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?

 

Perhaps a mixer would help by isolating the chimes from each other.

A good sized capacitor will help reduce the buzzing.

 

hi,

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.

moz

 

Originally posted by mozikluv@Mar 13 2006, 11:37 PM
hi,

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.

moz

[post=14935]Quoted post[/post]​

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.