Re: sensor choice for "gong detect"? & invisible light switches

["Jim" <alarminex@xxxxxxx>]

Tracker wrote:
> Hello, all.  Long time no read etc.
>
> Anybody ever *actually done* a sensor on a heavy bell?  (It's a
> large-size "Mission Bell" by Tom Torrens, if you care...  To be used as
> a doorbell, well, actually as a button replacement for a DSC door box.)
>  Specifically triggered by the resonating from the gong itself, no
> stuff like mallet switchhooks or motion sensor on the swinging mount...
>  I thought about an old-style glass break, but getting the frequency
> right would be a trick.
>
> Also does anybody know if commercially cheap density sensors can be
> used to determine if a finger is placed on the other side of sheetrock?
>  I'm gonna go do some experiments, so don't shoot me for asking first.
> But if someone has *already* done it, please let me know.  Why did this
> come up?  Well, I was looking at a Leviton "Acenti" ad the other day,
> and thought, "Why on earth does anybody want a larger, more prominent
> light switch?!"  Remember the Pass&Seymour/Legrand ones?  Ugly. as.
> sin.  Anyway, shouting "lights" at some comput er is silly, and motion
> sensors don't have the positive control (or on-location dimming)
> needed.  Again, don't flame me about greasy spots on the wall, or
> repairability of buried switches -- just, *if* you've done it, pretty
> please tell me what you learned.
>
> Thanks in advance!

For the "touch" switch, you'll usually find in some basic hobby
electronic books, Capacitive switches. These are the devices that
you'll find in table lamps that turn on and off by touching the metal
portion of the lamp. There are also some wall switches that will do the
same thing with the addition of dimming or brightning by holding your
finger to the metal surface of the switch. With the hobby switch
circuitry, if you experiment a little, you can change some component
values that will allow you to simply pass your hand near the sensor
rather than having to touch it. This way you could bury it in the wall
but not have to actually touch the wall to activate it. You'd have to
interface the output to a relay to operate the lights.

As far as the bell goes, a simple old fashioned vibration sensor should
do the trick. The Ademco # 11 vibration sensor is still avaiable or any
similar unit should do it. They're adjustable so you can set it to what
ever it takes to cause it to trip. Of course, you'd have to provide the
relay and power circuit to utilize the output.


But ..... in a pinch ........ don't forget about the Clapper :->