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433MHz door bell - Tx antenna feed

Discussion in 'Radio and Wireless' started by Cirkit, Mar 17, 2018.

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  1. Cirkit

    Cirkit

    124
    10
    Oct 28, 2015
    I am trying to work out whether the component indicated by an arrow in the photo in the antenna feed, is a capacitor and what its value is likely to be?

    I have tried measuring it with a few different meters and it reads open circuit in resistance and capacitance mode which makes me think it might be faulty?

    I think the component above connected to the antenna is an inductor and measures around 0.47Ω.

    The door bell is functioning intermittently when the receiver batteries start to get a little low so I'm wondering whether the reduced transmission power may be causing the intermittent operation?
     

    Attached Files:

  2. davenn

    davenn Moderator

    13,654
    1,888
    Sep 5, 2009
    yes most likely a cap probably around 10 - 30 pF range


    It should

    you cap meter may not be able to read that low


    yes, looks like an inductor


    I strongly doubt that that capacitor is the problem


    A better pic would have been good, that one supplied is VERY blurry


    Dave
     
  3. kellys_eye

    kellys_eye

    4,275
    1,146
    Jun 25, 2010
    The receiver batteries? Wouldn't the 'fault' be with the receiver part then, rather than the push-button (transmitter)?
     
    davenn likes this.
  4. hevans1944

    hevans1944 Hop - AC8NS

    4,536
    2,112
    Jun 21, 2012
    Hmmm. Fuzzy picture seems to go well with the fuzzy logic. Check the batteries on the transmitter for fuzz too.

    Earlier this week, while we were looking for something (I forget what) in our garage, my wife pulled a couple of AA cells out of a box we had packed for our move to Florida last year and asked if the fuzzy cells she held out to me should be thrown away. Well, duh! Fortunately the icky cells were in a plastic baggy, so whatever the leaky fuzzy stuff is, it didn't affect anything. These were standard alkaline cells, so safe to dispose with household trash, which I did.

    As far as @Cirkit's problem is concerned: check the batteries and their contacts to make sure everything is clean, with no traces of corrosion. Make sure the batteries are fresh (check date code) and their open-circuit terminal voltage is up to snuff... if this wireless doorbell was working satisfactorily in the past but is now intermittent, the problem is likely a dirty switch contact, a dirty battery contact, or an almost depleted battery.
     
    SUBSTATION likes this.
  5. FuZZ1L0G1C

    FuZZ1L0G1C

    368
    117
    Mar 25, 2014
    Hi Cirkit.
    If you have a flatbed scanner, or access to one, scanning the board placed directly on the glass gives quite a clear image, as long as there aren't any larger components, as SMD component faces should be at focal point (glass surface).
     
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