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Vacuum Cleaner Power Take Off

Can any one advise me where I can find a circuit diagram for the power
take off sockets as fitted to some vacuum cleaners, so that they switch
on automatically when a power tool plugged in to the PTO socket is
switched on? I would like to build a unit to fit to an existing vacuum
cleaner used as a dust extractor for a circular saw, rather than buy a
new vacuum cleaner with power take off built in.
 
Can any one advise me where I can find a circuit diagram for the power
take off sockets as fitted to some vacuum cleaners, so that they switch
on automatically when a power tool plugged in to the PTO socket is
switched on? I would like to build a unit to fit to an existing vacuum
cleaner used as a dust extractor for a circular saw, rather than buy a
new vacuum cleaner with power take off built in.

So what you really want is for the vac to turn on when the saw comes
on?
Something like this?

http://sound.westhost.com/project79.htm

I doubt the PTO socket on the vacuum is intended for a load like the
saw. If it was, wouln't it just have an Edison socket to plug in the
controlling device rather than a proprietary socket?

GG
 
E

ehsjr

Jan 1, 1970
0
So what you really want is for the vac to turn on when the saw comes
on?
Something like this?

http://sound.westhost.com/project79.htm

I doubt the PTO socket on the vacuum is intended for a load like the
saw. If it was, wouln't it just have an Edison socket to plug in the
controlling device rather than a proprietary socket?

GG

That circuit is not suitable for the application. It introduces
a voltage drop to the saw, which is something you do not want.

Better off to use a toroidal current transformer, and a
different circuit, or buy a pre-made unit.

I made my own, by modifying a GFCI receptacle circuit. These
are the steps that need to be taken: You need to replace the
solenoid from the GFCI with a 2.2K resistor, and wire the GFCI
in the circuit such that it will trip when the saw is turned
on. (Wire the hot wire to the line side, and the neutral wire
to the load side. The saw plugs in to the receptacle.)

Normally, the solenoid is activated by an SCR in the GFCI.
With the modification you take the output of the SCR to a 4.7uF
250V filter cap through a 1K resistor. (The other side of the
cap is grounded.) From cap + , through 3.2K to an optoisolator
(I used an MOC3031, and I also put a LED in series as an
indicator) to ground.

The output of the optoisolator drives a standard triac circuit,
which can be used to operate a 110 vac relay. There are at
least two different GFCI circuits used in GFCI receptacles -
the one I modified uses the LM1851 chip.
http://cache.national.com/ds/LM/LM1851.pdf

In my case, I did not use the CT that is built in to the
GFCI, as I was putting the circuit into a smaller space,
and not using the GFCI receptacle - just the circuit.

I can post a jpeg on abse if anyone wants it.

Ed
 
R

Rich Grise

Jan 1, 1970
0
Can any one advise me where I can find a circuit diagram for the power
take off sockets as fitted to some vacuum cleaners, so that they switch
on automatically when a power tool plugged in to the PTO socket is
switched on? I would like to build a unit to fit to an existing vacuum
cleaner used as a dust extractor for a circular saw, rather than buy a
new vacuum cleaner with power take off built in.

Why not just run them both off one switch. Get an outlet box, and a switch
that's rated for the total startup current of both simultaneously, and a
duplex outlet. Plug the saw and vacuum into the duplex outlet, and leave
their switches on. Be sure that it's fused sufficiently, too.

Have Fun!
Rich
 
The whole idea, was to be able to connect several appliances to one
power circuit running through the PTO so that when any of the
appliances was switched on, the vacuum cleaner/dust extractor would
automatically switch on too. I realise that only one appliance could be
run at any time with the vacuum cleaner as the power supply to the
workshop is only rated at max 3200w (230v UK supply)
 
Max rated output of PTO on the machine I have looked at is 1800w which
with the 1000w of the vacuum cleaner, just leaves enough reserve for
the workshop lights, as the total power supply to the workshop is
3200w.

Thanks for your reply.
 
R

Rich Grise

Jan 1, 1970
0
The whole idea, was to be able to connect several appliances to one
power circuit running through the PTO so that when any of the
appliances was switched on, the vacuum cleaner/dust extractor would
automatically switch on too. I realise that only one appliance could be
run at any time with the vacuum cleaner as the power supply to the
workshop is only rated at max 3200w (230v UK supply)

Oh, then a current transformer at the input end of a power strip, and
the logic for it. :)

Good Luck!
Rich
 
J

Jasen Betts

Jan 1, 1970
0
Why not just run them both off one switch. Get an outlet box, and a switch
that's rated for the total startup current of both simultaneously, and a
duplex outlet. Plug the saw and vacuum into the duplex outlet, and leave
their switches on. Be sure that it's fused sufficiently, too.

practical for a bench saw or panel saw, but perhaps a little inconvenent for
a drop saw or a hand-held circular saw (which are typically switched bya a
trigger in the handle.

Bye.
Jasen
 
K

Ken Moffett

Jan 1, 1970
0
[email protected] wrote in @j33g2000cwa.googlegroups.com:
Can any one advise me where I can find a circuit diagram for the power
take off sockets as fitted to some vacuum cleaners, so that they switch
on automatically when a power tool plugged in to the PTO socket is
switched on? I would like to build a unit to fit to an existing vacuum
cleaner used as a dust extractor for a circular saw, rather than buy a
new vacuum cleaner with power take off built in.

I did this for the table saw in my shop. The sense section was a homebrew
current transformer made from a 110vac-24vac, E-I core, parallel bobbin
transformer with the secondary removed and replaced with a few turns of the
hot wire from the table saw circuit. On the vacuum side I did a delay-on-ON
so the saw and vacuum didn't start similtaniously (very high current draw).
Also, a delay-on-OFF circuit so that the vacuum continued for a several
seconds after the saw was shut off.

The circuit diagram is on my computer at work, so I'll pull it off tomorrow
and post it.

Ken
 
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