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Science Forum Index » Electronics - Basics Forum » alarm switch...
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| steve... |
 Posted: Sun May 11, 2008 3:42 am |
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I require alarm systems for both personal and house.
From seeing various alarm projects, there is no detail about how the
alarm is set off.
For example, a house alarm could be triggered by opening a door.
But the diy circuit notes merely say that power supply will trigger
the alarm on.
There should be a special kind of switch that will sense motion, or
breakage of a (window) latch, etc.
Could anyone please explain.
Yours sincerely
Steve |
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| JeffM... |
| Posted: Sun May 11, 2008 10:00 am |
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| Mike Wahler... |
| Posted: Sun May 11, 2008 10:38 am |
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"steve" <kvsteve at (no spam) gmail.com> wrote in message
news:a2c5fbe6-6beb-40f3-a0e1-3e1656e5e955 at (no spam) p25g2000pri.googlegroups.com...
Quote:
I require alarm systems for both personal and house.
From seeing various alarm projects, there is no detail about how the
alarm is set off.
For example, a house alarm could be triggered by opening a door.
But the diy circuit notes merely say that power supply will trigger
the alarm on.
There should be a special kind of switch that will sense motion, or
breakage of a (window) latch, etc.
Could anyone please explain.
See:
http://www.mkwahler.net/alarm.GIF
When switch is open, LED illuminates.
When switch is closed, LED turns off.
Be sure to choose resistor to match your
desired voltage (e.g. for red LED with 5
volts use 330 ohms).
LED indicator could be replaced or supplemented
with e.g. a buzzer.
-Mike |
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| David L. Jones... |
| Posted: Sun May 11, 2008 4:52 pm |
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"steve" <kvsteve at (no spam) gmail.com> wrote in message
news:a2c5fbe6-6beb-40f3-a0e1-3e1656e5e955 at (no spam) p25g2000pri.googlegroups.com...
Quote:
I require alarm systems for both personal and house.
From seeing various alarm projects, there is no detail about how the
alarm is set off.
For example, a house alarm could be triggered by opening a door.
But the diy circuit notes merely say that power supply will trigger
the alarm on.
There should be a special kind of switch that will sense motion, or
breakage of a (window) latch, etc.
Passive IR sensors are used to detect "movement"
http://en.wikipedia.org/wiki/Passive_infrared_sensor
Piezoelectric vibration sensors are used to detect window breakage:
http://en.wikipedia.org/wiki/Piezoelectric_sensor
Magnetic reed switches are used to detect door and window opening etc.
http://en.wikipedia.org/wiki/Reed_switch
A bit of advice - DON'T try and build your own alarm, it's waste of time,
but one that is properly designed to be reliable and bug free to prevent
false alarms.
Dave. |
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| Jamie... |
| Posted: Sun May 11, 2008 4:53 pm |
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steve wrote:
Quote:
I require alarm systems for both personal and house.
From seeing various alarm projects, there is no detail about how the
alarm is set off.
For example, a house alarm could be triggered by opening a door.
But the diy circuit notes merely say that power supply will trigger
the alarm on.
There should be a special kind of switch that will sense motion, or
breakage of a (window) latch, etc.
Could anyone please explain.
Yours sincerely
Steve
I assume you're talking about a car alarm ?
Most of those do power supply sensing among other things.
What this means is, if some one opens the door which would prompt
some electrical device in the car to activate like the doom light, the
alarm unit will detect a power flicker from the lights coming on.
That is just one example.
--
http://webpages.charter.net/jamie_5" |
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| steve... |
| Posted: Thu May 15, 2008 5:36 am |
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On May 12, 1:00 am, JeffM <jef... at (no spam) email.com> wrote:
Quote: steve wrote:
From seeing various alarm projects,
there is no detail about how the alarm is set off.
This is something that a search engine could easily find for you.
This link points to a site
that has all kinds of answers about this sort of thing.http://www.google.com/search?q=burglar-alarm+howstuffworks
That is a good term to add to such searches.
There should be a special kind of switch that will sense motion,
That is much more than a "switch".
or breakage of a (window) latch, etc.
That isn't a "switch" either.http://www.google.com/images?q=window-bug+alarm+OR+securityhttp://www.google.com/images?q=Traditional-lead-tape+alarm+OR+securit...
You will obviously have to buy these.
The old name in alarms is Alarm Device Manufacturing COmpanyhttp://www.google.com/search?q=ADEMCO
Go poke around their site and those of other such companies.
You could also easily have used a search enginehttp://groups.google.com/groups/search?q=burglar-alarms+-uk
to find out that this is the wrong group for burglar alarmshttp://groups.google.com/group/alt.security.alarms
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Thanks to everyone for their replies.
Please note that I had mentioned the requirement of a personal alarm
in my post.
My friend works as a social worker in a bad neighbourhood.
He is frail and therefore requires a personal protection device.
I was wondering if a stun device could be made, by collecting energy
in a single electronic part.
Then the energy could be released on the attacker. |
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| David L. Jones... |
| Posted: Thu May 15, 2008 3:58 pm |
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"steve" <kvsteve at (no spam) gmail.com> wrote in message
news:bef5b4d5-51d3-4d6d-9e5e-Thanks to everyone for their replies.
Quote: Please note that I had mentioned the requirement of a personal alarm
in my post.
My friend works as a social worker in a bad neighbourhood.
He is frail and therefore requires a personal protection device.
I was wondering if a stun device could be made, by collecting energy
in a single electronic part.
Then the energy could be released on the attacker.
They are called stun guns. May not be legal.
A cane is legal, learn how to use one of those:
http://www.gojushorei.com/canetechniques.htm
Also, try typing "personal alarm" into Google, plenty of help and/or panic
button devices available.
Dave. |
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