'General Electronics Discussion' started by Robertfhegreatnewb, Apr 17, 2016.

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  1. Robertfhegreatnewb


    Apr 17, 2016
    Need to know what components I can take out without damaging it.

    First pic is the remote
    Second one is the reciever
  2. Robertfhegreatnewb


    Apr 17, 2016
  3. Robertfhegreatnewb


    Apr 17, 2016
  4. hevans1944

    hevans1944 Hop - AC8NS

    Jun 21, 2012
    It appears you have already removed "some components" (the cases) so what more do you wish to DO? And why?
  5. Robertfhegreatnewb


    Apr 17, 2016
    I plan on doing an RF remote that can turn a buzzer on and off using this wireless doorbell. What should I do? I'm new at this and only have a basic understanding of circuits. Sorry.
  6. hevans1944

    hevans1944 Hop - AC8NS

    Jun 21, 2012
    Does not the original configuration already do that? You press the remote button and the bell "chimes". If you want to do more than that, you will have to "reverse engineer" the doorbell circuit, i.e., the "receiver" to intercept the signal that operates the bell (or whatever) and use that signal for your own purpose, perhaps toggling a latch each time the remote button is pressed. The latch would then operate the buzzer, turning the buzzer on when the latch is set and turning the buzzer off when the latch is reset. Do you have a link to a web page that offers the doorbell you are trying to use?

    You will need more than a basic understanding of circuits to do modifications successfully. An oscilloscope would be most helpful in identifying the signal you need to intercept. Several really inexpensive versions are available on the Internet, but many are kits that require skill to assemble successfully. You don't need anything fancy or with more than a few kilohertz of bandwidth. No need to observe the RF signals transmitted or received. Do you have any test equipment available?
    Bluejets likes this.
  7. Robertfhegreatnewb


    Apr 17, 2016
    I'm trying to make something that when you press the button it produces a continuous signal which makes the buzzer sound continuously then when it is released it stops. Any suggestions on how to do this

    I'm using a cheap china-made doorbell.
  8. Bluejets


    Oct 5, 2014
    Hevens has already covered this in his reply #6 above.
  9. 73's de Edd

    73's de Edd

    Aug 21, 2015

    Sir Robertfhegreatnewb. . . . . . .

    In response to your perceived and implied . . . . . .Say whaaaaaaaaaaaaaaaaat ? ? ? . . . from our Right Revered, Honorable and Esteemed . . . . . hevans1944 . . . aka . . . "the hopster".

    Let me initially give you some design parameter insights of those two paired units that you are hoping to use.

    Looking at the transmit board:

    At the very right top corner is the oscillator/transmit transistor . . . . . . .refrain from WANTING to straighten it up vertically . . . as it will probably snap a wire lead in the process.
    At the left is the 14 pin Pericom encoder/decoder IC which gives a coded digital modulating of your transmit signal. This way your unit will not be erroneously ringing a like branded doorbell of next door neighbor Tilly the Toiler , or Ivan the Terrible across the street or even 'ole Granny Goodknockers, a full two houses on down the street..
    Next item of interest is the metal "sardine can" at the end of the IC . . . . if it has 2 leads underneath it, it could be a crystal related to the time base / clock of the 14 pin IC . . . or you could find a 27 or 49 numbering sequence on its metal case. In that case, still being a crystal, but transmitter stability related.
    If it has 3 or 4 leads it will be a SWIF filter, related to the frequency stability of the transmit RF oscillator circuitry.
    Dropping down from the mentioned "can" will be seen, the foil side profile of the etched copper hairpin loop that is associated with the inductive element of the transmit tuned circuit and is also being the units transmit "antenna".
    With that info now known . . . . best that the unit now receive its outer housing . . . . . to space the circuit board out from the detrimental detuning / loading effect of having ones hand and fingers in CLOSE proximity or actual contact with the PCB proper.

    Moving down to the receiver board:

    Top left corner is the transistor (2S1815 ? ) that is the superregenerative rceiver of the transmitted signal.
    The transmitter generated a transmit frequency that was basically a bit coarse in its accuracy, while the receivers top left ORANGE coil with its internal, adjustable brass slug lets the receiver be precisely tuned to the transmitters frequency.
    The clutter of discrete support components and on board filtering between the receive transistor eventually presents an audio tone modulated signal to the input of the 14 pin decoder IC.
    If the coding handshake is in order, the chip then passes a DC control signal to the brown phenol "daughter" board that you see mounted vertically at the very end of the IC.
    Center, left side of that board is seen a black epoxy blob . . . .that is called a COB . . . Chip On Board . . . . it encapsulates / covers the integrated circuitry underneath it.
    That circuitry is taking a DC start signal and then triggering the start of the one shot sequence of creating the tone, voicing and amplification of the ensuing audio chime action to
    drive a piezo or PM speaker below.
    Its interconnection, probably being the two BLUE wires, due to their proximity and directional layout..
    That must leave the 2 yellow wires for power input ?
    At the right center of the board I'm rolling around in my head, if that is an adjustable micro volume control for the chime circuitry . . . or if being a" tact" momentary contact switch . . .and wondering its purpose / need ?

    Now, with you being minimally, "micro" educated for what you are looking for . . . . . .

    Sleuthing . . . . .

    Get the transmitter back to normal power up on both units and confirm a chime sequence activation, with the transmitter.

    Working with the receiver portion:
    Take a voltmeter with its negative lead connected to battery ground then use the other lead to stay at a random initial connection into the daughter board .
    You are looking for one, of those several incoming connections into the daughter board, that shows a voltage presence for the duration that the transmit button is held down and drops when the transmit button is released..
    Now sample all and see if you now can find one, or possibly others, among its series of connections that are coming into that daughter board.
    THEN . . . . a possibility of accomplishing what you wanted, is now being in sight.
    Question now . . . .does the chime seem to come from a small piezo-electric transducer or a conventional permanent magnet / coned speaker ?

    Need to know what components I can take out without damaging it.

    Hee . .hee . . .hee . . . . .If you are feeling a daunting . . .yet . . . unrelenting need of accomplishment . . . you just might go to the receive board and surgically extract the round cylindrical component between the IC and the daughter board . . . . it being of beige / black band / beige colorization and you replace it with a solid jumper wire..
    Then you tape that component onto your trophy board on the wall.

    Thasssit . . . . .

    73's de Edd

    Last edited: Apr 17, 2016
    hevans1944 likes this.
  10. hevans1944

    hevans1944 Hop - AC8NS

    Jun 21, 2012
    In other words, put it back together, batteries or whatever included, power both units up and press the doorbell button on the transmitter (the thingy you call remote). If the thingy you call the receiver makes a noise each time you press the button on the remote... congratulations! You apparently have not bricked these two devices yet.

    Now do as @73's de Edd instructed and probe around with a digital multi-meter (DMM) using its voltage function to find a signal that changes each time you press and hold the button on the remote. A DMM has two kinds of voltage functions: DC and AC. Try both and write down your results. Maybe annotate your images with what you find. If you find a signal that responds to your button presses, that's the signal you will use to (eventually) operate your buzzer. Report back here when you find it and Edd or someone else here will provide further instructions.
  11. Colin Mitchell

    Colin Mitchell

    Aug 31, 2014
    The only thing you can do is pick off the signal that goes to the speaker and use it to turn on a circuit for the duration of the tune.
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