Hello,

I have four radios in my vehicle, all with remote speakers (unpowered)
that are fairly close to each other. It's confusing sometimes when
squelch breaks, to identify which radio is active.

I'm wondering if there is a way to rig a circuit, so that a small LED
light can be inserted into the speaker wires somehow, so that the
light illuminates when the speaker is active.

Thanks for any help,

Mike
Tucson, AZ

"Mike McAuley" wrote in message
ink.net...
Hello,

I have four radios in my vehicle, all with remote speakers (unpowered)
that are fairly close to each other. It's confusing sometimes when
squelch breaks, to identify which radio is active.

I'm wondering if there is a way to rig a circuit, so that a small LED
light can be inserted into the speaker wires somehow, so that the
light illuminates when the speaker is active.

Thanks for any help,

Mike
Tucson, AZ

Mike,

I do not know what radio mfg. or models you are using, but I believe that
one of the GE MASTR heads had an option for an LED (or bulb) to perform such
a function.

Greg

Thanks Greg, I'm using Radio Shack remote speakers. They're very
small cube shaped speakers with mono mini-plugs on the end of
about a 10' wire. As I said, they're unpowered. I just have them
plugged into the aux speaker out connection on the radios.
Can you tell me more about the GE MASTR units?

Thanks


Mike,

I do not know what radio mfg. or models you are using, but I believe that
one of the GE MASTR heads had an option for an LED (or bulb) to perform
such
a function.

Greg

"Mike McAuley" wrote in message
ink.net...
Thanks Greg, I'm using Radio Shack remote speakers. They're very
small cube shaped speakers with mono mini-plugs on the end of
about a 10' wire. As I said, they're unpowered. I just have them
plugged into the aux speaker out connection on the radios.
Can you tell me more about the GE MASTR units?

Thanks

Mike

I use to operate a GE MASTR II VHF (110 watt model) mobile for 2 meters in
1980s and early 1990s. When I traded cars, I took out that big trunk unit,
but never installed it in my new car.

Kevin Custer, K3KKC has a very good web site on the MASTR II units (many
have been converted for repeater usage) as well as other GE models. In
fact, my old repeater club installed an old retired GE MASTR PRO (had a tube
final section) thirty years ago .. that worked quite well .. once WB9GGO
(sk) fixed many of its little problems (like cracking the tubes every ten
minutes) !

The MASTR II has a RX squelch logic signal (RUS) that is normally present at
the remote head. With that logic you can turn on a small LED or 12 volt
bulb when the receiver is unsquelched (useful if you have the speaker volume
turned down). GE had an option which was a resistor, bulb and bracket for
mounting in a spare "window" on the remote head and attaching to this logic
line.
RUS is the RX squelch logic signal for the MASTR II is available at J904-8
(RX Unsquelched Sensor). The MASTR II also has another signal called
"Carrier Activity Sensor" available at J901-16, but this signal usually not
used (results in increased chopping of weak signals).

You may have this logic present in your radio, but it will take a schematic
and/or service manual to trace it down and check how the logic is presented
for usage.

Greg

"Mike McAuley" wrote in message
ink.net...
Hello,

I have four radios in my vehicle, all with remote speakers (unpowered)
that are fairly close to each other. It's confusing sometimes when
squelch breaks, to identify which radio is active.

I'm wondering if there is a way to rig a circuit, so that a small LED
light can be inserted into the speaker wires somehow, so that the
light illuminates when the speaker is active.

Thanks for any help,

Mike

I forgot the link
http://www.repeater-builder.com/ge/mastrIIindex.html

gb

"Mike McAuley" wrote in message
nk.net...
Thanks again Greg for the info, but I guess what I'm looking for, is a way
to trigger the LED with just speaker level voltage. I don't really want to
run a separate wire to the speaker or tamper with any of the circuitry
inside the radio.

This doesn't sound much like rocket science, although it strikes me as more
hassle than it should be. First, you want to sample the audio with a high
impedance -- probably an op amp would do here. Then, you rectify the noise
and feed a comparator, or maybe just a transistor. Use that to drive a LED.

The actual mechanics of getting a wire to sample each speaker and then
placing an LED near each radio, or in some sort of arrangement that helps
you know what radio, seems to be as much of a hassle as the electronics.
Maybe you have a box that connects to each radio and then from there to the
speakers. If you make each LED a different color you would eventually
associate the color with the radio. Might work better than getting used to
the position if the LEDs are all close.

Interesting problem though. Practically all of my radios have either an LED
or an indication on the LCD that the squelch is open. Could be because I
tend to favor Icoms. But it doesn't seem to help remind me to engage brain
and think about what radio is talking before I pick up the mike!

--McD

"Mike McAuley" wrote in message
ink.net...
Hello,

I have four radios in my vehicle, all with remote speakers (unpowered)
that are fairly close to each other. It's confusing sometimes when
squelch breaks, to identify which radio is active.

I'm wondering if there is a way to rig a circuit, so that a small LED
light can be inserted into the speaker wires somehow, so that the
light illuminates when the speaker is active.

Thanks for any help,

Mike
Tucson, AZ


I'm just going to throw this out for thought....

Try using an audio transformer as a current transformer into a
high-efficiency LED. Break the wire to the speaker and insert the low
impedance winding of the transformer in series. Connect the LED to the high
impedance winding with an anti-parallel diode (1N4004, say). Use maybe a
10:1 turns ratio transformer (100:1 impedance ratio) from Mouser, Digikey,
or Radio Shack.

If one assumes 50 mW output power into 8 Ohms, that is about 80 mA of
current to the speaker. The transformer makes it about 4 mA into the LED
(the 1N4004 conducts in the opposite direction). I think 50 mW is a very low
estimate for the amount of audio you need in an auto. If the LED burns out,
use a higher turns ratio transformer.

The LED will flicker with the audio. The louder the audio, the less flicker
and the brighter the LED. Conversely, if the volume is low enough, the LED
will barely flicker and be mostly off.

Anyway, just an idea.

Good luck.

John
KD5YI