Scanner over car audio speakers

Archiver

I'm a volunteer fireman and I would like to have my pager(which is
basically a miniature scanner that is triggered by a specific rf
freq.) setup to go through the car's speakers. That's the easy
part. What I saw in my uncle's state trooper car is when he had the
radio on and someone talked on the police radio, it would cut out the
music playing on the radio for that call. I would guess it would be
a relay setup of some sort. I was wondering if anyone knows or has
heard of such a setup.

Thanks,

Chris

Archiver

The "easiest" approach would be if your existing car radio
had an external amp with line level inputs. With a relay
wired so that the "default" off position would allow the
car radio to pass through to the amp, simply use a VOX type
circuit from your pager to engage the relay and switch the
signal feeding the amp from the radio to the pager.


>I'm a volunteer fireman and I would like to have my pager(which is
>basically a miniature scanner that is triggered by a specific rf
>freq.) setup to go through the car's speakers. That's the easy
>part. What I saw in my uncle's state trooper car is when he had the
>radio on and someone talked on the police radio, it would cut out the
>music playing on the radio for that call. I would guess it would be
>a relay setup of some sort. I was wondering if anyone knows or has
>heard of such a setup.
>
>Thanks,
>
>Chris
>

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Beau Schwabe Mask Designer National Semiconductor Corporation
500 Pinnacle Court, Suite 525
Home: polygon_man@h... Mail Stop GA1
Work: bschwabe@a... Norcross, GA 30071

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Archiver

Chris,

I'm a volunteer firefighter too, with Albion-Little River VFD, which is
located near Mendocino in CA. We run about 250 calls a year. What department
are you with?

Anyway, we have the Motarola Minitor II and III, which have a headphone
jack. You could use a comparator circuit to decide which to input to the car
speakers. There was a thread here recently about doing a similar thing in an
airplane.This person wanted to listen to the stereo and have traffic control
and such interupt. I forget the title of thread, maybe someone else will
remember. I also wouldn't be surprised if there was a product out there to
do this already.

I don't know about you, but my pager doesn't receive as well inside my car.
I have a handheld that I use when in my POV, which is better but not great.
We have crappy radio coms in my area. You might want to consider a scanner
with an external antenna. Plus then you won't have to mess with plugging in
your pager and unplugging it when a "vehicle VS tree" or similar call pages
out ;-). And if you are a scan hound or if you may want to hear all your tac
channels and such, you could set a scanner to scan all of the channels you
want.

Jonathan

www.madlabs.info

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Original Message

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From: "Chris Drzewiecki" <crd75@a...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, May 17, 2004 11:10 AM
Subject: [noparse][[/noparse]basicstamps] Scanner over car audio speakers


> I'm a volunteer fireman and I would like to have my pager(which is
> basically a miniature scanner that is triggered by a specific rf
> freq.) setup to go through the car's speakers. That's the easy
> part. What I saw in my uncle's state trooper car is when he had the
> radio on and someone talked on the police radio, it would cut out the
> music playing on the radio for that call. I would guess it would be
> a relay setup of some sort. I was wondering if anyone knows or has
> heard of such a setup.
>
> Thanks,
>
> Chris
>
>
>
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