06-05-2015, 06:04 AM
(05-05-2015, 10:13 PM)Mark Hennessy Wrote: Which reminds me - without re-reading the whole thread, I don't think that anyone has mentioned an important detail about the power supply: if you take the 12VAC from the existing transformer and full-wave rectify it, you'll get about 16 to 18 volts DC, depending on how close to 12V the transformer actually is.
I was having a little problem with our door chimes, with the standard Friedland transformer they weren't loud enough, I measured the transformer which was a nominal 12VAC and as far as I can remember it was about 20VAC off load and about 8VAC with the bell push depressed, so I put a small bridge rectifier and a 220μF across the secondary and they work perfectly, just measured across the capacitor and it's 36V, so it's 'capacitor discharge chimes', they've been working like this for about 4 years.
John
