# Extractor auto-switching...



## matt (19 Apr 2010)

Seems to me manufacturers are charging quite a lot for auto-switching on of extractors in exchange for what amounts to an extension lead with, at most, a couple of outlets...

Don't suppose the more electrically savvy around here have devised a way of automating extraction based on an entire collection of sockets around the shop? I'm thinking something between the extractor socket and specific circuit/s on the CU that senses demand and powers up the extractor socket.

?


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## 9fingers (19 Apr 2010)

I hope this post does not cause any offence to anyone.

It is quite straight forward for as you say the electrically savvy.

You need a current transformer to sense the load with a secondary controlling a sensitive relay that in turn drives a contactor that is man enough to turn on the extractor.

With more circuitry is is possible to keep the extractor running for a delay after the machine switches off to pick the last bits.

I have deliberately worded this in technical terms for those who understand, they are also likely to be able to wire everything in safely. If I were to give chapter and verse here, my concern is that some may become over confident and do themselves some damage.

For most people, either a remote controlled socket or a pull switch with a length of taught string running the length of the workshop, make a simple safe, easy to implement solution.

Bob


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## wizer (19 Apr 2010)

WellsWood has a genius solution to this problem:

https://www.ukworkshop.co.uk/forums/remo ... 26255.html


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## matt (19 Apr 2010)

Remote control switch was my first thought and pull switch my second. However, both mean I have to remember to do something  and the former requires a battery (trivial I know but I seem to spend my life changing batteries...)

However, I take your point about the risks involved in messing with wiring. I'm happy with normal wiring (as is a couple of electricians - one or other always validate what I'm doing as I never assume).

Neat solution with the blast gates - only problem is I've not got any  . (I was also fleetingly bothered by electric -> sparks -> dust :shock: (but suspect the risk is non-existent looking at the photos (unless, of course, you have metal ducting?

9fingers - don't suppose you happen to know roughly the cost of the components to make such a thing - including a time delay? (By rough I mean which side of £50 bearing in mind RPower's one is £130 for the extension lead solution).


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## 9fingers (19 Apr 2010)

Under £50 especially if your DC already has a contactor (nvr) fitted.
I made my current transformer out of an old blown up voltage transformer. Not difficult. Just keep adding turns until the relay works and then add a few more to be sure.
The primary is just a single pass through the core with the live wire in you CU.
Just need to make sure that it is not too sensitive so that the blower comes on when you switch the lights on!!

Bob


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## matt (19 Apr 2010)

Hmmmm... Food for thought. Many thanks.


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## scholar (19 Apr 2010)

matt":3hnin0aa said:


> Don't suppose the more electrically savvy around here have devised a way of automating extraction based on an entire collection of sockets around the shop? I'm thinking something between the extractor socket and specific circuit/s on the CU that senses demand and powers up the extractor socket.
> 
> ?



This is effectively what I have done with the setup shown here
http://i770.photobucket.com/albums/xx34 ... ctrics.jpg
This uses a Scheppach auto switch into which I connected an extra cable which runs to the commando socket outlets, such that 4 machines each will auto switch the extractor. You could extend this to any number of sockets, although it is only designed to run one machine at a time.

I am no electrical expert so building an auto switch would be beyond me - I recall that this auto switch cost me around £80 many years ago.

Cheers


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## ondablade (20 Apr 2010)

Felder UK offer several options of this sort from their web shop under dust extraction/dust extraction accessories/automatic start. felder shop (probably won't link right to the page as it seems to go to the top level page for some reason) 

Single machine up to multi channel units with blast gate switching. Not the cheapest, but the transformer coils sold separately are not expensive and might be a basis for something???


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## shingwell (20 Apr 2010)

I bought a little device from a charity shop for 50p made by the power company EON.

It's meant for computers so that when you turn the computer off, the device turns your printer, speakers, monitor etc off automatically. You plug the computer into the "master" socket and the other devices into the "slave" sockets.

However I have it rigged up with 4-way socket strips connected to the "master" and the dust extractor connected to the "slave", and the various machines plugged into the 4-way socket strips. Thus whenever any of the machines is turned on, so is the dust extractor. There's even a handy 5 second delay in turning the extractor off.

Here it is: http://www.eonenergy.com/At-Home/Go...Resource-Centre/resource-centre-powerdown.htm


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## Yetty (20 Apr 2010)

Check out the power saver type plugs, as mentioned by previous poster.

I've use a 'DSK1005 Intelliplug' from OneClick to switch on the bench vac.
http://www.oneclickpower.com/store/gbu0-prodshow/DSK105.html

Mine is used mainly for hand routers, rail saw, orbital sander.
The switch-on delay is roughly 4 seconds and it is £15 well spent.

Here's a picture. Tool in the top socket, vac in the side socket.






Hope that helps,


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