Updating of our old Westminister door chimes


New Member
Hi ... I recently updated our 45 year old Nutone Westminister Door Chimes
> as the mechanical end of it was giving problems. So I updated it using a
> PICAX 08M2 I also put a PICAXE MP3 board in it so we could hear the chimes
> played electronically down in the family room over a speaker. The unit seams
> to work well, except about once every couple of weeks it will go through
> one complete cycle but the MP3 board will not play as the front door
> button has not been pushed as that is the only way that the board can be tripped.
> Now the system till trip it's self some times during a sever thunder storm
> ,& that I expect. Does anyone out there have any idea why this is happening. I can send
> you the code and a schematic of this project if you like. Thanks any help
> would be appreciated. Doug Gale
Attached Thumbnails Attached Thumbnails
Click image for larger version.



Senior Member
Nice project. Perhaps the long wires to your doorbell are acting like an antenna and picking up RFI. One goes to ground and one to Picaxe input C.3? You can try a filter capacitor from pin C.3 to ground, anywhere from 0.1 to 1.0 uF (watch polarity on electrolytics).

Did you put flyback diodes on your chime solenoids?


New Member
Hi Erco ...Thanks for you reply. I thought about that so I put two 1N4148 diodes on C3 thinking that may be better, but I could try the capacitor on it as well, & yes I did put 1N4004 diodes across each chime solenoid & there is also a clamping diode inside each MOSFET. So i'll have to pull the unit off the wall & try your idea. Thanks again. Doug VE3DSA