"mains " timer conversion...

[[email protected]]

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,

 

[N Cook]

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,

Does it either have a geared down motor to drive the on/off time select keys
on a dial or a LCD display?
Either of which may use an aspect of the AC supply

 

[[email protected]]

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

 

[Homer J Simpson]

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 are in the UK? Doesn't this device need 50 Hz for timing?

 

[James Sweet]

You are in the UK? Doesn't this device need 50 Hz for timing?

Some do, some digital ones use batteries as the sole power source for
the electronics though.

 

[Homer J Simpson]

Some do, some digital ones use batteries as the sole power source for the
electronics though.

OP said 'Mains' unit, implying UK and AC.

 

[John G]

OP said 'Mains' unit, implying UK and AC.

I have a mains powered timer in Aus (230v 50hz) which has an internal
battery and keeps time without the mains so the electronics does not
require 50hz.
Relay operation may another thing, I have never tried to see if it would
operate without the mains available.

 

[Homer J Simpson]

I have a mains powered timer in Aus (230v 50hz) which has an internal
battery and keeps time without the mains so the electronics does not
require 50hz.
Relay operation may another thing, I have never tried to see if it would
operate without the mains available.

I assume you know there are a bunch of electronics distributors in Sydney
and Melbourne who may have a 12 VDC unit you can use? Maybe even Dick Smith
or Tandy?

 

[John G]

I assume you know there are a bunch of electronics distributors in
Sydney and Melbourne who may have a 12 VDC unit you can use? Maybe
even Dick Smith or Tandy?

I suppose this reply should have been directed to the OP who someone
else decided actually lives in the UK.

I have been in electronics for 50 years in Sydney and in recent years
Dick smith has absorbed Tandy.

 

[Franc Zabkar]

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,

Can you see any zener diodes? My LCD, battery backed, digital timer
uses one for voltage reduction.

- Franc Zabkar

 

[kontiki]

Can you see any zener diodes? My LCD, battery backed, digital timer
uses one for voltage reduction.

- Franc Zabkar

Sorry for the delay in replying...thank you for all your suggestions
the timer is an LCD type (with backup lithium cell) ,the reason I am
using this (on boat) is because of its programmability, i.e. multiple
switching many times daily/weekly....not so sure a "simple 12v off the
shelf timer would do this, possibly NASA produces this sort of thing
way out of budget!..because it is battery powered and has quite low
standby power requirements it would be suitable for an unattended boat
(on water!).I would use it to "transmit short range" FM signals (ie
battery volts ,bilge water level,intrusion,etc.)to a reciever in my
car!This may sound a bit "over the top" but cant see a reason why
not.....thinking about the idea of using an old prepay mobile phone as
a burglar/intrusion alarm simple solenoid to press call
button....hmmmm?...perhaps two calls in two minutes to signify bilge
water alarm,,,three calls to indicate ..well its unending!
I think I really should get stuck in to these PICS. . .these I assume
would control all this?
I will persevere with the digital timer effort,thank you all again for
your input,sorry to so longwinded!any comments appreciated....
PS I hope I put this reply in the right place?