Thread: Voltage Sensing Switch?

Go to www.axminster.co.uk
In the catalogue page 1.107 youll find what youre looking for. Its very expensive however. Its called: Auto Extract Controller Unit
There was another unit launched here a couple of years ago that retailed for around £30 but I havent seen it advertised for some time now so dont know if its still available.
I will have a look at some of the back issues but cant promise anything as Ive got literally hundreds of the dam things, and Im still trying to find another article for someone.
beejay1

http://community.webshots.com/user/eunos9

Some time in the last few years, FWW had one (or 2?) articles on building your own auto voltage flow detector - it used a couple of coils around the active wire/s to trip a relay & turn on your dust sucker. I think it would be highly unlawful to attach one to a fixed installation here in Oz, but it may be OK if it is built into the middle of a power cord - I think there is something about cords & portable equipment being OK to DIY.

Of course you won't find me attaching such a thing with having it checked out by a real qualified electrician first - I don't want to leave a me-shaped dent in the tin shed wall from something going wrong!

Hi,
I have a FWW where it sets out how to build one of these electric current sensing devices for your exact workshop situation. It did not seem to be too expensive. I will look up the reference and post here for you.
Paul

In FWW July/August 2000 (No. 143) there is an article called "Dust Detector". The description says "Switch automatically turns on dust collector when machines are running". It features the details for both 110Volts and 220Volts (=Aust and NZ mains) circuits.

The heart of the circuit is a device called a "toroid current sensor" with a part reference of SSAC current sensor TSCHAA (see website www.ssac.com) that costs around US $38 (in 2000)
The article did suggest an alternative of a remote controlled switch for the dust collector using either a radio or infrared remote control. I think that there is such a remote switch available for lights in Aust.
Paul

Quote1 from a previous thread on dusty switching:

" Bob,

To walk out to turn DC on is tiresome and often when just doing one crosscut etc too much trouble so the DC system falls down.
I bought a contactor that has a coil voltage of 24 volts. I also bought a RF remote control unit from Alltronics which has a relay that switches. I have all this mounted in a mains box. The RF remote switches its own relay 'on' or 'off' and in turn swithches a heavier rated relay on or off which in turn pulls the contactor in or drop it out. It also works like a no voltage switch. So when i go into my shop I have a tiny remote around my neck and can switch the DC from anywhere . I was going to switch at the gates but besides far too much wiring and the possibility of dust in switches etc etc, I decided on the RF system. I cant remember the price of the contactor, but the RF unit with toggling relay was about $110 and the heavy relay about $10. The DC is hard wired. The RF unit comes with 2 remotes, so if I accidentally take one into the house and leave it there, then I still have another in the shed."

Quote 2:

"My cyclone and seperate chip seperator drum is outside the shed but under the awning. It is remotely switched on with a radio controlled phob ( like a car alarm phob ) and contactor box that I made up. This enables me to turn the DC on/off from anywhere in my shop."


I hope this helps you to make a decision. I find the above installation works really well.
Enjoy whats left of the weekend

I have one main objection to using current sensing for turning the DC on and off. The objection is mainly about the 'off' bit. The DC will stop at the same time as you stop the tool. If your dust lines are long this will probably mean that not all the dust will be cleared before the DC stops. If you use this approach do remember to put an override switch somewhere so that you can run the DC for the floor sweep etc.
Gatiep - although I have gone the 'switches on gates' approach I also like yours. Dust in the switches is easily solved by using reed switches and magnets as in burglar alarm fittings. The wiring isn't really a problem as being a 12v system it can use almost any old wire and it doesn't require a sparky.

Originally Posted by bsrlee

Some time in the last few years, FWW had one (or 2?) articles on building your own auto voltage flow detector - it used a couple of coils around the active wire/s to trip a relay & turn on your dust sucker. I think it would be highly unlawful to attach one to a fixed installation here in Oz, but it may be OK if it is built into the middle of a power cord - I think there is something about cords & portable equipment being OK to DIY.

Of course you won't find me attaching such a thing with having it checked out by a real qualified electrician first - I don't want to leave a me-shaped dent in the tin shed wall from something going wrong!

You can DIY on things with in the middle of power cords if you have a restricted electrical licence IIRC

Tom

I have not done it but I have seen a system that works very well using the remote control system from a remote control roller door minus the mechanical bits the bloke just carries the sending unit in his pocket and starts up the collector when ever m/c running or not.

Cheers Arch.

Originally Posted by GeoffS

I have one main objection to using current sensing for turning the DC on and off. The objection is mainly about the 'off' bit. The DC will stop at the same time as you stop the tool.

You can buy a relay with an "on" or "off" delay timer included (its the same relay, just configured differently). So when the power on your machine goes off the power to the DC unit doesn't go off until after the set delay period.

Qw

Like turbo timer in a car, jaycar some have kits that might be of help.

QldWoodie - good point but be warned, contactors are expensive, ones with delay functions are extremely expensive!
Harry72 - could be useful but kit gear is rarely designed for handling things like 1 to 3 hp motors. Mostly just 100w light bulbs.

All ideas are worth thinking about. It all depends on the individual circumstances.

Cheers

Well chaps the soundman has the answer.
After a question on this BB about a over year ago ( and my own desire to automate )I was prompted to begin development of such a device.

And such a device does now exist in my workshop. The prototype has been working on my bench and main extractor (and it is delightfull), the beta production run of printed circuit boards has been done & I have a couple of actual examples of the real device assembled.

The design takes into acount startup delay of the extractor so as to wait for the start current of the master machine to subside befor the slave is fired up and it runs on for a period after the master machine has been shut down.
Manual start & stop functions are provided and it runs fail safe on power failure. A variety of power supply configurations are considered and it will triger reliably form 100 watts up to very large currents.

I had hoped to have this device to market by now but I have been distracted by more immediate paying work.

It this stage I am about to have the device compliance tested, write the manuals & other documentation and front pannel art work.

The initial beta run will be of about 30 units ant the members of this BB will be the first to be offered the units.

I hope to have something for you in the next couple of months.
About 5 of the units are already promised.

thanks for you patience
cheers

Originally Posted by GeoffS

QldWoodie - good point but be warned, contactors are expensive, ones with delay functions are extremely expensive!
Harry72 - could be useful but kit gear is rarely designed for handling things like 1 to 3 hp motors. Mostly just 100w light bulbs.

All ideas are worth thinking about. It all depends on the individual circumstances.

Cheers

Yes true but it only has to trigger a relay... I think, Im not real sparky minded!

Hey Sman, do you have a approx costing yet, for say a 3hp dusty with 4-5 area's to be draughted/switched?

Sorry I havn't got back to this post for a while.
The requirements would seem reasonably simple on the surface. Yeah you just gota switch a relay!
First find your relay. Rated for motor start, at least 3Hp and costing less than an arm & a leg.
Current tripping? Well you need to trip on a small sander and equaly a 5Hp saw bench without false trips.
Then get the whole thing compliant with the regs.
The original proto was relatively easy (and its still going) but I couldn't sell it like that without getting my but fried by all & sundry.
Any way I'm trucking thru my work backlog & hope to get back to this project soon.
Cost is an interesting point.
I'm hoping to get the basic unit in for arroung the $300 mark.
But one of the "significant" parts of the cost is the plugs & sockets.
So when we start looking at 15amp & 20 amp versions (with less common plugs) the cost starts to rise a little. Start talking 3 phase & the plugs will be a major portion of the cost.
The view is to make the item a plug & socket, no sparky required item.
I'm still considering the regulatory & liability issues of supplying short form and hard wire versions.
This was and always will be considered an "industrial product" intended for the small workshop. As such it would not appeal to the " less serious" amateur wood worker.
Enough gum flappin for now. Thanks for your interest.