I tested the system in the car today on my hour long commute and really didint notice any noise... I heard some fuzz and stuff when i was booting but then it went away.
One of the big things that i noticed is the amp POP when turning it off... turning it on is fine since its delayed becuase i use the amp power turn on from the M1-ATX.
So i need to find a way to turn the amp off before the computer hibernates...
1990 Jeep Cherokee
2000 VW Golf TDI 4dr
2005 VW GTI MKIV - SOLD
Webdog, our experience is identical.
There is noise, it's scratching and such. It's really faint and I only notice it while booting or when I have the volume muted or set to 0 and the environment is quiet. If the car is moving at all or audio is playing the noise is drowned out. But, I know it's there....
Also, I get the same pop on standby/hibernate. You said you're using the m1-atx remote turn on, is that your 12V+ source for the regulator?
My worklog.
Status: VM GTI sold, got out of the CarPC tinkering hobby, but I still think about getting back in.
Yea that’s where I am getting the power for the regulator...Originally Posted by kbyrd
I’m going to try grounding the motherboard later when I get home maybe that will fix it, since I didn’t have any noise at all using a laptop or portable cd player.
Have we figured out a way to make the amp turn off instantly? Maybe we need a relay on the IGN line so when we turn the key off it cuts the amp instantly before the computer will be able to make it pop...
At least there is no alternator whine like my old car that was so much worse then a little fuzzy sound in the audio.
Another option is to modify the M1-ATX to wait like 15 seconds or however long it takes to boot the computer before turning the amp on so that way there is no sound until the computer is on, or use a relay controller so it will flip it on once the computer is online.
1990 Jeep Cherokee
2000 VW Golf TDI 4dr
2005 VW GTI MKIV - SOLD
See, I had noise with a portable so I concluded it must be the 5V that was noisy. How will you ground the mobo?
Where do you draw you IGN line for the M1-ATX from? I pulled mine from some fuse using a fuse tap. If that line also fed the 5v regulator it would shut the amp down right away while the computer is doing standby or hibernate.
I guess I'm being picky, but it bugs me knowing the sound is there all the time even if a moving car and music mask it.
My worklog.
Status: VM GTI sold, got out of the CarPC tinkering hobby, but I still think about getting back in.
I will just solder a cable to one of the holes that you would put a mounting screw though, since i have a plastic case they arent getting grounded like it would in a metal case. ill run thatcable to the factor ground point or the ground running to my PSU.
Right now i havethe 12+ and IGN connected since im testing with a 12V socket. but tomorrow i will splice into the factory radio wiring and take the power from there.
Im the same way, but i want to try grounding stuff first since i dont hink the problem lies in the input.
1990 Jeep Cherokee
2000 VW Golf TDI 4dr
2005 VW GTI MKIV - SOLD
I have this idea that adding 5V to all three conductors coming from the headphone jack will make things more "right" and reduce noise. So, how do I go about it?
Here's a quick drawing:
I have to add a capacitor to each conductor to protect the headphone jack from the 5V flow, fine. But If I tie the same 5V feed into all L+, R+, and gnd, won't the signal from those lines all bleed together?
My worklog.
Status: VM GTI sold, got out of the CarPC tinkering hobby, but I still think about getting back in.
Ok i gounded the motherboard and it made a BIG diference.
When booting it up there is vitualy no noise, just some hard drive sounds but thats not related to this, and is to be expected on the onboard sound.
1990 Jeep Cherokee
2000 VW Golf TDI 4dr
2005 VW GTI MKIV - SOLD
Great news! I'll try that tommorrow. The thing is, I got the hard drive-ish chatter from a separate audio source when powering the 5V regulator with the PSU (but, it is the same 5V rail used by my laptop hardrive).
Looking forward to your dash piece how-to. nudge. nudge.
My worklog.
Status: VM GTI sold, got out of the CarPC tinkering hobby, but I still think about getting back in.
Grounding didn't help me.
I ran a wire from a mounting screw on the mobo to the negative terminal on the M1-ATX. I'm going to try another audio source again and see if I still hear the noise. If so, then I think I need to take the 12V input into the regulator from somewhere else and control it with a relay.
My worklog.
Status: VM GTI sold, got out of the CarPC tinkering hobby, but I still think about getting back in.
kByrd,
it's called a low-pass filter. Basically, a wire can support an infinite number of frequencies. Now, a DC signal (our 5v) is supposed to be 0 frequency... but there is a chance that other frequencies (specifically, 20-20k Hz) might have gotten into the wire. So what I did was create a filter to only allow really really really low frequencies (so hopefully just 0). I can give you the schematic for that if you want.
profit,
It might be a ground problem. Now, you grounded the case of your carputer? Like with an alligator clip or what?
Here is another update.. while the computer is off (after it starts up I shutdown) and the 5v is still keeping the amp on, there is NO noise! So it has to be a problem with the computer and probably ground!
Any ides to get me closer would be appreciated.
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