DIYbanter - View Single Post

[email protected]

wrote:

Hi all, I want to convert a mains type digital daily/weekly timer to
12v (nom.) operation.I know that the cct. inside (relay) etc operates
at 28v, and normally could float at mains potential in normal use, this
conversion is required for use in a boat so no mains likely to be
present! if i change the relay to a 12v one, with proper protection
(fusing etc) where abouts in the cct could I disconnect the "mains
dropper" part and connect the battery 12v?is there a site containing
ccts that use mains dropping cap/res type ccts...with thanks,

you should succeed if the circuitry and relay will both function on
10.8v, which is what you can count on from lead acids. 10.8 on a 28v
relay is optimistic, you may need to use a voltage doubler first.

The mains voltage reducer is almost always a series CR, plus there will
be a diode and capacitor to turn the ac into dc.

Only thing to be a bit ware of is possible ground conflicts, as timer
and relay might just work in series on the original box. Unlikely but
possible.

NT