I have a conservatory with electrically operated roof vents and
electric ceiling fans. I would like the fans to operate automatically
when the roof vents are open. Power is supplied to the vents only for
30 seconds during opening or closing.

Using a couple of relays I could build a circuit that latches on when
the vents are opening, and unlatches when they are closing, but I'm
not confident I could design and build something safe and robust to
switch 240v . Unless there's something off the shelf that would do the
job?

Alternatively I could install a push-to-break switch at the vent,
would something like RS part number 456-4615 be appropriate?

Any other ideas?

Thanks

Tonkski

On 8 May 2007 12:46:50 -0700, tonkski mused:

I have a conservatory with electrically operated roof vents and
electric ceiling fans. I would like the fans to operate automatically
when the roof vents are open. Power is supplied to the vents only for
30 seconds during opening or closing.

I can think of a few ways but this bit stopped me actualy bothering to
list any.

but I'm
not confident I could design and build something safe and robust to
switch 240v .

Leave it, just get someone else to do it.
--
Regards,
Stuart.

"tonkski" wrote in message
ups.com...
I have a conservatory with electrically operated roof vents and
electric ceiling fans. I would like the fans to operate automatically
when the roof vents are open. Power is supplied to the vents only for
30 seconds during opening or closing.

Using a couple of relays I could build a circuit that latches on when
the vents are opening, and unlatches when they are closing, but I'm
not confident I could design and build something safe and robust to
switch 240v . Unless there's something off the shelf that would do the
job?

Alternatively I could install a push-to-break switch at the vent,
would something like RS part number 456-4615 be appropriate?

Any other ideas?

Thanks

Tonkski

That switch looks simpler than a latched relay solution, unless you can
somehow hook into one of the limit switch on the vent.
No doubt you'd also get the cover for it - can you mount it out of rain?
Phil

On 9 May, 12:06, "Phil B" wrote:
"tonkski" wrote in message

ups.com...



I have a conservatory with electrically operated roof vents and
electric ceiling fans. I would like the fans to operate automatically
when the roof vents are open. Power is supplied to the vents only for
30 seconds during opening or closing.

Using a couple of relays I could build a circuit that latches on when
the vents are opening, and unlatches when they are closing, but I'm
not confident I could design and build something safe and robust to
switch 240v . Unless there's something off the shelf that would do the
job?

Alternatively I could install a push-to-break switch at the vent,
would something like RS part number 456-4615 be appropriate?

Any other ideas?

Thanks

Tonkski

That switch looks simpler than a latched relay solution, unless you can
somehow hook into one of the limit switch on the vent.
No doubt you'd also get the cover for it - can you mount it out of rain?
Phil- Hide quoted text -

- Show quoted text -

Presumably though, you'd still use a relay and a low-voltage/isolated
"signal" current for the switch, as a safety precaution in case of
water contamination ?

On 8 May, 20:46, tonkski wrote:
I have a conservatory with electrically operated roof vents and
electric ceiling fans. I would like the fans to operate automatically
when the roof vents are open. Power is supplied to the vents only for
30 seconds during opening or closing.

Using a couple of relays I could build a circuit that latches on when
the vents are opening, and unlatches when they are closing, but I'm
not confident I could design and build something safe and robust to
switch 240v . Unless there's something off the shelf that would do the
job?

Alternatively I could install a push-to-break switch at the vent,
would something like RS part number 456-4615 be appropriate?

Any other ideas?

Thanks

Tonkski

Maybe an optical solution ? I'm sure you can get a sensor which will
switch a relay when darkened.

On May 9, 1:46 pm, Jethro wrote:
On 9 May, 12:06, "Phil B" wrote:

Presumably though, you'd still use a relay and a low-voltage/isolated
"signal" current for the switch, as a safety precaution in case of
water contamination

I like the sound of that. Can anyone suggest an appropriate step-down
transformer please?

On 9 May, 16:35, tonkski wrote:
On May 9, 1:46 pm, Jethro wrote:

On 9 May, 12:06, "Phil B" wrote:

Presumably though, you'd still use a relay and a low-voltage/isolated
"signal" current for the switch, as a safety precaution in case of
water contamination

I like the sound of that. Can anyone suggest an appropriate step-down
transformer please?

Maybe a doorbell one ?