I share this with the group in case the conclusion (wire the bells in series, not parallel) is useful to anyone, and to see if anyone has any better advice about all this! And whether to use a snubber or not...
I tried to follow this...
One push, one transformer, two ding-dong bells in parallel. push:
I though a switched mode DC PSU could solve both problems, so tried to figure out what to buy...
The bells were rated 8-16V. 9V batteries or 16V transformer were suggested on the packaging, 1A load. I was quite surprised they'd worked in parallel from the 12V 1A transformer, but they seemed fairly happy with it.
I referred to the FAQ, and saw that I needed plenty of voltage and current. Taking all things into consideration, I chose this...
Long story short, it does this:
1) one bell - works, but with such force that the initial "ding" is more like a "BANG" that's going to shoot the sounder through the wall 2) two bells in parallel - holding the door bell push in (i.e. you'd just expect a "Ding"), you get a ding ... dong-ding ... dong-ding ... etc. Seems the PSU has some sort of short-circuit or overload protection that kicks in. 3) two bells in series - fine.So, that was the solution: put the bells in series. Works fine, but I'm wondering if a lower powered PSU with the bells in parallel might have been a better solution, or worse?
Also, for just one bell, when using a switched mode PSU, it seems you need far less voltage (or current) than the packaging or FAQ would suggest. Not that I've tried it - but with 15V 1.25A, I don't think the bell is going to last long, and while it lasts, it won't make a very nice "Ding"!
In all cases, the crackle in the door bell push itself is quite considerable. I could try a snubber, but I'm worried that's just going to draw a little current 24/7 - the whole point of the switched mode PSU is that it draws basically nothing when there's no load (i.e.
99.9999% of the time).Skinflint that I am, I'm trying to do the mental calculation of the cost of replacing the door bell push when it's prematurely worn out due to the arcing, vs the cost of the current drawn by a snubber. But I can't begin to figure it out!
Cheers, David.