AC current relay

I want to switch on some receptacles when another one is drawing
current.

I want my remote controlled TV to turn on the equipment ancillary to
the television - converter box, antenna rotor, speaker amp. Ideally
something that can sense down to 1 amp or so then energize the other
outlets, and uses minimal current itself.

These things used to be fairly common to switch off the other
components when the record changer played the last record and shut
itself off.

 

[John Fields]

On Tue, 27 Dec 2011 13:04:13 -0500, default wrote:

I want to switch on some receptacles when another one is drawing
current.

I want my remote controlled TV to turn on the equipment ancillary to
the television - converter box, antenna rotor, speaker amp. Ideally
something that can sense down to 1 amp or so then energize the other
outlets, and uses minimal current itself.

---
http://www.crmagnetics.com/Products/Assets/ProductPDFs/CR9300%20Series.pdf

Use the -ACA to directly drive a relay coil and the relay to switch
the mains to a plug strip

--
JF

 

[JeffM]

default wrote:

I want to switch on some receptacles
when another one is drawing current.

Some threads I remember pointed to COTS stuff

e.g. Sears current-sensing boxes.
The posts by DaveM were the most useful, but I can't spot those now.
http://groups.google.com/group/sci.electronics.design/search?group=sci.electronics.design&q=%22table+saw%22+vacuum+OR+%22shop+vac%22+-fingers+-Engrave+-solar+-jackhammer&qt_g=Search+this+group

 

[Sjouke Burry]

default wrote in news:6o1kf7lpo9oi5i8kmsulohug1f3v2d65u4@4ax.com:

I want to switch on some receptacles when another one is drawing
current.

I want my remote controlled TV to turn on the equipment ancillary to
the television - converter box, antenna rotor, speaker amp. Ideally
something that can sense down to 1 amp or so then energize the other
outlets, and uses minimal current itself.

These things used to be fairly common to switch off the other
components when the record changer played the last record and shut
itself off.
Put a full rectifier bridge in series with the

mains power of the tv, short the dc side with
a wire, wind some of that wire around a reed relay,
let the reed relay switch a heavier relay, and you
are where you want to be.

 

[m II]

Sjouke Burry wrote:

Put a full rectifier bridge in series with the
mains power of the tv, short the dc side with
a wire, wind some of that wire around a reed relay,
let the reed relay switch a heavier relay, and you
are where you want to be.

......brilliant......really brilliant.....sincerely......



mike

 

On Dec 27, 10:04 am, default wrote:

I want to switch on some receptacles when another one is drawing
current.

I want my remote controlled TV to turn on the equipment ancillary to
the television - converter box, antenna rotor, speaker amp.  Ideally
something that can sense down to 1 amp or so then energize the other
outlets, and uses minimal current itself.

These things used to be fairly common to switch off the other
components when the record changer played the last record and shut
itself off.

Another possibility. Our new TV has USB inputs. I'm using one to get
the +5 and trigger a solid state relay to turn on the audio amp.

 

[Bill Gill]

On 12/27/2011 12:04 PM, default wrote:

I want to switch on some receptacles when another one is drawing
current.

I want my remote controlled TV to turn on the equipment ancillary to
the television - converter box, antenna rotor, speaker amp. Ideally
something that can sense down to 1 amp or so then energize the other
outlets, and uses minimal current itself.

These things used to be fairly common to switch off the other
components when the record changer played the last record and shut
itself off.
I was wondering if this will work. Most of my electronics devices

don't turn on just by having power applied. You have to turn
each item on separately, after the power is applied.

Bill

 

On 27 Dec 2011 21:13:59 GMT, Sjouke Burry <s@b> wrote:

default wrote in news:6o1kf7lpo9oi5i8kmsulohug1f3v2d65u4@4ax.com:

I want to switch on some receptacles when another one is drawing
current.

I want my remote controlled TV to turn on the equipment ancillary to
the television - converter box, antenna rotor, speaker amp. Ideally
something that can sense down to 1 amp or so then energize the other
outlets, and uses minimal current itself.

These things used to be fairly common to switch off the other
components when the record changer played the last record and shut
itself off.
Put a full rectifier bridge in series with the
mains power of the tv, short the dc side with
a wire, wind some of that wire around a reed relay,
let the reed relay switch a heavier relay, and you
are where you want to be.

 

On 27 Dec 2011 21:13:59 GMT, Sjouke Burry <s@b> wrote:

default wrote in news:6o1kf7lpo9oi5i8kmsulohug1f3v2d65u4@4ax.com:

I want to switch on some receptacles when another one is drawing
current.

I want my remote controlled TV to turn on the equipment ancillary to
the television - converter box, antenna rotor, speaker amp. Ideally
something that can sense down to 1 amp or so then energize the other
outlets, and uses minimal current itself.

These things used to be fairly common to switch off the other
components when the record changer played the last record and shut
itself off.
Put a full rectifier bridge in series with the
mains power of the tv, short the dc side with
a wire, wind some of that wire around a reed relay,
let the reed relay switch a heavier relay, and you
are where you want to be.

I like the concept. Have you tried it? Seems to me a reed would buzz
at 60 hertz, and filtering a high current low voltage (what you'd
expect on the added coil to the reed relay) would take a very large
capacity cap.

Then something would have to protect the cap from an overvoltage with
a transient like turn on or degauss (this is a CRT TV)

Worth playing with though.

 

[Jasen Betts]

On 2011-12-28, default <default> wrote:

On 27 Dec 2011 21:13:59 GMT, Sjouke Burry <s@b> wrote:

default wrote in news:6o1kf7lpo9oi5i8kmsulohug1f3v2d65u4@4ax.com:

I want to switch on some receptacles when another one is drawing
current.

I want my remote controlled TV to turn on the equipment ancillary to
the television - converter box, antenna rotor, speaker amp. Ideally
something that can sense down to 1 amp or so then energize the other
outlets, and uses minimal current itself.

These things used to be fairly common to switch off the other
components when the record changer played the last record and shut
itself off.
Put a full rectifier bridge in series with the
mains power of the tv, short the dc side with
a wire, wind some of that wire around a reed relay,
let the reed relay switch a heavier relay, and you
are where you want to be.

I like the concept. Have you tried it? Seems to me a reed would buzz
at 60 hertz, and filtering a high current low voltage (what you'd
expect on the added coil to the reed relay) would take a very large
capacity cap.

It's rectified, so it would be 120Hz

you can use a hefty shorted turn around the coil (eg: a length of copper or aluminium tube)
instead of the cap.


--
⚂⚃ 100% natural

--- Posted via news://freenews.netfront.net/ - Complaints to news@netfront.net ---

 

On 29 Dec 2011 12:00:19 GMT, Jasen Betts <jasen@xnet.co.nz> wrote:

On 2011-12-28, default <default> wrote:
On 27 Dec 2011 21:13:59 GMT, Sjouke Burry <s@b> wrote:

default wrote in news:6o1kf7lpo9oi5i8kmsulohug1f3v2d65u4@4ax.com:

I want to switch on some receptacles when another one is drawing
current.

I want my remote controlled TV to turn on the equipment ancillary to
the television - converter box, antenna rotor, speaker amp. Ideally
something that can sense down to 1 amp or so then energize the other
outlets, and uses minimal current itself.

These things used to be fairly common to switch off the other
components when the record changer played the last record and shut
itself off.
Put a full rectifier bridge in series with the
mains power of the tv, short the dc side with
a wire, wind some of that wire around a reed relay,
let the reed relay switch a heavier relay, and you
are where you want to be.

I like the concept. Have you tried it? Seems to me a reed would buzz
at 60 hertz, and filtering a high current low voltage (what you'd
expect on the added coil to the reed relay) would take a very large
capacity cap.

It's rectified, so it would be 120Hz

you can use a hefty shorted turn around the coil (eg: a length of copper or aluminium tube)
instead of the cap.

Well my preliminary study indicates that it takes a fair number of
turns to energize a reed even with the original coil removed and it
does buzz.

The killer is the small wire size it takes to get the turns in there.
That would have to be fused separately.

I do have a solution that does work. But was looking for something
easy and cheap. I take split bobbin power transformers cut out the
secondary and rewind a couple of turns of heavy wire, use the primary
as a secondary and power a FWB to energize a solid state relay, or
optical coupler. On my water heater and AC compressor - but it can
work down to 40 watts with 5 turns of wire and a 240 volt primary.

Low and behold:
http://www.amazon.com/Smart-Strip-Protector-Autoswitching-Technology/dp/B0006PUDQK/ref=pd_cp_e_1

There's already 3 different brands of this sort of thing - had I known
what to search for.

 

[Jasen Betts]

On 2011-12-29, default <default> wrote:

Well my preliminary study indicates that it takes a fair number of
turns to energize a reed even with the original coil removed and it
does buzz.

The killer is the small wire size it takes to get the turns in there.
That would have to be fused separately.

yeah, the original reed relay coil is sized to a certain number of
ampere-turns, if you're running full appliance power through a
modified coil and want it to energise with 1A but survive 15A
it's going to need a much larger coil.


this may explain why the first electronic load detector circuit I
encountered used a triac instead of a relay as the detector,


L ------+-->|-->|--+-----> appliance
| |
+--|<--|<--+-[10]-+
| \
|___________________|>|__\ to relay and snubber
|<| /



OTOH if you parallel the modified relay coil with a diode and run it
from DC you just re-wind the coil to operate from 600mv instead of 6V
and let the diode handle the excess, you'd still need to replace the plastic
bobbin with a copper tube to stop buzzing though.


Your home built current transformers are probably much more
efficient than these designs that impose several diode drops in the
load path. I'm assuming you have a zener (or similar) limiting the
output voltage from the transformer.


--
⚂⚃ 100% natural

--- Posted via news://freenews.netfront.net/ - Complaints to news@netfront.net ---

 

On 29 Dec 2011 20:30:32 GMT, Jasen Betts <jasen@xnet.co.nz> wrote:

On 2011-12-29, default <default> wrote:

Well my preliminary study indicates that it takes a fair number of
turns to energize a reed even with the original coil removed and it
does buzz.

The killer is the small wire size it takes to get the turns in there.
That would have to be fused separately.

yeah, the original reed relay coil is sized to a certain number of
ampere-turns, if you're running full appliance power through a
modified coil and want it to energise with 1A but survive 15A
it's going to need a much larger coil.


this may explain why the first electronic load detector circuit I
encountered used a triac instead of a relay as the detector,


L ------+-->|-->|--+-----> appliance
| |
+--|<--|<--+-[10]-+
| \
|___________________|>|__\ to relay and snubber
|<| /



OTOH if you parallel the modified relay coil with a diode and run it
from DC you just re-wind the coil to operate from 600mv instead of 6V
and let the diode handle the excess, you'd still need to replace the plastic
bobbin with a copper tube to stop buzzing though.


Your home built current transformers are probably much more
efficient than these designs that impose several diode drops in the
load path. I'm assuming you have a zener (or similar) limiting the
output voltage from the transformer.

I didn't try the shading coil/tube to stop the relay from buzzing.
Now I'm curious to know how that would affect the turns of wire it
takes to energize.

I developed transformer the idea years ago using a pair of 12 position
rotary switches with 47 ohm resistors to put a load across the
secondary then calculated the output, voltage and current, with
various resistance's from 47 ohms to 4700. Peak power is close to the
DCR of the secondary (as expected) but resistance equal to or higher
still transfers a "lot" of power (in the milliwatt range).

For safety I've used diacs to crowbar any spikes on the high turns
ratio windings - seems to be working... water heater >10 years, AC >9
months.

The water heater sounds a piezo buzzer when it comes on and flashes a
light while on and sounds the buzzer again when the thermostat turns
it off.

The AC just flashes a light in proportion to the current it pulls and
tells me the compressor is running - it is a variable speed rotary
compressor, and works over close to a ten to one range.

I was secretly hoping that someone had found a way to modify a GFI
circuit to do what I want, and maybe do away with the effort (and cost
and size) in cutting up transformers.

 

[ehsjr]

default wrote:

<snip>

I was secretly hoping that someone had found a way to modify a GFI
circuit to do what I want, and maybe do away with the effort (and cost
and size) in cutting up transformers.

I posted a modified GFCI circuit that does what you want in 2005.
If you want, I'll email the schematic to you, or re-post on ABSE.
However, I did not use the current transformer that was part of
the GFCI, and I don't recall why I used a different one. I was
squeezing the whole thing inside a Belkin power strip, and it
might be that the CT that was originally part of the GFCI was
too big to fit.

Ed

 

On Sat, 31 Dec 2011 02:17:13 -0500, ehsjr <ehsjr@nospamverizon.net>
wrote:

default wrote:

snip


I was secretly hoping that someone had found a way to modify a GFI
circuit to do what I want, and maybe do away with the effort (and cost
and size) in cutting up transformers.

I posted a modified GFCI circuit that does what you want in 2005.
If you want, I'll email the schematic to you, or re-post on ABSE.
However, I did not use the current transformer that was part of
the GFCI, and I don't recall why I used a different one. I was
squeezing the whole thing inside a Belkin power strip, and it
might be that the CT that was originally part of the GFCI was
too big to fit.

Ed
Great. I sent an email removing nospam. I do have ABSE on the

server...

 

[ehsjr]

default wrote:

On Sat, 31 Dec 2011 02:17:13 -0500, ehsjr <ehsjr@nospamverizon.net
wrote:


default wrote:

snip

I was secretly hoping that someone had found a way to modify a GFI
circuit to do what I want, and maybe do away with the effort (and cost
and size) in cutting up transformers.

I posted a modified GFCI circuit that does what you want in 2005.
If you want, I'll email the schematic to you, or re-post on ABSE.
However, I did not use the current transformer that was part of
the GFCI, and I don't recall why I used a different one. I was
squeezing the whole thing inside a Belkin power strip, and it
might be that the CT that was originally part of the GFCI was
too big to fit.

Ed

Great. I sent an email removing nospam. I do have ABSE on the
server...

Got your e and sent the schematic.

Ed