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