Electronic Door Chimes

Discussion in 'The Projects Forum' started by GFord, Mar 13, 2006.

  1. GFord

    Thread Starter New Member

    Mar 13, 2006
    I have four Heath/Zenith electronic door chimes (the kind that can be set to eighty or so different songs) that I grouped into a common output speaker bus and amplified to be heard in seven remote speakers. Note the attachment I included with this message. The problem is that while it works for a short while one or more of the chimes will stop working and must be replaced. All I can figure is that the back feed of the output from one chime is damaging the other chimes. Is this a likely cause? If so then how can I prevent it?
    Also, even if only one chime is hooked up to the amplifier I get a constant background hum on the remote speakers if the volume is turned up enough to actually be of use. Is there a way to filter out this background noise?
  2. thingmaker3

    Retired Moderator

    May 16, 2005
    Perhaps a mixer would help by isolating the chimes from each other.

    A good sized capacitor will help reduce the buzzing.
  3. mozikluv

    AAC Fanatic!

    Jan 22, 2004

    buying a simple mixer will do but if you want to build it, then 2 pcs. of quad op amp to act as your buffer stage and a dual op-amp to act as your pre-amp.

    you did not mention the capacitance value of your power supply filter. but a 2200uf electro cap will usually cure that humming. if it does not cure it, then something else is wrong.

  4. windoze killa

    AAC Fanatic!

    Feb 23, 2006
    Could also do this using passive resistive mixing. Don't ask me the values as it has been a very long time since I had to work that out.

    It has also been an even longer time since I have heard of Heath/Zenith. Must be 20 years.