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Self Made Car Alarm - 555 Timer, Monostable Circuits, Astable --- Verification Needed

B

Ben Lessani

Jan 1, 1970
0
Hi all,

I've been hunting through car alarms for sale and I have realised they
are damned expensive for what they are. I started reading about 555
circuits and a variety of other topics that may be usefull in the
design of an alarm.

I have come up with this so far,

http://www.geocities.com/blessani/Final_Design.JPG (only 90K, dont
worry)
(You may need to open a new window and paste that address in,
geocities can be a touch irritating)

The whole alarm will be run off the 12V battery that is in the car, it
is very rudimentary and uses simple circuits to complete the final
project. After the 12V supply from the battery is a 9.6V battery - the
purpose of this is to provide a backup facility incase the main wire
is snipped.(I know it would make a lot more sense to buy an alarm -
but I dont want to, I want to attempt to make one for both the fun and
practical aspect).

The alarm will be (in theory) started by the short pulse of the
central locking pump. When I lock the doors (remote central locking),
a signal will be sent from the RF unit to the central locking vacuum -
but only a brief one.

The first use of the 555 is to de-bounce the signal sent, when the pin
3 is armed, it will, in turn arm a toggle switch (to keep the pulse
sent from the RF unit on until the second pulse to stop it) When this
switch is closed, it closes a relay which passes a current through the
monitoring section of the alarm. The blinking LED is to act as a
deterent to theives. The vibration switches will have to be armed 3 or
4 at a time (3 on the diagram), this is so rain or bumps to the car
won't trigger the alarm. They can be sat in various locations within
the vehicle. If any one of these switches closed, then the next part
of the circuit is armed, the timer. This is a 555 monostable timer set
to 33 seconds, it should (in theory) close the next part of the
circuit to let the siren go off for a fixed time period.

The relay arms the disruptive part of the alarm (sirens, indicator
flashes, headlight flashing - whatever springs to mind). The very last
astable circuit is to provide a pulse of 1s, this will continue to run
as long as the 33 seconds continue.

The alarm should all work in theory but I don't know about in
practice, it would be nice if one of you could review the design and
point out flaws etc, before I go and buy the components.

Sorry for the huge post, only way I could explain my first ever
circuit diagram - I don't know if its correct or not.



Ben Lessani

Please gimme a bell by email if you leave a post
([email protected])
 
K

Ken Taylor

Jan 1, 1970
0
Ben Lessani said:
Hi all,

I've been hunting through car alarms for sale and I have realised they
are damned expensive for what they are. I started reading about 555
circuits and a variety of other topics that may be usefull in the
design of an alarm.

I have come up with this so far,

http://www.geocities.com/blessani/Final_Design.JPG (only 90K, dont
worry)
(You may need to open a new window and paste that address in,
geocities can be a touch irritating)
More than a touch irritating - it clears the screen after redirecting to
localhost.

Ken
 
B

Ben Lessani

Jan 1, 1970
0
Yeah, you can't click the link, you have to copy and paste it into a
new window. Its to protect Geocities from people hosting information
on their servers for free.

<a target="_blank" href="http://www.geocities.com/blessani/Final_Design.JPG">Image
of design here</a>


Try the link above, I'm not sure if it accepts HTML
 
R

Robert Baer

Jan 1, 1970
0
Ben said:
Yeah, you can't click the link, you have to copy and paste it into a
new window. Its to protect Geocities from people hosting information
on their servers for free.

<a target="_blank" href="http://www.geocities.com/blessani/Final_Design.JPG">Image
of design here</a>

Try the link above, I'm not sure if it accepts HTML

One gets:
We're sorry, but this page is currently unavailable for viewing.
If this site belongs to you, please read this help page for more
information and assistance.


***
BTW, *HOW* does a car alarm get enough intelligence to make itself,
especially before it exists to (presumably) be intelligent?
 
W

Winfield Hill

Jan 1, 1970
0
Robert Baer wrote...
It doesn't matter, the design is defective on so many fronts that it
should be set aside and a new start made with a clean sheet of paper.

Thanks,
- Win

whill_at_picovolt-dot-com
 
S

Spehro Pefhany

Jan 1, 1970
0
Robert Baer wrote...

It doesn't matter, the design is defective on so many fronts that it
should be set aside and a new start made with a clean sheet of paper.

Thanks,
- Win


This is not a novel to be tossed aside lightly. It should be thrown
with great force.
-- Dorothy Parker


Best regards,
Spehro Pefhany
 
W

Winfield Hill

Jan 1, 1970
0
Spehro Pefhany wrote...
This is not a novel to be tossed aside lightly.
It should be thrown with great force.
-- Dorothy Parker

:>)

Thanks,
- Win

whill_at_picovolt-dot-com
 
F

Fred Bloggs

Jan 1, 1970
0
Winfield said:
Robert Baer wrote...


It doesn't matter, the design is defective on so many fronts that it
should be set aside and a new start made with a clean sheet of paper.

Thanks,
- Win

whill_at_picovolt-dot-com

Nonsense- aside from some minor details like relay contact/coil
installed backwards and exploding the NiCad, the logic is basically
there. The OP should not proceed with physical prototyping until he has
this worked out.
 
C

Chaos Master

Jan 1, 1970
0
Ben Lessani called The Usenet Police (tm) of sci.electronics.design and said to
the cops, at 12 Feb 2004 04:35:57 -0800:
Yeah, you can't click the link, you have to copy and paste it into a
new window. Its to protect Geocities from people hosting information
on their servers for free.

<a target="_blank" href="http://www.geocities.com/blessani/Final_Design.JPG">Image
of design here</a>

Place it in a .html page and use a image tag in HTML as in:

[HTML code follows. Not for newsreaders]

<html>
<head>
<title>My design</title>
</head>
<body>
<img src="http://www.geocities.com/blessani/Final_Design.JPG" alt="This is my
design">
</body>
</html>

[Ends here!]
 
W

Winfield Hill

Jan 1, 1970
0
Fred Bloggs wrote...
Nonsense- aside from some minor details like relay contact/coil
installed backwards and exploding the NiCad, the logic is basically
there. The OP should not proceed with physical prototyping until
he has this worked out.

ROFLOL. One of Fred's few truly humorous postings.

Thanks,
- Win

whill_at_picovolt-dot-com
 
B

Ben Lessani

Jan 1, 1970
0
Thanks for the criticisms/help. I realised the minor faults in it and
changed it. I built a prototype on a breadboard and it worked a treat,
my next stage is to move it onto a PCB.

What do the PCB boards come out like when you buy copper clad sheet,
draw on it with etch resistant pen, and wash off the excess copper
with a chemical. Are they reliable ?
 
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