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AC Dropout switch?

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wait a minute... in that last diagram, will there be current to the impulse relay when the switch is open? as i see it, the current will be allowed to pass through the first relay when there is no current....but...there is no current then for the second one either, is there?

and the pull switch is a great idea, but i want to avoid any drilling or extras in the wall, or more correctly, facade. yes, wireless LAN, or WLAN as its called here. the power supply has its own smoothing capacitor it seems, at least for half a second. would it be expensive to add a little more protection?
 
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wait a minute... in that last diagram, will there be current to the impulse relay when the switch is open? as i see it, the current will be allowed to pass through the first relay when there is no current....but...there is no current then for the second one either, is there?

Yes, there is power to the impulse relay when the switch is open. That's because RLY1 is no longer powered and its center and NC contacts close. Follow the Hot line from the top of RLY1's coil, to its center contact, through its NO contact (the condition with no power on RLY1), to the top of RLY2's coil.

Ken
 
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Hi Ef.Berlin,

I'm glad you liked the pull-switch idea, i've used it before in awkward situations where electrical solutions became difficult.

Have you considered increasing the value of the smoothing capacitor in the wlan ?
Enough to ride out the brief absence of power.

When i wrote that, maybe i did not explain myself very well.
I will try to clarify what i had in mind.

Sometimes, when one turns OFF electronic equipment,
its little lights will stay on for a short while, and it continues to operate for a
short while.

This is because the working parts inside run on DC, yet the mains supply is AC, so there
will be a rectifier circuit involved, and a smoothing capacitor.

Sometimes the smoothing capacitor is a little bit more than needed, and the unit will
"run-on" briefly after being switched OFF.

That is the smoothing capacitor i meant.

the power supply has its own smoothing capacitor it seems, at least for half a second.
would it be expensive to add a little more protection?

I must say, i am not at all sure what you mean here.
But no, capacitors are not expensive.

Ive rewritten this many times, as i thought i may have the wrong end of the stick.
Making the wireless LAN linger a little longer should enable those relays to do
what you want, just as you originally intended.

Best of luck with it, John :)
 
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john, you had said increase the smoothing capacitor, i understood add one, my fault. so would i just solder in a larger capacitor without making other changes to allow it to run longer than it already does(longer protection)?

ken, sorry still don't understand. the diagram is clear and i'm sure i understand the switching, but how can current exist at all when the push switch is open? are we relying on a leftover ac wave? or a pulse of power as the first relay powers down?
what i mean is, during the time sw1 is open, relay1 lets go, closing the circuit to relay2, but if sw1 is open, then there is no current on that circuit, correct?
 
You are absolutely right. DOH!. :( I found a company that makes Bistable Impulse relays that operate on "current loss", but it looked like they were custom, so I was thinking I would make a current loose with a second relay, but had the relay power wire to the other side of switch. When I rearranged the schematic I lost the wire. Thinking it still worked, I posted it. :(

By the way here's the relay I was looking at: **broken link removed**

I guess I'm back to the easiest solution: X10...off the shelf, digital communication over two power wire connection, no loss of power to the bridge at all, and not too expensive.

Ken
 
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Hi,

I think that Ken's answer, of using a bistable-type-relay that runs on AC, is dead right.
And i think its so good i may use it myself.
A press button to break the supply would operate it, and could be used at either end.
But i don't see why you have a second relay to drive it.
I think a simple divide by two would do.

I have never used those types of relay myself, but i had a little read of that page,
and it looks like an excellent answer to this.
I might use that arrangement myself.

Cheers, John :)
 
Hi Ef Berlin,

Your diagram from earlier in this post, showing a latching relay, looks fine at first.
But as you point out, it seems the interruption is a little too short to be reliable.

I would suggest using a Normally-Closed press-button interrupt the feed, however this
might be a little unreliable if the feed is not resumed quickly enough.
To counter this, i suggest increasing the capacitance in the smoothing circuit of the Wlan.

Enough so that when switched OFF, the unit visibly lingers before dying.
This would mean that the press button could be pressed and released,
before the Wlan unit faded away.

A similar press button could be introduced outside too, just in case you wanted to switch
the lighting on or off from outside.

Best of luck with it, John :)
 

but does that involve only finding the capacitor and changing it out for a bigger one?


Well, not usually.

with capacitors, you can just slap another one straight across the existing one.
They add together in parallel. (has to be apropriate voltage, and plus to plus)

Its not always easy to see which side is plus.
And if its very tight on room in there, it doesn't have to be mounted alonside the existing,
it could be on short leads to fit nearby.

This might not be a job for someone new to this sort of thing,
maybe you should try just replacing the DPST wall switch for a N/C press button switch,
you may well find that it is easy to operate it quickly enough.

If so, then that would be a fairly easy option.

John :)
 
from what i gather, a bistable relay and a latching one are the same thing? would there be a problem using these relays with constant (sporadically broken) power? i´m sure they are built only for pulses, is it okay to leave em on all day?

i will need to take a look at the power supply and see about upgrading that capacitance, even if i don´t end up using it, that´s really good to know. thanks

a search for x10 brought up all kinds of stuff, got link? is there a regular type wall switch that can be used?
 
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