Automatically powering 220V dust vac when 220V saw starts

[David L. Jones]

On Nov 6, 7:27 am, "Dan" <n...@hotmail.com> wrote:

I have a 220 volt 13 amp table saw & a 220 volt 9 amp dust collector, the
latter of which vacuums up the saw dust from the former. I would like the
vac to start when I power up the table saw, & shut down after the saw shuts
down. Ideally, the vac would run 5 to 10 seconds after the saw shuts down.
I'm thinking I can control the vac with a solid state relay like this onehttp://www.allelectronics.com/cgi-bin/item/SRLY-21/500500/25_AMP_SOLI...
which has an 18 to 35 volt AC control voltage. It would be great if this
could be done with no wires from the saw to the vac. Anyone have any ideas
on circuits to sense when the saw powers up, maybe some sort of inductive
current sensor, as well as a means of relaying this wirelessly to a small AC
supply which would activate the relay? The wireless part might be
accomplished with thishttp://www.allelectronics.com/cgi-bin/item/RC-10/search/KEYCHAIN_REMO...
connected to a 12 volt relay which would power up a suitable ac supply.
It's an RF remote on-off switch. Turning on the saw would close the "on"
contacts (by some means) then after the saw shuts down, delay would take
place (by some means) after which the "off" contacts would be closed.

Or maybe there's a better approach?!?

TIA

Dan

You can get power boards that have switched outlets that only turn on
when the device plugged into the main outlet switches on. They are
designed for home theatre systems and computer systems etc.

Dave.

 

[ehsjr]

Dan wrote:

"ehsjr" <ehsjr@bellatlantic.net> wrote in message
newsbdYi.5837$Cc.350@trndny09...


If you don't want to modify the saw's wiring,


Thanks for the reply, great ideas. I'd probably forgo the cord/receptacle &
just tap into the saw's wiring.


For the delay, and the circuit to trigger the RF keychain
transmitter, you could use CAT# RLY-89 with a 3300 uF
50V cap in parallel with the coil. Feed it with 24V DC
and wire the contacts to the contacts of the keychain
transmitter, and it will delay the drop out of the vac
system ~10 seconds.


Makes sense.



You could wire up 2 of CAT# TX-4025
in series on the primary side and parallel on the secondary,
and use the voltage produced at the center tap and one of the
ends. Treating that as a single transformer in the diagram
below:

------- D1
|Xformer|CT---[330R]--->|---+---------+
| | | | ---o To RF
| | [3300uF] [RLY-89] ^--o Xmitter
| | | |
| |-------------------+---------+
-------


The 330 ohm resistor limits the surge current through
the cap when the switch is turned on, and lowers the
peak voltage so that cap gets charged to about 24 volts.
(Peak would otherwise be ~28 volts). When the switch
is turned off, the cap holds the relay energized while
it discharges for about 10 seconds. The relay contacts
operate the RF transmitter.

Ed


You kind of lost me on the last part, but I think basically, the 2 xformer
arrangement is simply a 24vdc half wave rectified power supply (using a
single diode), right?

Right. Since you have 240 vac input, the recommendation
was for 2 cheap 120 vac input xformers in parallel on the
primary side. On the secondary side, with the secondaries
wired in parallel (and in phase), the voltage from the
center tap to either end is 20 volts with the part
specified. With the components specified, the circuit
produces about 24 volts across the cap.

There is one confusing issue with the RF remote. The control appears to
work with 2 momentary contact buttons, push & release one to turn on, push &
release the other to turn off. So simply have a relay with closed contacts
during the entire "on" phase may not work to keep the unit on, and simply
opening that connection will not shut the unit off, nor would a SPDT
arrangement which kept one set of contacts closed when the relay is
energized, another closed when it's not. What I'd need is something to
briefly close one set of contacts when the saw powers up, then briefly close
another set after a delay when the saw is powered off.

Dan

Ok. For push and release for on, and push and release for
off, you need additional circuitry. Since you seem comfortable
using relays, we'll stick with them. Use the circuit above, but
change RLY-89 to RLY-481. You may want to add a 1000 or 2200 uF
cap in parallel with the 3300 uF cap, because RLY-481 will drop
sooner than RLY-89. The change to RLY-481 is needed to provide
SPDT contacts, because RLY-89 is SPST. (Allelectronics part #s)

With the new relay, add two more relays and two caps,
a diode and resistor, like this:

D2
+24 ---+--->|---+----------+
| | |
[RLY-481] [C2] |> |<------[RLY2]---+
| | | |
| +-[47K]-+---[C3]---[RLY3]---+
| | |
Gnd ---+--------+---------------------------+

As drawn, the relay contacts for RLY-481 are shown making
contact on the normally closed side, with no power applied.
When power is applied, RLY-481 energizes, its contacts transfer,
then C3 charges drawing current through RLY3 causing it to
energize.

When C3 is sufficiently charged, the current it draws drops below
the current needed by RLY3, so RLY3 drops out. With C3 at 470 uF,
RLY3 will energize and de-energize quickly. The open and common
contacts (not shown)of RLY3 are wired to the on button of the
remote.

While that is happening, C2 (1000uF) charges to ~24 volts and
stays there while power is on. When power is removed, the 481
relay stays energized while the 3300 uF cap in the previous
diagram discharges. When the 481 relay drops, the contacts transfer
to the normally closed position, and RLY2 energizes from the charge
stored in C2. (D2 prevents the charge on C2 from discharging through
the 481 relay.) The charge on C2 discharges through RLY2, so the
relay drops out. The open and common contacts (not shown) of RLY3
are wired to the off button on the remote.

The 47K resistor allows C3 to discharge when the power is off, so
that it is ready for the next on cycle.

Ed

>

 

[Dan]

"ehsjr" <ehsjr@bellatlantic.net> wrote in message
newsbdYi.5837$Cc.350@trndny09...

If you don't want to modify the saw's wiring,

Thanks for the reply, great ideas. I'd probably forgo the cord/receptacle &
just tap into the saw's wiring.

For the delay, and the circuit to trigger the RF keychain
transmitter, you could use CAT# RLY-89 with a 3300 uF
50V cap in parallel with the coil. Feed it with 24V DC
and wire the contacts to the contacts of the keychain
transmitter, and it will delay the drop out of the vac
system ~10 seconds.

Makes sense.

You could wire up 2 of CAT# TX-4025
in series on the primary side and parallel on the secondary,
and use the voltage produced at the center tap and one of the
ends. Treating that as a single transformer in the diagram
below:

------- D1
|Xformer|CT---[330R]--->|---+---------+
| | | | ---o To RF
| | [3300uF] [RLY-89] ^--o Xmitter
| | | |
| |-------------------+---------+
-------


The 330 ohm resistor limits the surge current through
the cap when the switch is turned on, and lowers the
peak voltage so that cap gets charged to about 24 volts.
(Peak would otherwise be ~28 volts). When the switch
is turned off, the cap holds the relay energized while
it discharges for about 10 seconds. The relay contacts
operate the RF transmitter.

Ed

You kind of lost me on the last part, but I think basically, the 2 xformer
arrangement is simply a 24vdc half wave rectified power supply (using a
single diode), right?

There is one confusing issue with the RF remote. The control appears to
work with 2 momentary contact buttons, push & release one to turn on, push &
release the other to turn off. So simply have a relay with closed contacts
during the entire "on" phase may not work to keep the unit on, and simply
opening that connection will not shut the unit off, nor would a SPDT
arrangement which kept one set of contacts closed when the relay is
energized, another closed when it's not. What I'd need is something to
briefly close one set of contacts when the saw powers up, then briefly close
another set after a delay when the saw is powered off.

Dan

 

[ehsjr]

Dan wrote:

I have a 220 volt 13 amp table saw & a 220 volt 9 amp dust collector, the
latter of which vacuums up the saw dust from the former. I would like the
vac to start when I power up the table saw, & shut down after the saw shuts
down. Ideally, the vac would run 5 to 10 seconds after the saw shuts down.
I'm thinking I can control the vac with a solid state relay like this one
http://www.allelectronics.com/cgi-bin/item/SRLY-21/500500/25_AMP_SOLID_STATE_RELAY_18-32_VAC_CONTROL_.html
which has an 18 to 35 volt AC control voltage. It would be great if this
could be done with no wires from the saw to the vac. Anyone have any ideas
on circuits to sense when the saw powers up, maybe some sort of inductive
current sensor, as well as a means of relaying this wirelessly to a small AC
supply which would activate the relay? The wireless part might be
accomplished with this
http://www.allelectronics.com/cgi-bin/item/RC-10/search/KEYCHAIN_REMOTE_CONTROL,_12VDC_6_AMP_.html
connected to a 12 volt relay which would power up a suitable ac supply.
It's an RF remote on-off switch. Turning on the saw would close the "on"
contacts (by some means) then after the saw shuts down, delay would take
place (by some means) after which the "off" contacts would be closed.

Or maybe there's a better approach?!?

TIA

Dan

If you don't want to modify the saw's wiring, install a
homemade extension cord with a junction box and receptacle
at the saw end. Wire a transformer in parallel with the
receptacle, and a switch in series between the power cord
and the receptacle. Leave the saw switch on, and control
power to the receptacle and transformer with the added
switch. The transformer can power whatever circuit you use
to control the vac.

Switch
||
-----
Mains =========|Recpt|===SawCord
-----
||
Xformer

For the delay, and the circuit to trigger the RF keychain
transmitter, you could use CAT# RLY-89 with a 3300 uF
50V cap in parallel with the coil. Feed it with 24V DC
and wire the contacts to the contacts of the keychain
transmitter, and it will delay the drop out of the vac
system ~10 seconds. You could wire up 2 of CAT# TX-4025
in series on the primary side and parallel on the secondary,
and use the voltage produced at the center tap and one of the
ends. Treating that as a single transformer in the diagram
below:

------- D1
|Xformer|CT---[330R]--->|---+---------+
| | | | ---o To RF
| | [3300uF] [RLY-89] ^--o Xmitter
| | | |
| |-------------------+---------+
-------


The 330 ohm resistor limits the surge current through
the cap when the switch is turned on, and lowers the
peak voltage so that cap gets charged to about 24 volts.
(Peak would otherwise be ~28 volts). When the switch
is turned off, the cap holds the relay energized while
it discharges for about 10 seconds. The relay contacts
operate the RF transmitter.

Ed

 

[Dan]

Thanks for the reply. I'll look over your site, thanks!

All the auto-switches of this type I have seen for sale so far, like this at
Woodcraft are for 120 volts:

http://www.woodcraft.com/family.aspx?FamilyID=5855

Sears used to sell one also, again, 120 volts.

There's also this remote control, $70 for the 220 version
http://woodcraft.com/family.aspx?familyid=5117

I could easily rig up one of these from 2 All Electronics bits, total cost
about $30, but I know from experience if it doesn't turn on by itself, half
the time I'll forget until after making a cut!

Dan


"steamer" <steamer@sonic.net> wrote in message
news:4730a991$0$14113$742ec2ed@news.sonic.net...

--There's a widget for sale at Woodcraft stores (and other places)
that gives you wireless control of your vacuum system. It's only $30 or
so;
howzabout keeping it simple? Oh, and for needless complexity check out my
system: http://www.nmpproducts.com/exhaust.htm

--
"Steamboat Ed" Haas : Whatever happened
Hacking the Trailing Edge! : to Andy Philbrick?
www.nmpproducts.com
---Decks a-wash in a sea of words---

 

[steamer]

--There's a widget for sale at Woodcraft stores (and other places)
that gives you wireless control of your vacuum system. It's only $30 or so;
howzabout keeping it simple? Oh, and for needless complexity check out my
system: http://www.nmpproducts.com/exhaust.htm

--
"Steamboat Ed" Haas : Whatever happened
Hacking the Trailing Edge! : to Andy Philbrick?
www.nmpproducts.com
---Decks a-wash in a sea of words---

 

[Dan]

I have a 220 volt 13 amp table saw & a 220 volt 9 amp dust collector, the
latter of which vacuums up the saw dust from the former. I would like the
vac to start when I power up the table saw, & shut down after the saw shuts
down. Ideally, the vac would run 5 to 10 seconds after the saw shuts down.
I'm thinking I can control the vac with a solid state relay like this one
http://www.allelectronics.com/cgi-bin/item/SRLY-21/500500/25_AMP_SOLID_STATE_RELAY_18-32_VAC_CONTROL_.html
which has an 18 to 35 volt AC control voltage. It would be great if this
could be done with no wires from the saw to the vac. Anyone have any ideas
on circuits to sense when the saw powers up, maybe some sort of inductive
current sensor, as well as a means of relaying this wirelessly to a small AC
supply which would activate the relay? The wireless part might be
accomplished with this
http://www.allelectronics.com/cgi-bin/item/RC-10/search/KEYCHAIN_REMOTE_CONTROL,_12VDC_6_AMP_.html
connected to a 12 volt relay which would power up a suitable ac supply.
It's an RF remote on-off switch. Turning on the saw would close the "on"
contacts (by some means) then after the saw shuts down, delay would take
place (by some means) after which the "off" contacts would be closed.

Or maybe there's a better approach?!?

TIA

Dan

 

[Dan]

"ehsjr" <ehsjr@bellatlantic.net> wrote in message
news:kSuYi.6325$Cc.1092@trndny09...

Dan wrote:
"ehsjr" <ehsjr@bellatlantic.net> wrote in message
Ok. For push and release for on, and push and release for
off, you need additional circuitry. Since you seem comfortable
using relays, we'll stick with them.

Thanks for the reply. I see what you mean, using RC circuits to time the
relays. I'm not averse to a solid state solitution, if it would be more
straight forward. I actually studied all this 20-odd years, and I've built
a ton of stuff, etching circuit boards, etc., just don't remember any of it,
unfortunately...

Dan

 

[Dan]

"David L. Jones" <altzone@gmail.com> wrote in message
news:1194501277.398866.244460@y27g2000pre.googlegroups.com...

You can get power boards that have switched outlets that only turn on
when the device plugged into the main outlet switches on. They are
designed for home theatre systems and computer systems etc.

Dave.

Not in 220, though.

Thanks for the reply.

Dan

 

[ehsjr]

ehsjr wrote:

Right. Since you have 240 vac input, the recommendation
was for 2 cheap 120 vac input xformers in parallel on the
^^^^^^^^

series

primary side. On the secondary side, with the secondaries
wired in parallel (and in phase), the voltage from the
center tap to either end is 20 volts with the part
specified.

 

[ehsjr]

Dan wrote:

"ehsjr" <ehsjr@bellatlantic.net> wrote in message
news:kSuYi.6325$Cc.1092@trndny09...

Dan wrote:

"ehsjr" <ehsjr@bellatlantic.net> wrote in message

Ok. For push and release for on, and push and release for
off, you need additional circuitry. Since you seem comfortable
using relays, we'll stick with them.


Thanks for the reply. I see what you mean, using RC circuits to time the
relays. I'm not averse to a solid state solitution, if it would be more
straight forward. I actually studied all this 20-odd years, and I've built
a ton of stuff, etching circuit boards, etc., just don't remember any of it,
unfortunately...

Dan

Ok. You can hack a 120V GFCI and trigger it with the
240 volts saw, provided your 240 volt branch circuit
includes the neutral. (The GFCI needs 120V to operate.)
The GFCI will operate a relay that operates the vac - no
need for the R/C remote.

Or you can use a CT (current transformer) feeding a
resistor, rectifier and filter cap to make a DC voltage
that is fed to an opto-coupler. The output side of
the coupler can operate a relay (with cap in parallel
for your turn-off delay) that operates the vac - again,
no need for the R/C stuff.

So - do you have a neutral? If so I can post the
schematic for the GFCI modification.

Ed
kludge.

 

[Dan]

"ehsjr" <ehsjr@bellatlantic.net> wrote in message
news:3ecZi.163$WM.136@trndny05...

Ok. You can hack a 120V GFCI and trigger it with the
240 volts saw, provided your 240 volt branch circuit
includes the neutral. (The GFCI needs 120V to operate.)
The GFCI will operate a relay that operates the vac - no
need for the R/C remote.

Or you can use a CT (current transformer) feeding a
resistor, rectifier and filter cap to make a DC voltage
that is fed to an opto-coupler. The output side of
the coupler can operate a relay (with cap in parallel
for your turn-off delay) that operates the vac - again,
no need for the R/C stuff.

So - do you have a neutral? If so I can post the
schematic for the GFCI modification.

Ed
kludge.

Ed-Yes, the outlet does have a neutral. Thanks for your continued input on
this!

Dan

 

[ehsjr]

Dan wrote:

"ehsjr" <ehsjr@bellatlantic.net> wrote in message
news:3ecZi.163$WM.136@trndny05...

Ok. You can hack a 120V GFCI and trigger it with the
240 volts saw, provided your 240 volt branch circuit
includes the neutral. (The GFCI needs 120V to operate.)
The GFCI will operate a relay that operates the vac - no
need for the R/C remote.

Or you can use a CT (current transformer) feeding a
resistor, rectifier and filter cap to make a DC voltage
that is fed to an opto-coupler. The output side of
the coupler can operate a relay (with cap in parallel
for your turn-off delay) that operates the vac - again,
no need for the R/C stuff.

So - do you have a neutral? If so I can post the
schematic for the GFCI modification.

Ed
kludge.


Ed-Yes, the outlet does have a neutral. Thanks for your continued input on
this!

Dan

Dan,

I can e-mail the full schematic to you, or post it on ABSE,
your choice. I'll describe the GFCI modification here. It
applies to a receptacle type GFCI using the LM1851 chip.

1) Remove the solenoid wires from the GFCI and replace it
with a 2.2K 1/2 watt resistor.
2) Remove the cathode lead of the SCR from ground.
3) Wire the cathode lead like this, adding the components
on the diagram:



AC Hot --------XXX--------------------+---+---+
| | |
--->|----+ | | |
\ | [180R] | |
G [1K] | | |
| MOC3031 | | [.01uF]
| ------ | | |
+--[3.3K]--[LED]---|1 6|--+ | [100R]
|+ | | | |
[4.7uF] | | [TRIAC] |
| | | / | |
+------------------|2 4|--+ +---+
| ------ |
Gnd [Relay]
|
AC Neutral-----YYY------------------------+


Not shown is the wiring from the gate (G in the diagram)
of the SCR to the LM1851 chip in the GFCI, the wiring
to the anode of the SCR, or the remainder of the GFCI
circuitry.

The lines marked XXX and YYY are connected to the LINE
hot and neutral of the GFCI. The hot LOAD side of the
GFCI is connected to your saw. The neutral LOAD side
is not used.

Wire the relay contacts to control your vac. Wire the saw
to the AC hot in the above diagram and the other AC hot lead.

As shown, there is no delay on dropout. To get that, wire
a transformer in place of the relay, use the secondary to
feed a DC supply, and use the relay and parallel cap
mentioned in the earlier post.

With the above wiring, when the saw is turned on, there is
an imbalance in the AC Hot and neutral currents. The GFCI
senses that, and turns the SCR on. (It turns off every time
the AC crosses zero, but is turned back on again by the GFCI
chip) Pulsating DC appears at the cathode, and is smoothed
by the 4.7 uF cap. That turns on the MOC3031 opto coupler,
which turns on the triac and powers the relay or transformer.
When the saw is off, there is no imbalance, so the GFCI does
not turn the SCR on.

Ed

 

[Dan]

"ehsjr" <ehsjr@bellatlantic.net> wrote in message
news:e8%Zi.3279$WM.2338@trndny05...

Dan,

I can e-mail the full schematic to you, or post it on ABSE

Ed-Posting it on ABSE would be great. Could you include the one for the
multi-relay circuit as well? Having a hard time making sense of the ASCII
schematics!

Thanks again Ed!

 

[JeffM]

Dan wrote:

Having a hard time making sense of the ASCII schematics!

Set your newsreader (or Outlook Express, if that's all you have)
to use a monospaced font:
http://groups.google.com/groups/search?q=mono-spaced+ASCII+Outlook-Express

or
Cut & paste into a monospaced text editor like Notepad.

or
Use Google's archive:
http://groups.google.com/group/sci.electronics.basics/msg/16dd2e36bfde79c9?dmode=source
http://groups.google.com/group/sci.electronics.basics/browse_frm/thread/b753562ea5ebcc6f/http://groups.google.com/group/sci.electronics.basics/browse_frm/thread/b753562ea5ebcc6f/16dd2e36bfde79c9?fwc=1

 

[ehsjr]

Dan wrote:

"ehsjr" <ehsjr@bellatlantic.net> wrote in message
news:e8%Zi.3279$WM.2338@trndny05...


Dan,

I can e-mail the full schematic to you, or post it on ABSE


Ed-Posting it on ABSE would be great. Could you include the one for the
multi-relay circuit as well? Having a hard time making sense of the ASCII
schematics!

Thanks again Ed!

I just posted the modified GFCI schematic on ABSE.
I don't have the multiple relay schematic as a jpg.

Ed

 

[Dan]

"JeffM" <jeffm_@email.com> wrote in message
news:1194916025.338924.313540@22g2000hsm.googlegroups.com...

Cut & paste into a monospaced text editor like Notepad.

Thanks Jeff, a major improvement!

Dan

 

[Dan]

"ehsjr" <ehsjr@bellatlantic.net> wrote in message
news:E4w_i.7978$ds.7969@trndny09...

I just posted the modified GFCI schematic on ABSE.
I don't have the multiple relay schematic as a jpg.

Ed

Got the schematic, thanks Ed!

Dan