BCT15 vs 996P2 Audio Output

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Adavis4

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Hi all,
I have successfully completed a project to have a bell ring (via relay) when my 996p2 activated in fire tone-out mode via using the AC voltage that exists in a 3.5mm stereo wire coming out of the headphone jack.

Because I didn't want to dedicate my 996P2 to this, I picked up a BCT15. Somehow though, something is different. If I remove the 996P2 and replace with the BCT15, the system fails to work. I did a little reading and testing and below is what I've found:



BCD996P2: headphone jack is stereo, putting out 6mW at 32ohm
BCd996P2: no voltage in stereo wire unless radio is making sound, 4-5V AC when radio is active.
BCT15: headphone jack is stereo, putting out (?) mW at 32ohm
BCT15: meter reads about 8v AC at startup and then it slowly bleeds to zero. Once at zero, I get no voltage even when radio is active and sound signal is flowing through the cable (verified with a speaker).

The BCT15 manual is confusing because I read the following:

Page 32: "Use an optional mono earphone or mono headset with proper impedance(32 Ω) for private listening"

Page 141: "Phone jack: 3.5mm Stereo type"

I didn't my own test with a pair of stereo headphones and get audio on both sides. I'm assuming this means it is a stereo jack.

If that is the case, I can't figure out why I'd get a different result. Any thoughts/tips?

I have to use the headphone jack because for various reasons the REc and ext speaker will not work for this project.

Thanks folks!
 

jonwienke

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BCT15: meter reads about 8v AC at startup and then it slowly bleeds to zero. Once at zero, I get no voltage even when radio is active and sound signal is flowing through the cable (verified with a speaker).

Your meter isn't working, or else you have it set to DC instead of AC.
 

Adavis4

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That is definitely a possibility, but it's certainly set in AC and i make no changes to the meter when I swap one scanner for the other. Works great with 996P2 and not with BCt15.

Even though the specs in the manual say it's a stereo jack and I get audio out of both of my headphones, this appears on the second page of the manual:

"Be sure to use only a monaural earphone or 32 Ω stereo headset. Use of an incorrect earphone or stereo headset might be potentially hazardous to your hearing. The output of the phone jack is monaural, but you will hear it in both headphones of a stereo headset."

Does that change anyone's thinking?
 

jonwienke

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Always use stereo headphones on Uniden scanners. Using a mono plug shorts out one side of the audio amplifier.
 

Adavis4

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Understood- Thanks!

Next set of clues:

My under standing of a single ended amp is that it delivers signal on the (+) wire and that the (-) wire is grounded- thus allowing me to read AC voltage between the two.

I'm doing some reading that says a bridged amp would have signal on both wires... a signal on the (+) wire and an inverse signal on the (-) wire. i would assume in this case, that i cannot necessarily read anything on my meter between the +/- wires on an bridged amp system. Is this correct?
 
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