Hi, my car was just broken into yesterday, so I decided it's time to
get a car alarm. It's an old car, so I bought a cheap (but good brand)
basic vibration sensing alarm. Being the tinkerer I am (and not wanting
to irritate my neighbors with false alarms), I want to install a timer
that will wait a little bit before sounding the siren.
I also bought another cheap alarm system ($20 on eBay) that instead of
a siren sends a message to a pager. Thus, assuming both alarms trigger,
the neighbor annoying siren won't go off immediately, but I will still
be informed. Ideally, these two systems should be combined, so that I'm
using the good brand vibration sensor to activate both the siren and
pager, but I'll leave that project for later. (Incidentally, I'm also
going to install a homemade fuel pump kill switch, but this won't be
connected to the alarm system.)
I'm thinking I'd need to put an initially open relay in series with the
siren and the timer in parallel. When the circuit closes (i.e. alarm
tries to go off) the timer gets activated and closes the relay after a
certain (hopefully adjustable) amount of time. When the alarm tries to
turn off the siren (i.e. I hit the stop button on the alarm's remote),
this will kill power to both the timer and siren. Doing so will reset
the timer so it's ready for next time. I suppose I could also live with
a timer that needs a manual reset using a button or whatever.
Anyone know where I can get such a timer? This timer needs to be
inexpensive, as I'm disabled and living off public assistance.
Before becoming disabled, I was a computer science major at UC
Berkeley, so I have basic electronics knowledge. My experience with
soldering, however, is limited to a single light sensing switch I made.
(That was a fun project, intended to operate a window shade that would
open with the morning sun.)
get a car alarm. It's an old car, so I bought a cheap (but good brand)
basic vibration sensing alarm. Being the tinkerer I am (and not wanting
to irritate my neighbors with false alarms), I want to install a timer
that will wait a little bit before sounding the siren.
I also bought another cheap alarm system ($20 on eBay) that instead of
a siren sends a message to a pager. Thus, assuming both alarms trigger,
the neighbor annoying siren won't go off immediately, but I will still
be informed. Ideally, these two systems should be combined, so that I'm
using the good brand vibration sensor to activate both the siren and
pager, but I'll leave that project for later. (Incidentally, I'm also
going to install a homemade fuel pump kill switch, but this won't be
connected to the alarm system.)
I'm thinking I'd need to put an initially open relay in series with the
siren and the timer in parallel. When the circuit closes (i.e. alarm
tries to go off) the timer gets activated and closes the relay after a
certain (hopefully adjustable) amount of time. When the alarm tries to
turn off the siren (i.e. I hit the stop button on the alarm's remote),
this will kill power to both the timer and siren. Doing so will reset
the timer so it's ready for next time. I suppose I could also live with
a timer that needs a manual reset using a button or whatever.
Anyone know where I can get such a timer? This timer needs to be
inexpensive, as I'm disabled and living off public assistance.
Before becoming disabled, I was a computer science major at UC
Berkeley, so I have basic electronics knowledge. My experience with
soldering, however, is limited to a single light sensing switch I made.
(That was a fun project, intended to operate a window shade that would
open with the morning sun.)