[Robotgroup] car audio stuff

[Andre Lamothe]

I bet someone on the list has an extra they would be willing to get rid of 
or a $50 one on eBay. But, doing electronics without a scope is like driving 
without a car :)

Andre'

----- Original Message ----- 
From: <mlists at resistive.net>
To: "The Robot Group Mailing List" <robotgroup at puremagic.com>
Sent: Wednesday, March 19, 2008 11:36 PM
Subject: Re: [Robotgroup] car audio stuff


> Lastly, do me a favor, get your oscope out there if you can, run a cable
> from the house power. And see if you can see the noise better and where
> its
> coming from, you can probe the power, ground, and differntial signals from
> ground, +12, and the audio right and left with no signal and get some
> better
> idea of where you major problem area is.

Yea, therein lies the problem - trying to work with this stuff without
owning a scope :)



>
> But, stick with the switch, its cool! Don't let noise beat you, you will
> learn alot once you kill it.
>
> Andre'
>
>
> ----- Original Message -----
> From: <mlists at resistive.net>
> To: "The Robot Group Mailing List" <robotgroup at puremagic.com>
> Sent: Wednesday, March 19, 2008 10:41 PM
> Subject: Re: [Robotgroup] car audio stuff
>
>
> Hey Andre' -
>
> Thanks, I'll give that a shot.  Oddly enough, the noise on the radio input
> seems to be minimized when the charge line is plugged in, but the noise on
> the ipod input seems to be minimized when the charge line is unplugged.  I
> had a 100uF cap across the chip power and the audio output sounded pretty
> muffled.  I'll have to play with it.
>
> -Nick
>
>
>> Nick,
>>
>> Sounds like you have a ground loop. But, tell me do you hear the noise
>> WITHOUT the power lines connected to the iPod? The first step is to
>> simplify
>> the circuit, so you can focus on each piece. If there is still noise
>> with
>> the power disconnected to the iPod, then the things to try are
>>
>> 1. Put a .1, 1uF, 10uF cap in parallel across your chip first off.
>> 2. Try putting an audio isolation 1:1 transformer in front of the signal
>> to
>> the iPod, really cheap, and will remove the ground from the iPod.
>>
>> Andre'
>>
>>
>> ----- Original Message -----
>> From: <mlists at resistive.net>
>> To: <robotgroup at puremagic.com>
>> Sent: Tuesday, March 18, 2008 11:06 PM
>> Subject: [Robotgroup] car audio stuff
>>
>>
>> Hey Robotgroup -
>>
>> Any audio or auto electronics folks out there?  I didn't have an aux
>> input
>> to my radio in my car, so I cut the leads where the tuner goes into the
>> circuit board on my radio and put in a switch for my ipod
>>
>> http://www.resistive.net/schematic.jpg
>>
>> I also added a power line so that I could charge it too (bought a cable
>> with an ipod interface) The only problem is that there's a faint noise
>> when the car's running (a whirring from the spark plugs and alternator
>> noise - automobiles are notoriously noisy to work in power-wise)  I get
>> a
>> little bit of a difference when the ipod charger is plugged in too, so
>> that bit of capacitance across the power and ground seems to affect it
>> as
>> well.  I tried to add a cap between the power and ground but it seemed
>> to
>> make the problem worse.  Anyone have any suggestions on how I can clean
>> up
>> my signal, I've done a lot of reading on ground loops but not quite sure
>> if I have some sort of loop or if the power to my audio switching chip
>> is
>> just not clean enough (or both)
>>
>> I'm pretty close to giving up on the chip and sticking a relay in there,
>> I
>> think I tried to get too fancy with the IC.
>>
>> Any suggestions would be much appreciated
>>
>> -Nick
>>
>> _______________________________________________
>> Robotgroup mailing list
>> Robotgroup at puremagic.com
>> http://lists.puremagic.com/cgi-bin/mailman/listinfo/robotgroup
>>
>> _______________________________________________
>> Robotgroup mailing list
>> Robotgroup at puremagic.com
>> http://lists.puremagic.com/cgi-bin/mailman/listinfo/robotgroup
>>
>
>
> _______________________________________________
> Robotgroup mailing list
> Robotgroup at puremagic.com
> http://lists.puremagic.com/cgi-bin/mailman/listinfo/robotgroup
>
> _______________________________________________
> Robotgroup mailing list
> Robotgroup at puremagic.com
> http://lists.puremagic.com/cgi-bin/mailman/listinfo/robotgroup
>


_______________________________________________
Robotgroup mailing list
Robotgroup at puremagic.com
http://lists.puremagic.com/cgi-bin/mailman/listinfo/robotgroup