Also ground the computer case in a few spots, mb, ps, etc.
You can get a ground loop isolator from radio shack, but i've never needed one. just ground everything really good
I finally hooked everything up, the Portawattz 300 POWER INVERTER & my Clarion FM200 FM Modulator to my MP3 player... before that I wanted to test the reliability of the FM modulator so I simply hooked it up to a DISCMAN and the quality was acceptable... then I hooked it up to my MP3 and LO AND BEHOLD, I get a lot of NOISE coming out of the speakers...
My bet is that it has something to do with the ground, so I grounded my power supply to an unpainted metal part of my car's body, it was better, but the noise is still there and very noticeable. What should I do? This is the last hurdle to finally get my system working...
Guy Foster - author of FostRF
Car: 1997 Acura 3.0CL
Computer: Pentium 133/16 megs/6.6gigs/Vibra 16C/40x4 backlit LCD
Software: MS-DOS 6.22 -MPXPLAY - MPXF TSR - FOSTRF
Visit my Yamp3 player website (under construction) at: http://www3.sympatico.ca/guyfoster/yamp3
When I installed my FM mod and power inverter, I found that there were 2 sources of noise. One was eliminated when I grounded the PC case to the ground wire on the inverter.
My setup was also humming because I had the FM modulator and the inverter wired in together to the cigarette lighter. To fix it I wired the inverter to the 12v and ground wires from my head unit, and kept the FM modulator by itself on the cigarette lighter outlet.
I don't know a thing about electricity or grounding or anything, but this worked for me.
p.s. I just started my project a week or two ago, but I'll be sure to do a site for it or at least post some pics. By the way I have a 1993 Jeep Cherokee Sport. It's got an athlon 500mhz, 256megs RAM, 13gig HD, SBLive!. The mp3 player is mpxplay in DOS. It's wonderful if you've ever thought about a DOS-based mp3 box. The thing starts playing 10 seconds after I crank the car. Rock. It also has win98 for playing DVDs on the 7" screen which arrives in the mail tomorrow (yay!) I've got my cell-phone hooked in via serial connection so I can dial up earthlink and check my e-mail while endangering lives on the interstate going through downtown atlanta. I was thinking about a GPS but I don't know thing one about 'em.
And another kitten is brutally murdered...
Player: Pentium 166MMX, Amptron 598LMR MB w/onboard Sound, Video, LAN, 10.2 Gig Fujitsu Laptop HD, Arise 865 DC-DC Converter, Lexan Case, Custom Software w/Voice Interface, MS Access Based Playlists
Car: 1986 Mazda RX-7 Turbo (highly modded), 1978 RX-7 Beater (Dead, parting out), 2001 Honda Insight
"If one more body-kitted, cut-spring-lowered, farty-exhausted Civic revs on me at an intersection, I swear I'm going to get out of my car and cram their ridiculous double-decker aluminium wing firmly up their rump."