simple alarm system ideas?

S

Spork

Guest
hello. I would like to install a very simple alarm system. I've been reading
a little about the professional models online and they have to many features
and most have very poor documentation for a beginner.

I was thinking of something simple like magnetic contacts on all exterior
doors wired to a piezo buzzer by my headboard.

I'm assuming I would use normally open contacts wired in parralell then
wired in series with a piezo buzzer? Do I need resistors or anything else?

I realise the alarm would cease if the wires were cut or the door was shut
but it would be enough to wake me up and hopefully startle the thief.

My other question is can those radio shack surface mount contacts be used on
a steel door with foam core without using some kind of stand off? I've heard
you can and cant so I dont know what I should do.

I appreciate any other ideas. im just learning about electronics so I want
to keep it simple.

thanks
 
"Spork" <sdfasdg@erw.com> wrote in message
news:m1jZc.7320$3l3.7160@attbi_s03...
hello. I would like to install a very simple alarm system. I've been
reading
a little about the professional models online and they have to many
features
and most have very poor documentation for a beginner.

I was thinking of something simple like magnetic contacts on all exterior
doors wired to a piezo buzzer by my headboard.

I'm assuming I would use normally open contacts wired in parralell then
wired in series with a piezo buzzer? Do I need resistors or anything else?

I realise the alarm would cease if the wires were cut or the door was shut
but it would be enough to wake me up and hopefully startle the thief.

My other question is can those radio shack surface mount contacts be used
on
a steel door with foam core without using some kind of stand off? I've
heard
you can and cant so I dont know what I should do.

I appreciate any other ideas. im just learning about electronics so I want
to keep it simple.

thanks
Click to expand...
I also would be interested on how to link this system up to a computer for
logging etc of movement.

thanks
JJ
 
Use normally closed contacts, and invert the signal using a relay or
transistor for controlling the buzzer.
That way, cutting the wires sounds the alarm.

If using a relay, connect all switches in series, and one end to +line and
the other to the relay coil.
Connect the other end of the relay coil to -line.
Connect the buzzer to the +line, and the other end to the NCcontact of the
relay
Connect the common of the relay to the -line.

If using the transistor, use a series resistor of say 2k2 in the base
connection (6-24V circuit).
Transistor can be something like a BC558 or BC337, a simple NPN-type of
minimum say 100-200mA.
Connect the buzzer to the +line and collector.
Connect the emitter to the -line.
Connect all switches in series, and one end to +line and the other to the
base-resistor of the transistor.

For as well transistor as relay circuit, the buzzer voltage should be as the
power supply.

Linking the system to a PC is fairly easy, using a simple off-the-shelf
multi-IO board.
That way, using a little programming, all circuits can be controlled
individually.
Most of these boards have a simple program delivered, so it's as easy as
connecting and running the program.

greetz


"Tamar Solutions" <James@REMOVEMEtamarsolutions.co.uk> wrote in message
news:ch51j5$6jn$1@news6.svr.pol.co.uk...

"Spork" <sdfasdg@erw.com> wrote in message
news:m1jZc.7320$3l3.7160@attbi_s03...
hello. I would like to install a very simple alarm system. I've been
reading
a little about the professional models online and they have to many
features
and most have very poor documentation for a beginner.

I was thinking of something simple like magnetic contacts on all exterior
doors wired to a piezo buzzer by my headboard.

I'm assuming I would use normally open contacts wired in parralell then
wired in series with a piezo buzzer? Do I need resistors or anything else?

I realise the alarm would cease if the wires were cut or the door was shut
but it would be enough to wake me up and hopefully startle the thief.

My other question is can those radio shack surface mount contacts be used
on
a steel door with foam core without using some kind of stand off? I've
heard
you can and cant so I dont know what I should do.

I appreciate any other ideas. im just learning about electronics so I want
to keep it simple.

thanks
Click to expand...
I also would be interested on how to link this system up to a computer for
logging etc of movement.

thanks
JJ
 
"peterken" <peter273@hotmail.com> wrote in message
news:ddqZc.233508$js1.12227650@phobos.telenet-ops.be...
Use normally closed contacts, and invert the signal using a relay or
transistor for controlling the buzzer.
That way, cutting the wires sounds the alarm.

If using a relay, connect all switches in series, and one end to +line and
the other to the relay coil.
Connect the other end of the relay coil to -line.
Connect the buzzer to the +line, and the other end to the NCcontact of the
relay
Connect the common of the relay to the -line.

If using the transistor, use a series resistor of say 2k2 in the base
connection (6-24V circuit).
Transistor can be something like a BC558 or BC337, a simple NPN-type of
minimum say 100-200mA.
Connect the buzzer to the +line and collector.
Connect the emitter to the -line.
Connect all switches in series, and one end to +line and the other to the
base-resistor of the transistor.

For as well transistor as relay circuit, the buzzer voltage should be as
the
power supply.

Linking the system to a PC is fairly easy, using a simple off-the-shelf
multi-IO board.
That way, using a little programming, all circuits can be controlled
individually.
Most of these boards have a simple program delivered, so it's as easy as
connecting and running the program.

greetz


"Tamar Solutions" <James@REMOVEMEtamarsolutions.co.uk> wrote in message
news:ch51j5$6jn$1@news6.svr.pol.co.uk...

"Spork" <sdfasdg@erw.com> wrote in message
news:m1jZc.7320$3l3.7160@attbi_s03...
hello. I would like to install a very simple alarm system. I've been
reading
a little about the professional models online and they have to many
features
and most have very poor documentation for a beginner.

I was thinking of something simple like magnetic contacts on all exterior
doors wired to a piezo buzzer by my headboard.

I'm assuming I would use normally open contacts wired in parralell then
wired in series with a piezo buzzer? Do I need resistors or anything
else?

I realise the alarm would cease if the wires were cut or the door was
shut
but it would be enough to wake me up and hopefully startle the thief.

My other question is can those radio shack surface mount contacts be used
on
a steel door with foam core without using some kind of stand off? I've
heard
you can and cant so I dont know what I should do.

I appreciate any other ideas. im just learning about electronics so I
want
to keep it simple.

thanks




I also would be interested on how to link this system up to a computer for
logging etc of movement.

thanks
JJ
Click to expand...
Thanks - so would a PIC chip is what I would need?
 
"Spork" <sdfasdg@erw.com> wrote in message
news:m1jZc.7320$3l3.7160@attbi_s03...
hello. I would like to install a very simple alarm system. I've been
reading
a little about the professional models online and they have to many
features
and most have very poor documentation for a beginner.

I was thinking of something simple like magnetic contacts on all exterior
doors wired to a piezo buzzer by my headboard.

I'm assuming I would use normally open contacts wired in parralell then
wired in series with a piezo buzzer? Do I need resistors or anything else?

I realise the alarm would cease if the wires were cut or the door was shut
but it would be enough to wake me up and hopefully startle the thief.

My other question is can those radio shack surface mount contacts be used
on
a steel door with foam core without using some kind of stand off? I've
heard
you can and cant so I dont know what I should do.

I appreciate any other ideas. im just learning about electronics so I want
to keep it simple.

thanks
Click to expand...
Wire the contacts in series with a relay coil and the relay's own contacts
so that when the relay drops out it can not be reset until you reset it.
You would need a relay with two contacts. SPDT (single pole double throw)
The coil voltage should match your supply voltage. The supply should first
go to the relay's common. The N.O. (normally open, the one open when the
relay is not energized) goes to the relay coil. The N.C. contact goes to the
sounding device.
The trip contacts are in series with the relay coil. You have to manually
arm the alarm. Put a N.O. push button switch between the relay common and
N.O.

Regards,
Tom
 
would it be safe to use a 12 volt wall wart for this project? I was thinking
I could use a louder piezo and not worry about batteries. would that be
safe?

thanks

"Tom Biasi" <tombiasi@REMOVETHISoptonline.net> wrote in message
news:EnDZc.42137$Es2.18444221@news4.srv.hcvlny.cv.net...
"Spork" <sdfasdg@erw.com> wrote in message
news:m1jZc.7320$3l3.7160@attbi_s03...
hello. I would like to install a very simple alarm system. I've been
reading
a little about the professional models online and they have to many
features
and most have very poor documentation for a beginner.

I was thinking of something simple like magnetic contacts on all
exterior
doors wired to a piezo buzzer by my headboard.

I'm assuming I would use normally open contacts wired in parralell then
wired in series with a piezo buzzer? Do I need resistors or anything
else?

I realise the alarm would cease if the wires were cut or the door was
shut
but it would be enough to wake me up and hopefully startle the thief.

My other question is can those radio shack surface mount contacts be
used
on
a steel door with foam core without using some kind of stand off? I've
heard
you can and cant so I dont know what I should do.

I appreciate any other ideas. im just learning about electronics so I
want
to keep it simple.

thanks

Wire the contacts in series with a relay coil and the relay's own contacts
so that when the relay drops out it can not be reset until you reset it.
You would need a relay with two contacts. SPDT (single pole double throw)
The coil voltage should match your supply voltage. The supply should first
go to the relay's common. The N.O. (normally open, the one open when the
relay is not energized) goes to the relay coil. The N.C. contact goes to
the
sounding device.
The trip contacts are in series with the relay coil. You have to manually
arm the alarm. Put a N.O. push button switch between the relay common and
N.O.

Regards,
Tom
Click to expand...
 
Spork wrote:

would it be safe to use a 12 volt wall wart for this project? I was
thinking I could use a louder piezo and not worry about batteries. would
that be safe?
Click to expand...
Sure, as long as you don't stick your tongue between the contacts. ;-)

Cheers!
Rich
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top