Re: Unusual Challenge

[Jim Davis <alarminex@xxxxxxx>]

On Friday, October 22, 2021 at 8:52:59 AM UTC-4, ABLE1 wrote:
> Ok Guys!!! Here you go. After reading you should=20
> be ABLE to get a good nights sleep. :-)=20
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> And now for the rest of the story!!=20
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> I had installed this setup in 2013 and it worked great with=20
> some minor issues over the years. Batteries, switch, etc.=20
> There were some reports of missed signals but was never sure=20
> if it was the RF signal loss or the human ear missing the=20
> burp of the sounder. It has been just recently that they=20
> have know that it has been more of an issue and called me=20
> back to help work out a different plan to get the signals=20
> better so that they would not miss a customer in the showroom.=20
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> When I got there last week as I said I checked the batteries=20
> and they were a bit low so I replaced with new. Not that it=20
> made much difference but it did miss a signal and I thought is=20
> was due to the fact that I triggered the door to fast. Assuming=20
> that the receiver or transmitter had some delay built in for=20
> excessive trips.=20
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> I moved the transmitter to the shop and it worked every time while=20
> there. Placed the transmitter back in the attic above the showroom=20
> and I put the transmitter back in the attic above the showroom where
> it was but staff was in a meeting so I could not test.=20
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> Was told later that they tried it and it did not work a total of 3 times=
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> Now the receiver has a wire about 7" long as a antenna. I have=20
> it hanging over the edge of a window so that the walls would not block=20
> the RF signal. The Transmitter is in the attic space on a vertical=20
> 2x4. The only thing that might block the signal would be the plywood=20
> and asphalt shingles on the roof, 70' of distance, bug screen and glass=
=20
> window.=20
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> Needless to say this is a intermittent problem that is NOW not working!!
> Now for the revel!!!=20
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> It was mentioned the the bug screen was a metal mesh type.=20
> And I was asked if that could be causing the problem. I said=20
> that I did not think it would but, it certainly would not have any=20
> bad effects at this time of year to remove the screen. Well=20
> they did in the afternoon and did another test and the system=20
> burped the horn 13 out of 13 times. =F0=9F=98=AE WHAT!!!!=20
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> They did this with the window open as well. They are going to test=20
> with the window shut the next day to see what the results will be.=20
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> They tested with the window closed the and it worked just fine 5 times.=
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> I did some searching online and metal mesh screens as far as I can=20
> find are not an issue with RF. That is unless I am involved!!!=20
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> What I also found out was that this window is where they put a small=20
> A/C unit during the summer. Needless to say they have to remove the=20
> wire mesh screen to install the A/C and then they re-install the=20
> screen when they take the A/C out. If they remember to do so.=20
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> So this problem is sometimes there and sometimes not there!!!=20
> a.k.a. A intermittent problem!! Now SOLVED!!!=20
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> I strongly suggested that they get the screen frame re-screened with=20
> a NYLON MESH screen!!!=20
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> Hope you enjoyed the story!!=20
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> Les
Hmmm
So - - - maybe making the antenna a little longer so it could stick outside=
 the building would have helped (?)=20
.
Re: The resistor. As I understand it, the closed circuit contact is wired f=
rom ground to the trigger terminal. Without a resistor, when the switch ope=
ns, the trigger terminal just goes from negative to "float". When you add t=
he resistor, which is wired to the positive terminal when the switch opens,=
 it "pulls" the trigger terminal to Positive. Which is a definite swing fro=
m negative to positive rather than to just to a float level. Changing compo=
nent values on the relay PCB over the years could change the sensitivity le=
vel of he trigger input making the relay output of the board a "sometime" t=
hing.
.=20
With regard to the screen affecting the signal, I know microwave ovens util=
ize the fact that screens block microwaves so you can look inside the oven =
glass. I'm thinking of a situation that if you had a low frequency transmit=
ter and a receiver and you put one inside and one outside of the building w=
ith a metal window screen in between and then - - - still in the line of si=
ght but begin moving one device further and further to the side  - - - the =
increasing angle would, in effect, make the holes in the screen smaller and=
 smaller. Perhaps affecting the signal.
Is the window looking straight at the other building or is it off to the si=
de?
.
I'm also thinking that I'm putting wireless window transmitters behind case=
ment window metal frame, metal screens all the time with no problems.