Switching AC loads
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Posts: 46,084
Hi All,
I need to be able to switch an AC load on/off with my Stamp but am
looking for alternatives to expensive, failure prone power relays, I
can do it with a relay if I must. I've never tried switching AC with
a power MOSFET before (just DC), can it be done? What other options
are there? Thanks.
-Dave
I need to be able to switch an AC load on/off with my Stamp but am
looking for alternatives to expensive, failure prone power relays, I
can do it with a relay if I must. I've never tried switching AC with
a power MOSFET before (just DC), can it be done? What other options
are there? Thanks.
-Dave
Comments
and hazardous to the health of your Stamp if you make a bad connection,
we recommend opto-coupling. A company called Opto-22 makes high
quality, optically coupled SSRs (solid-state relays) that are easy to
connect to digital circuits. If you want to roll-your-own (not
recommended), you can find plenty of stock circuits on the Internet
using the MOC3010/MOC3012 (opto-triac) to switch a power triac.
We carry a small range of Opto-22 parts:
http://www.parallax.com/detail.asp?product_id=27322
-- Jon Williams
-- Applications Engineer, Parallax
-- Dallas Office
Original Message
From: nuclearspin2000 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=zevd6IuFs6_kIT41IqWQ6qqkW_2NAJfF_Wq9AkOegYT03ufjdYaPf8h1gSxyLybSkKQcMhDCM-pIx1UURYj6pbP4Zg]nuclearspin2000@y...[/url
Sent: Thursday, January 22, 2004 8:02 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Switching AC loads
Hi All,
I need to be able to switch an AC load on/off with my Stamp but am
looking for alternatives to expensive, failure prone power relays, I
can do it with a relay if I must. I've never tried switching AC with
a power MOSFET before (just DC), can it be done? What other options
are there? Thanks.
-Dave
120vac@10amp or D2410 for 240vac@10amps. These are well proven in some
nasty industrial environments and can be driven by the stamp. I would use a
transistor switch between the stamp and the relay just to make the circuit a
bit more robust but it is not absolutely necessary if only switching one or
two of these relays. check out this web site for info on interfacing the
stamp to various devices.
http://www.geocities.com/jimforkin2003/
jim
Original Message
From: nuclearspin2000 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=K3GNVm36fULITk19GqvIXTtCxB1UDlAcx0PlYMZF2gBJZj2Ey9LP_rZ4kg3GutFzXrG-Sdkgl6BCYRUMAVbniUQ]nuclearspin2000@y...[/url
Sent: Thursday, January 22, 2004 9:02 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Switching AC loads
Hi All,
I need to be able to switch an AC load on/off with my Stamp but am
looking for alternatives to expensive, failure prone power relays, I
can do it with a relay if I must. I've never tried switching AC with
a power MOSFET before (just DC), can it be done? What other options
are there? Thanks.
-Dave
To UNSUBSCRIBE, just send mail to:
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aimed towards larger loads but work fairly well (I'm not sure about
'failure prone')
On Thu, 22 Jan 2004, nuclearspin2000 wrote:
> Hi All,
>
> I need to be able to switch an AC load on/off with my Stamp but am
> looking for alternatives to expensive, failure prone power relays, I
> can do it with a relay if I must. I've never tried switching AC with
> a power MOSFET before (just DC), can it be done? What other options
> are there? Thanks.
>
> -Dave
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and Body
of the message will be ignored.
>
>
> Yahoo! Groups Links
>
> To visit your group on the web, go to:
> http://groups.yahoo.com/group/basicstamps/
>
> To unsubscribe from this group, send an email to:
> basicstamps-unsubscribe@yahoogroups.com
>
> Your use of Yahoo! Groups is subject to:
> http://docs.yahoo.com/info/terms/
>
>
>
Sean T. Lamont, CTO / Chief NetNerd, Abstract Software, Inc. (ServNet)
Seattle - Bellingham - Vancouver - Portland - Everett - Tacoma - Bremerton
email: lamont@a... WWW: http://www.serv.net
"Do not fear mistakes, There Are None" - Miles Davis
This keeps the grounds and neutrals isolated. It is possible to put the
solid state relays into a separate sub-box so that the control circuit may
be worked on by "any Mr. All-Thumbs and Elbows" safely<G>. The SSR is
essentially a triac with the opto-isolator built in, and in a nice package
to boot.
I haven't had problems with SSRs failing, and I have shorted loads (on
purpose) through 80 Amp ones arrayed into a 3-phase switch. Still, my
situation may not be typical<G>.
NOTE: Solid state relays do dissipate heat. Consider heat sink needs when
driving loads above an Amp or so. Same with Triacs.
Find a Hamfest somewhere near. They usually have vendors with new and used
equipment and parts at attractive prices<G>.
Original Message
From: Sean T. Lamont .lost. [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=DBMHjmCwCpAosaEKTjuPUVRSR-dOiMzwtVtsGi5pCzCP6lCxrUyKw-UB7pY0nvpc4fTKrCDu3J7rIhO5k6k]lamont@a...[/url
Sent: Thursday, January 22, 2004 2:22 PM
To: basicstamps@yahoogroups.com
Subject: Re: [noparse][[/noparse]basicstamps] Switching AC loads
Triacs are cheap if you're not doing too much load. SSR's usually are aimed
towards larger loads but work fairly well (I'm not sure about 'failure
prone')
On Thu, 22 Jan 2004, nuclearspin2000 wrote:
> Hi All,
>
> I need to be able to switch an AC load on/off with my Stamp but am
> looking for alternatives to expensive, failure prone power relays, I
> can do it with a relay if I must. I've never tried switching AC with a
> power MOSFET before (just DC), can it be done? What other options are
> there? Thanks.
>
> -Dave
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject
> and Body of the message will be ignored.
>
>
> Yahoo! Groups Links
>
> To visit your group on the web, go to:
> http://groups.yahoo.com/group/basicstamps/
>
> To unsubscribe from this group, send an email to:
> basicstamps-unsubscribe@yahoogroups.com
>
> Your use of Yahoo! Groups is subject to:
> http://docs.yahoo.com/info/terms/
>
>
>
Sean T. Lamont, CTO / Chief NetNerd, Abstract Software, Inc. (ServNet)
Seattle - Bellingham - Vancouver - Portland - Everett - Tacoma - Bremerton
email: lamont@a... WWW: http://www.serv.net
"Do not fear mistakes, There Are None" - Miles Davis
To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
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state relays are fairly complicated beasts, but they allow you to do
things that you couldn't do with a triac, like switch a 60 amp 220 load
with 10 ma of control current.
On Thu, 22 Jan 2004, Grover Richardson wrote:
> Opto isolated triacs, aka solid state relays, are safer for the mundane<G>.
> This keeps the grounds and neutrals isolated. It is possible to put the
> solid state relays into a separate sub-box so that the control circuit may
> be worked on by "any Mr. All-Thumbs and Elbows" safely<G>. The SSR is
> essentially a triac with the opto-isolator built in, and in a nice package
> to boot.
>
> I haven't had problems with SSRs failing, and I have shorted loads (on
> purpose) through 80 Amp ones arrayed into a 3-phase switch. Still, my
> situation may not be typical<G>.
>
> NOTE: Solid state relays do dissipate heat. Consider heat sink needs when
> driving loads above an Amp or so. Same with Triacs.
>
> Find a Hamfest somewhere near. They usually have vendors with new and used
> equipment and parts at attractive prices<G>.
>
>
Original Message
> From: Sean T. Lamont .lost. [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=Difkb6bMr1au8bWQPn78dl5_O3Lt1U6eChAKdmSMKoLyFBilv7l_sHtIOuWbRTpN7n3Q0bj8qcakB8_rWTUdwF0]lamont@a...[/url
> Sent: Thursday, January 22, 2004 2:22 PM
> To: basicstamps@yahoogroups.com
> Subject: Re: [noparse][[/noparse]basicstamps] Switching AC loads
>
>
>
> Triacs are cheap if you're not doing too much load. SSR's usually are aimed
> towards larger loads but work fairly well (I'm not sure about 'failure
> prone')
>
> On Thu, 22 Jan 2004, nuclearspin2000 wrote:
>
> > Hi All,
> >
> > I need to be able to switch an AC load on/off with my Stamp but am
> > looking for alternatives to expensive, failure prone power relays, I
> > can do it with a relay if I must. I've never tried switching AC with a
> > power MOSFET before (just DC), can it be done? What other options are
> > there? Thanks.
> >
> > -Dave
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed. Text in the Subject
> > and Body of the message will be ignored.
> >
> >
> > Yahoo! Groups Links
> >
> > To visit your group on the web, go to:
> > http://groups.yahoo.com/group/basicstamps/
> >
> > To unsubscribe from this group, send an email to:
> > basicstamps-unsubscribe@yahoogroups.com
> >
> > Your use of Yahoo! Groups is subject to:
> > http://docs.yahoo.com/info/terms/
> >
> >
> >
>
> Sean T. Lamont, CTO / Chief NetNerd, Abstract Software, Inc. (ServNet)
> Seattle - Bellingham - Vancouver - Portland - Everett - Tacoma - Bremerton
> email: lamont@a... WWW: http://www.serv.net
> "Do not fear mistakes, There Are None" - Miles Davis
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
> Body of the message will be ignored.
>
>
> Yahoo! Groups Links
>
> To visit your group on the web, go to:
> http://groups.yahoo.com/group/basicstamps/
>
> To unsubscribe from this group, send an email to:
> basicstamps-unsubscribe@yahoogroups.com
>
> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
>
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and Body
of the message will be ignored.
>
>
> Yahoo! Groups Links
>
> To visit your group on the web, go to:
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>
> To unsubscribe from this group, send an email to:
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>
>
>
Sean T. Lamont, CTO / Chief NetNerd, Abstract Software, Inc. (ServNet)
Seattle - Bellingham - Vancouver - Portland - Everett - Tacoma - Bremerton
email: lamont@a... WWW: http://www.serv.net
"Do not fear mistakes, There Are None" - Miles Davis
was my intention<G>. I was ignoring the finer points. But you are
absolutely correct.
Original Message
From: Sean T. Lamont .lost. [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=ybuP9EBAdl3AJ8ogsWP9oaUSGAFKStJypfJVRRIlGwjEU_GUUyEbUpVPvFKiVnj1dgRirrkEJijIpSb_iLM]lamont@a...[/url
Sent: Thursday, January 22, 2004 3:06 PM
To: basicstamps@yahoogroups.com
Subject: RE: [noparse][[/noparse]basicstamps] Switching AC loads
Solid state relays are not the same as opto isolated triacs. Many solid
state relays are fairly complicated beasts, but they allow you to do things
that you couldn't do with a triac, like switch a 60 amp 220 load with 10 ma
of control current.
On Thu, 22 Jan 2004, Grover Richardson wrote:
> Opto isolated triacs, aka solid state relays, are safer for the
> mundane<G>. This keeps the grounds and neutrals isolated. It is
> possible to put the solid state relays into a separate sub-box so that
> the control circuit may be worked on by "any Mr. All-Thumbs and
> Elbows" safely<G>. The SSR is essentially a triac with the
> opto-isolator built in, and in a nice package to boot.
>
> I haven't had problems with SSRs failing, and I have shorted loads (on
> purpose) through 80 Amp ones arrayed into a 3-phase switch. Still, my
> situation may not be typical<G>.
>
> NOTE: Solid state relays do dissipate heat. Consider heat sink needs
> when driving loads above an Amp or so. Same with Triacs.
>
> Find a Hamfest somewhere near. They usually have vendors with new and
> used equipment and parts at attractive prices<G>.
>
>
Original Message
> From: Sean T. Lamont .lost. [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=ybuP9EBAdl3AJ8ogsWP9oaUSGAFKStJypfJVRRIlGwjEU_GUUyEbUpVPvFKiVnj1dgRirrkEJijIpSb_iLM]lamont@a...[/url
> Sent: Thursday, January 22, 2004 2:22 PM
> To: basicstamps@yahoogroups.com
> Subject: Re: [noparse][[/noparse]basicstamps] Switching AC loads
>
>
>
> Triacs are cheap if you're not doing too much load. SSR's usually are
> aimed towards larger loads but work fairly well (I'm not sure about
> 'failure
> prone')
>
> On Thu, 22 Jan 2004, nuclearspin2000 wrote:
>
> > Hi All,
> >
> > I need to be able to switch an AC load on/off with my Stamp but am
> > looking for alternatives to expensive, failure prone power relays, I
> > can do it with a relay if I must. I've never tried switching AC with
> > a power MOSFET before (just DC), can it be done? What other options
> > are there? Thanks.
> >
> > -Dave
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed. Text in the
> > Subject and Body of the message will be ignored.
> >
> >
> > Yahoo! Groups Links
> >
> > To visit your group on the web, go to:
> > http://groups.yahoo.com/group/basicstamps/
> >
> > To unsubscribe from this group, send an email to:
> > basicstamps-unsubscribe@yahoogroups.com
> >
> > Your use of Yahoo! Groups is subject to:
> > http://docs.yahoo.com/info/terms/
> >
> >
> >
>
> Sean T. Lamont, CTO / Chief NetNerd, Abstract Software, Inc. (ServNet)
> Seattle - Bellingham - Vancouver - Portland - Everett - Tacoma - Bremerton
> email: lamont@a... WWW: http://www.serv.net
> "Do not fear mistakes, There Are None" - Miles Davis
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject
> and Body of the message will be ignored.
>
>
> Yahoo! Groups Links
>
> To visit your group on the web, go to:
> http://groups.yahoo.com/group/basicstamps/
>
> To unsubscribe from this group, send an email to:
> basicstamps-unsubscribe@yahoogroups.com
>
> Your use of Yahoo! Groups is subject to:
> http://docs.yahoo.com/info/terms/
>
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject
> and Body of the message will be ignored.
>
>
> Yahoo! Groups Links
>
> To visit your group on the web, go to:
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>
> To unsubscribe from this group, send an email to:
> basicstamps-unsubscribe@yahoogroups.com
>
> Your use of Yahoo! Groups is subject to:
> http://docs.yahoo.com/info/terms/
>
>
>
Sean T. Lamont, CTO / Chief NetNerd, Abstract Software, Inc. (ServNet)
Seattle - Bellingham - Vancouver - Portland - Everett - Tacoma - Bremerton
email: lamont@a... WWW: http://www.serv.net
"Do not fear mistakes, There Are None" - Miles Davis
To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
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To visit your group on the web, go to:
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window air conditioner (120VAC) on/off during the summer which
doesn't already have this capability. The nameplate specifies 5.5A,
although it also says to use a 15A time delay fuse or circuit breaker
but I'm assuming the 5.5A rating is the continuous steady state
current rating. I've already worked out the finer electronics points
to make it work, now I just have to switch the power safely and
reliably either using triacs or power relays/optos with switching
transistors for relay coils if used. The finished unit will be in its
own enclosure BTW for obvious safety reasons. I know relays can get
warm (dissipate pwr) but is a heatsink necessary as long as you don't
overload the relay beyond it's rated specs? Thanks.
-Dave
--- In basicstamps@yahoogroups.com, "Sean T. Lamont .lost."
<lamont@a...> wrote:
>
> Triacs are cheap if you're not doing too much load. SSR's usually
are
> aimed towards larger loads but work fairly well (I'm not sure about
> 'failure prone')
>
> On Thu, 22 Jan 2004, nuclearspin2000 wrote:
>
> > Hi All,
> >
> > I need to be able to switch an AC load on/off with my Stamp but am
> > looking for alternatives to expensive, failure prone power
relays, I
> > can do it with a relay if I must. I've never tried switching AC
with
> > a power MOSFET before (just DC), can it be done? What other
options
> > are there? Thanks.
> >
> > -Dave
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed. Text in the
Subject and Body of the message will be ignored.
> >
> >
> > Yahoo! Groups Links
> >
> > To visit your group on the web, go to:
> > http://groups.yahoo.com/group/basicstamps/
> >
> > To unsubscribe from this group, send an email to:
> > basicstamps-unsubscribe@yahoogroups.com
> >
> > Your use of Yahoo! Groups is subject to:
> > http://docs.yahoo.com/info/terms/
> >
> >
> >
>
> Sean T. Lamont, CTO / Chief NetNerd, Abstract Software, Inc.
(ServNet)
> Seattle - Bellingham - Vancouver - Portland - Everett - Tacoma -
Bremerton
> email: lamont@a... WWW: http://www.serv.net
> "Do not fear mistakes, There Are None" - Miles Davis
>Specifically, what I want to do is automatically switch a 5400 BTU
>window air conditioner (120VAC) on/off during the summer which
>doesn't already have this capability. The nameplate specifies 5.5A,
>although it also says to use a 15A time delay fuse or circuit breaker
>but I'm assuming the 5.5A rating is the continuous steady state
>current rating. I've already worked out the finer electronics points
>to make it work, now I just have to switch the power safely and
>reliably either using triacs or power relays/optos with switching
>transistors for relay coils if used. The finished unit will be in its
>own enclosure BTW for obvious safety reasons. I know relays can get
>warm (dissipate pwr) but is a heatsink necessary as long as you don't
>overload the relay beyond it's rated specs? Thanks.
>
>-Dave
Dave -
Here is the simplest, and least expensive solution to your switching needs. Use
this X-10 Appliance Module, rated at 15 amps:
http://www.x10.com/automation/x10_am466.htm
At $ 14.00 USD per unit, I really can't think of a less expensive solution which
provides the same degree of safety. If these happen to be 220 volt units, that
can be accommodated as well by use of this $ 30.00 USD Appliance Module:
http://www.x10.com/automation/x10_hd243.htm
On the programming side, all you need to do is use the XOUT command to control
the module from your Stamp. See the Basic Stamp Manual for details of that
command. If you choose to expand this system, that can be easily done, as well
as using manual control from an X-10 console, or even an X-10 Telephone
Interface.
Lastly, this solution permits individual control of multiple outlets, by use of
the house and unit codes on the modules.
Use of these modules provides appropriate grounding, and there are no heat
worries. Since there is no direct connection between the Appliance Module and
the Stamp, there are no interfacing or safety problems either.
Regards,
Bruce Bates
For X10, you need a 'slave' (the unit you
plug your Air Conditioner into) and a 'controller'
(a unit which you use to send on/off signals
to the 'slave').
I recommend the X10 'firecracker' module.
This is a small RF module you connect to your
BS2, which 'talks' to a 'controller' module
with an antenna you plug in to the wall.
Around $20.00 for the package. Also comes
with an RF remote so YOU can control the
'slave'.
Thus, for $20.00 for the 'controller', and
$20.00 or so for the 'slave', you have a
complete solution which keeps you away from
the AC power lines.
--- In basicstamps@yahoogroups.com, Bruce Bates <bvbates@u...> wrote:
> At 04:10 AM 1/23/04 +0000, nuclearspin2000 wrote:
> >Specifically, what I want to do is automatically switch a 5400 BTU
> >window air conditioner (120VAC) on/off during the summer which
> >doesn't already have this capability. The nameplate specifies
5.5A,
> >although it also says to use a 15A time delay fuse or circuit
breaker
> >but I'm assuming the 5.5A rating is the continuous steady state
> >current rating. I've already worked out the finer electronics
points
> >to make it work, now I just have to switch the power safely and
> >reliably either using triacs or power relays/optos with switching
> >transistors for relay coils if used. The finished unit will be in
its
> >own enclosure BTW for obvious safety reasons. I know relays can
get
> >warm (dissipate pwr) but is a heatsink necessary as long as you
don't
> >overload the relay beyond it's rated specs? Thanks.
> >
> >-Dave
>
> Dave -
>
> Here is the simplest, and least expensive solution to your
switching needs. Use this X-10 Appliance Module, rated at 15 amps:
http://www.x10.com/automation/x10_am466.htm
>
> At $ 14.00 USD per unit, I really can't think of a less expensive
solution which provides the same degree of safety. If these happen to
be 220 volt units, that
> can be accommodated as well by use of this $ 30.00 USD Appliance
Module:
> http://www.x10.com/automation/x10_hd243.htm
>
> On the programming side, all you need to do is use the XOUT command
to control
> the module from your Stamp. See the Basic Stamp Manual for details
of that command. If you choose to expand this system, that can be
easily done, as well
> as using manual control from an X-10 console, or even an X-10
Telephone Interface.
> Lastly, this solution permits individual control of multiple
outlets, by use of the house and unit codes on the modules.
>
> Use of these modules provides appropriate grounding, and there are
no heat worries. Since there is no direct connection between the
Appliance Module and the Stamp, there are no interfacing or safety
problems either.
>
> Regards,
>
> Bruce Bates
Stamp without the RF remote. I did a Stamp Project of the Month about it
awhile back (I don't recall the exact link but it is the last or 2nd to last
document at http://www.awce.com/doclib.htm.
Regards,
Al Williams
AWC
* New Universal PCB fits 28/40 pin Stamp, Ubicom, more...
http://www.awce.com/gpmpu40.htm
Original Message
From: Allan Lane [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=KcjvMhmZsYFboo7lBJVDnxPZ7i7cT8Ctm9XuBA-dUFrwN7FokL8pWvRs7sdhQ7ao47ey91Vn4Nne4HSO9l4MytYLkg]allan.lane@h...[/url
Sent: Friday, January 23, 2004 8:33 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: Switching AC loads
Using the X10 is a good idea.
For X10, you need a 'slave' (the unit you
plug your Air Conditioner into) and a 'controller'
(a unit which you use to send on/off signals
to the 'slave').
I recommend the X10 'firecracker' module.
This is a small RF module you connect to your
BS2, which 'talks' to a 'controller' module
with an antenna you plug in to the wall.
Around $20.00 for the package. Also comes
with an RF remote so YOU can control the
'slave'.
Thus, for $20.00 for the 'controller', and
$20.00 or so for the 'slave', you have a
complete solution which keeps you away from
the AC power lines.
--- In basicstamps@yahoogroups.com, Bruce Bates <bvbates@u...> wrote:
> At 04:10 AM 1/23/04 +0000, nuclearspin2000 wrote:
> >Specifically, what I want to do is automatically switch a 5400 BTU
> >window air conditioner (120VAC) on/off during the summer which
> >doesn't already have this capability. The nameplate specifies
5.5A,
> >although it also says to use a 15A time delay fuse or circuit
breaker
> >but I'm assuming the 5.5A rating is the continuous steady state
> >current rating. I've already worked out the finer electronics
points
> >to make it work, now I just have to switch the power safely and
> >reliably either using triacs or power relays/optos with switching
> >transistors for relay coils if used. The finished unit will be in
its
> >own enclosure BTW for obvious safety reasons. I know relays can
get
> >warm (dissipate pwr) but is a heatsink necessary as long as you
don't
> >overload the relay beyond it's rated specs? Thanks.
> >
> >-Dave
>
> Dave -
>
> Here is the simplest, and least expensive solution to your
switching needs. Use this X-10 Appliance Module, rated at 15 amps:
http://www.x10.com/automation/x10_am466.htm
>
> At $ 14.00 USD per unit, I really can't think of a less expensive
solution which provides the same degree of safety. If these happen to
be 220 volt units, that
> can be accommodated as well by use of this $ 30.00 USD Appliance
Module:
> http://www.x10.com/automation/x10_hd243.htm
>
> On the programming side, all you need to do is use the XOUT command
to control
> the module from your Stamp. See the Basic Stamp Manual for details
of that command. If you choose to expand this system, that can be
easily done, as well
> as using manual control from an X-10 console, or even an X-10
Telephone Interface.
> Lastly, this solution permits individual control of multiple
outlets, by use of the house and unit codes on the modules.
>
> Use of these modules provides appropriate grounding, and there are
no heat worries. Since there is no direct connection between the
Appliance Module and the Stamp, there are no interfacing or safety
problems either.
>
> Regards,
>
> Bruce Bates
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But continuing with the question. As far as heat sinks for solid
state relays, we use the number of a Volt drop across the relay as the first
line of defense. So, if it's drawing 5.5 Amps continuously, the SSR will
dissipate 5.5 Watts. In reality, they (so far we have found, gotta say this
here<G>) have less Voltage drop across them, so this is (so far) a safe
assumption. The enclosure itself may represent a sufficient heat sink. If
it was mine, I would mount it to the side of the enclosure, and run the
unit. Feel every 30 seconds or so the side of the enclosure to see if it
gets too hot.
Not, I use a special test for temperatures. I touch the side of a box. I
say the words, "this isn't very hot, I think that I will take my finger off
the side of the box now." If I can't say that all BEFORE removing my
fingers from the side of the box, then the box is too hot and needs heat
sinking. I actually did an experiment years ago, and verified that too hot
to touch (but not burning) is in the zone where electronics will certainly
work, but will have shortened life.
Certainly, it is a crude method, and the circuit will survive if
it's hotter than you can touch. But if it's hot enough you can't touch it,
then the life of the components goes down. So, I design everything possible
such that I can place my hand on the item/heat sink for as long as I
wish<G>.
Original Message
From: Bruce Bates [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=bsgpRqHNnuwy1t7BfBWbvEoi4dut4D92HDRJjkvKkDA9_EhkL2kiWCRNlaxz76CdEjWKU30YWL6vd20vO36s4g]bvbates@u...[/url
Sent: Friday, January 23, 2004 4:10 AM
To: basicstamps@yahoogroups.com
Subject: Re: [noparse][[/noparse]basicstamps] Re: Switching AC loads
At 04:10 AM 1/23/04 +0000, nuclearspin2000 wrote:
>Specifically, what I want to do is automatically switch a 5400 BTU
>window air conditioner (120VAC) on/off during the summer which
>doesn't already have this capability. The nameplate specifies 5.5A,
>although it also says to use a 15A time delay fuse or circuit breaker
>but I'm assuming the 5.5A rating is the continuous steady state
>current rating. I've already worked out the finer electronics points
>to make it work, now I just have to switch the power safely and
>reliably either using triacs or power relays/optos with switching
>transistors for relay coils if used. The finished unit will be in its
>own enclosure BTW for obvious safety reasons. I know relays can get
>warm (dissipate pwr) but is a heatsink necessary as long as you don't
>overload the relay beyond it's rated specs? Thanks.
>
>-Dave
Dave -
Here is the simplest, and least expensive solution to your switching needs.
Use this X-10 Appliance Module, rated at 15 amps:
http://www.x10.com/automation/x10_am466.htm
At $ 14.00 USD per unit, I really can't think of a less expensive solution
which provides the same degree of safety. If these happen to be 220 volt
units, that
can be accommodated as well by use of this $ 30.00 USD Appliance Module:
http://www.x10.com/automation/x10_hd243.htm
On the programming side, all you need to do is use the XOUT command to
control
the module from your Stamp. See the Basic Stamp Manual for details of that
command. If you choose to expand this system, that can be easily done, as
well
as using manual control from an X-10 console, or even an X-10 Telephone
Interface. Lastly, this solution permits individual control of multiple
outlets, by use of the house and unit codes on the modules.
Use of these modules provides appropriate grounding, and there are no heat
worries. Since there is no direct connection between the Appliance Module
and the Stamp, there are no interfacing or safety problems either.
Regards,
Bruce Bates
To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
Yahoo! Groups Links
To visit your group on the web, go to:
http://groups.yahoo.com/group/basicstamps/
To unsubscribe from this group, send an email to:
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Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
AC and are only looking for ON-OFF then you can use a servo and a switch.
You can use a normal AC light switch and a cheap servo. The servo arm is
attached to the light switch using any of a variety of attachments that you can
get
at an R/C airplane or car store.
[noparse][[/noparse]Non-text portions of this message have been removed]
I have used good old power relays in industrial applications with Stamps for
years. ( 5-6 anyway).
If I was going to control that Air Conditioner I would use a good old P&B
(Potter & Brumfield) PRD series power relay. It comes in 12-120 Volt AC and DC
coils, has 30 amp contacts and does not need to be heat sinked.
The 24 VDC model is PRD-11DY0-24 Digikey number PB499-ND
There are 2 sets of contacts and they are spaced further apart than regular
relays. The contacts are silver coated to resist arcing when switching
inductive loads.
I have used this relay with big power transformers, ac motors, and even small
welding machines. They are cheap ($25 or so), and last forever.
I always double the contact rating, so a 15 amp Max circuit gets a 30 amp
relay contact. Cutting it closer could result in contacts getting welded
together.
I do not use SSr's on high current inductive loads as the current spikes can
damage them unless you buy the real expensive ones and put extra RC Filtering
on them. A 15 Amp SSR would not last long with this type of load.
The motor looks like a dead short for the first half line cycle, until the
magnetic field builds up.
During this time (8 ms at 60hz) the current can jump 800%. The relay can
handle this easily, but the SSR may not be so forgiving.
I use a small SSR to drive a 120 VAC relay coil. This way I don't need a
second power source. I use Croydom D2W202F (Digikey CC1069-ND) to run the relay.
This gives excellent isolation to the stamp, and there is no worries about
heat at all.
Also one of the other replies mentioned a 5 minute minimum off time. This is
a very good rule, as some compressors will start right up, but it slowly
destroys the mechanics.
The head pressure needs to bleed off before the motor restarts. With no
pressure it will start right up, but when the pressure is high the motor may
stall,
or just abuse itself to overcome the built up pressure. The start up current
will also be much higher in this mode also.
Hope this helps.
Alan Bradford
Plasma Technologies
In a message dated 1/22/04 11:13:07 PM Eastern Standard Time,
nuclearspin2000@y... writes:
Specifically, what I want to do is automatically switch a 5400 BTU
window air conditioner (120VAC) on/off during the summer which
doesn't already have this capability. The nameplate specifies 5.5A,
although it also says to use a 15A time delay fuse or circuit breaker
but I'm assuming the 5.5A rating is the continuous steady state
current rating. I've already worked out the finer electronics points
to make it work, now I just have to switch the power safely and
reliably either using triacs or power relays/optos with switching
transistors for relay coils if used. The finished unit will be in its
own enclosure BTW for obvious safety reasons. I know relays can get
warm (dissipate pwr) but is a heatsink necessary as long as you don't
overload the relay beyond it's rated specs? Thanks.
-Dave
[noparse][[/noparse]Non-text portions of this message have been removed]
own" kind of guy but I appreciate the links to the X-10 stuff which
would admittedly be easier and perhaps cheaper too. I've pasted
everyone's comments into my notes for future reference. Thanks again.
-Dave
--- In basicstamps@yahoogroups.com, plasmastamp@a... wrote:
> Hi Dave,
> I have used good old power relays in industrial applications with
Stamps for
> years. ( 5-6 anyway).
>
> If I was going to control that Air Conditioner I would use a good
old P&B
> (Potter & Brumfield) PRD series power relay. It comes in 12-120
Volt AC and DC
> coils, has 30 amp contacts and does not need to be heat sinked.
> The 24 VDC model is PRD-11DY0-24 Digikey number PB499-ND
> There are 2 sets of contacts and they are spaced further apart than
regular
> relays. The contacts are silver coated to resist arcing when
switching
> inductive loads.
>
> I have used this relay with big power transformers, ac motors, and
even small
> welding machines. They are cheap ($25 or so), and last forever.
>
> I always double the contact rating, so a 15 amp Max circuit gets a
30 amp
> relay contact. Cutting it closer could result in contacts getting
welded together.
>
> I do not use SSr's on high current inductive loads as the current
spikes can
> damage them unless you buy the real expensive ones and put extra RC
Filtering
> on them. A 15 Amp SSR would not last long with this type of load.
> The motor looks like a dead short for the first half line cycle,
until the
> magnetic field builds up.
> During this time (8 ms at 60hz) the current can jump 800%. The
relay can
> handle this easily, but the SSR may not be so forgiving.
>
> I use a small SSR to drive a 120 VAC relay coil. This way I don't
need a
> second power source. I use Croydom D2W202F (Digikey CC1069-ND) to
run the relay.
> This gives excellent isolation to the stamp, and there is no
worries about
> heat at all.
>
> Also one of the other replies mentioned a 5 minute minimum off
time. This is
> a very good rule, as some compressors will start right up, but it
slowly
> destroys the mechanics.
> The head pressure needs to bleed off before the motor restarts.
With no
> pressure it will start right up, but when the pressure is high the
motor may stall,
> or just abuse itself to overcome the built up pressure. The start
up current
> will also be much higher in this mode also.
>
> Hope this helps.
>
> Alan Bradford
> Plasma Technologies
>
>
>
>
>
> In a message dated 1/22/04 11:13:07 PM Eastern Standard Time,
> nuclearspin2000@y... writes:
> Specifically, what I want to do is automatically switch a 5400 BTU
> window air conditioner (120VAC) on/off during the summer which
> doesn't already have this capability. The nameplate specifies 5.5A,
> although it also says to use a 15A time delay fuse or circuit
breaker
> but I'm assuming the 5.5A rating is the continuous steady state
> current rating. I've already worked out the finer electronics
points
> to make it work, now I just have to switch the power safely and
> reliably either using triacs or power relays/optos with switching
> transistors for relay coils if used. The finished unit will be in
its
> own enclosure BTW for obvious safety reasons. I know relays can get
> warm (dissipate pwr) but is a heatsink necessary as long as you
don't
> overload the relay beyond it's rated specs? Thanks.
>
> -Dave
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]