[geeks] Stupid Electronics Help...

[John Francini]

On Dec 31, 2012, at 12:41, Jonathan Katz <jon at jonworld.com> wrote:

> I found this which gives instructions on wiring directly into the factory amp,
> without having to use my relay and a second amp. I may go this route. Why do
> they use resistors and capacitors instead of a diode?
> 

Because audio signals aren't DC, but AC with frequencies between 20Hz and 20kHz.

John

> http://www.volvo-forums.com/index.php?showtopic=1497&st=0
> 
> 
> On Dec 31, 2012, at 1:52 AM, rjtoegel <rjtoegel at gmail.com> wrote:
> 
>> Also, you can drive five speakers from a stereo amp. The front and back can
> be
>> fed by each channel by using a fader control and the center front is just
>> between the hot leads from each channel.  That gives a difference between
> the
>> right and left channels.  Only problem is that in today's cars, the speaker
>> grounds may not be grounded.    Sometimes messing with the speaker wires
> will
>> make the car computer throw out weird errors since the audio may be tied in
>> with the computer.  If there are three wires from each speaker, don't mess
>> with it!  Trouble will ensue.
>> 
>> Bob
>> 
>> Sent from my iPod
>> 
>> On Dec 30, 2012, at 9:13 PM, Jonathan Katz <jon at jonworld.com> wrote:
>> 
>>> Thanks, everyone!
>>> 
>>> I found a DPDT at Radio Shack which seems to have solved my "crisis" 
>> other
>>> than the fact I mis-read the label and wired it up wrong. I gave up for
>>> tonight and will resume my shenanigans once it gets a tad warmer out.
>>> 
>>> The whole goal is to add an AUX in to my wife's Volvo. Her Volvo has a
>> fancy
>>> sound system that uses the MOST fiber-optic stuff, so you can't just patch
>>> something in like with typical systems. Using one of the radio/FM
>>> mini-broadcasters is a PITA and the quality is horrid since the car has an
>>> antenna that is integral with the tailgate(!)
>>> 
>>> Going through my pile of parts I had a spare car audio amplifier. I bought
>> it
>>> years ago at the firesale at Circuit City when they were going bankrupt.
>>> 
>>> I put together an aux-in 3.5mm port on the dash and ran wires to where the
>>> MOST amp is under the passenger seat. I also ran a 12V switch on the dash
>> and
>>> wired the hot 12V wire to under the seat.
>>> 
>>> The goal was to have the relay turn off the MOST amp (which is why when
> the
>>> relay is deactivated that pole should remain closed so operation is
> normal)
>>> and power on my amp. Then my amp would pump sound to the existing
> speakers,
>>> splicing into the existing wires to existing speakers. Because my spare
> amp
>> is
>>> only two channel and I'm powering five channels (LR, RR, LF, RF, and
> Center
>>> Front) I was planning on using diodes in-line on each channel so that with
>> the
>>> new amp hooked up I don't wind up bridging my entire set of speakers.
>>> 
>>> My diode idea should work, right?
>>> 
>>> On Dec 30, 2012, at 6:54 PM, rjtoegel <rjtoegel at gmail.com> wrote:
>>> 
>>>> That's what I said. It's probably easier to find a dual throw than just a
>>>> plain NC. Even Rat Shack carries them.
>>>> 
>>>> Bob
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