Hi,

I am looking for some proper dusk dawn time switches such as the Sangamo
range, what are the proper prices and suppliers rather than Farnell?

Thanks

In article ,
James Salisbury nntp.dsl.pipex.com writes:
Hi,

I am looking for some proper dusk dawn time switches such as the Sangamo
range, what are the proper prices and suppliers rather than Farnell?

Any reason you want timed ones rather than photocell operation?

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In article ,
James Salisbury nntp.dsl.pipex.com wrote:
I am looking for some proper dusk dawn time switches such as the Sangamo
range, what are the proper prices and suppliers rather than Farnell?

Mechanical solar day switches have always cost an arm and a leg. Any
reason not to use a light sensing one?

--
*Beauty is in the eye of the beer holder...

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:
In article ,
James Salisbury nntp.dsl.pipex.com wrote:
I am looking for some proper dusk dawn time switches such as the Sangamo
range, what are the proper prices and suppliers rather than Farnell?

Mechanical solar day switches have always cost an arm and a leg. Any
reason not to use a light sensing one?

The building is currently wired with timers, I suspect they are standard
24hr rather than dusk dawn, wanted to do a cost benefit calculation.

In article ,
James Salisbury nntp.dsl.pipex.com writes:
Dave Plowman (News) wrote:
In article ,
James Salisbury nntp.dsl.pipex.com wrote:
I am looking for some proper dusk dawn time switches such as the Sangamo
range, what are the proper prices and suppliers rather than Farnell?

Mechanical solar day switches have always cost an arm and a leg. Any
reason not to use a light sensing one?

The building is currently wired with timers, I suspect they are standard
24hr rather than dusk dawn, wanted to do a cost benefit calculation.

Photocells are likely to be very much cheaper. They tell you
when it gets dark, rather than telling you what time sunrise/set is.
They don't go out of sync after a power cut (although clocks typically
have 24h spring reserve backup). They allow for different areas of a
building getting dark at different times. They are available for
switching at different lux levels.

OTOH, the dusk/dawn timers were available second-hand some 30+ years
ago as large numbers were stripped out of streetlamps. Places like
Proops, J Bull Electrical, The Shop on the Bridge (Reading), etc had
loads of them (and might still be worth trying). They still weren't
cheap though. They are a marvel of clockwork engineering if you get
the opportunity to play with one.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In article ,
Owain writes:
James Salisbury wrote:
The building is currently wired with timers, I suspect they are standard
24hr rather than dusk dawn, wanted to do a cost benefit calculation.

Sangamo timer £116 + VAT
http://www.tlc-direct.co.uk/Products/SGQ550.html

The picture is of the wrong item (a standard 2 on, 2 off timeswitch).
http://www.sangamo.co.uk/nmsruntime/...sID=2100003625
is the dusk to dawn version of it. Note that you should in theory use
different dials at different latitude (2nd page shows there are 4 dials
covering the UK latitudes). Using the wrong one will simply mean the
light over or under shoots dusk by some minutes on either side.

Oh, and I just found the instructions for it...
http://www.tlc-direct.co.uk/Technica...o/s250Q500.pdf

No offence to clockwork, but they date from an era when skilled labour
was cheap and a man on a bicycle checked the streetlights every six months.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

"Andrew Gabriel" wrote in message
...
In article ,
Owain writes:
James Salisbury wrote:
The building is currently wired with timers, I suspect they are standard
24hr rather than dusk dawn, wanted to do a cost benefit calculation.

Sangamo timer £116 + VAT
http://www.tlc-direct.co.uk/Products/SGQ550.html

The picture is of the wrong item (a standard 2 on, 2 off timeswitch).
http://www.sangamo.co.uk/nmsruntime/...sID=2100003625
is the dusk to dawn version of it. Note that you should in theory use
different dials at different latitude (2nd page shows there are 4 dials
covering the UK latitudes). Using the wrong one will simply mean the
light over or under shoots dusk by some minutes on either side.

I like the way it says it can be left unattended for years.. then states an
accuracy of 5 mins per year.
How far out does it need to be before it needs attending to?

"Owain" wrote in message
et...
dennis@home wrote:
I like the way it says it can be left unattended for years.. then states
an accuracy of 5 mins per year.
How far out does it need to be before it needs attending to?

If it loses 5 mins in the first year then gains 5 mins in the second and
third years, then loses 5 mins in the fourth year, it'll never be more
than 5 mins out.

That's a big if.

In article ,
Owain wrote:
dennis@home wrote:
I like the way it says it can be left unattended for years.. then
states an accuracy of 5 mins per year. How far out does it need to be
before it needs attending to?

If it loses 5 mins in the first year then gains 5 mins in the second and
third years, then loses 5 mins in the fourth year, it'll never be more
than 5 mins out.

That's probably a lot less than the natural variation of twilight due to
local weather conditions .

I'd imagine it uses a synchronous motor so isn't actually losing time. It
just can't adjust for the variations of the solar cycle year on year.

Owain

--
*A bicycle can't stand alone because it's two tyred.*

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
Owain wrote:
dennis@home wrote:
I like the way it says it can be left unattended for years.. then
states an accuracy of 5 mins per year. How far out does it need to be
before it needs attending to?

If it loses 5 mins in the first year then gains 5 mins in the second and
third years, then loses 5 mins in the fourth year, it'll never be more
than 5 mins out.

That's probably a lot less than the natural variation of twilight due to
local weather conditions .

I'd imagine it uses a synchronous motor so isn't actually losing time. It
just can't adjust for the variations of the solar cycle year on year.

That makes it worse doesn't it?


Anyway toolstation item #44224 looks like a simple solution.
LE buld with built in dusk to dawn sensor so you throw it away with the
lamp.