Fenris

ok Thanks audioguru!!!! I"ll try that!!! it makes sense too :) you guys really have some expreience!! i totally neglected that option! Hey Sukhbinder My mp3 player is a Thomson, it has 256MB internal and an mmc slot i use a 512 MB card, i use it as a pendrive too its really handy and sinice its migration in my car i only use the car cd-player when its batt is flat thus the PS hehe, i think i know your mp3 player model and its really cool :D. I'll let you know hoe the shielding test goes!!! wish you a good day!!

Hey Sukhbinder thanks for your reply, the screen is an lcd and it doesn't chage colour, and it isn't backlight eather. but il do a continuity check as you suggested!! THANKS!!! ;D Hey audioguru, i think you could have a point there!, could you be more specific please? I had tried powering up the mp3 player ps from the same ground and 12V the amplifer uses but i still got noise! what do you mean exectly please?? could i try useing dual ground?? I mean use the batts + & - to power the PS, and then ground the audio shield out of the mp3 at the amplifier ground??? You guys are really great!!! Thanks for your time!!!!!! :D

Thanks for the welcome Ante! Well i didn't actually think of that, but the car's earth is the -ve batt terminal, and i took power directly from the battery for testing. ??? could you please explain ur point in more detail please!! Just for the sake of completness the amplifier has 2 power in lines, 1 is just used for identifing the key in igintion, the othe is the power drain, and the other is ground! i didnt avtually ground the boy of the amplifier as i asuumed it would be internally grounded, the amplifer is fed via its low signal input by the mp3 player wish on batt works perfectly but when i use my PS added a noise factor, the PS takes power from batt + and -. I really cannot figure the problem :(

Hi there! I'm an electrical engineering student, and currently i have a problem in my car, some time ago i installed a majestic amplifier so that i would be able to use my mp3 player in my car, i built a custom speaker switch so that I'm able to still use my car cd-player when I'm not useing my mp3, now everything works a charm till recently i decided to power the mp3 player via a voltage regulater i built, the voltage regulator (used an lm317 + capacitors) works fine its a VERY clean (checked it with a CRO too) 1.495V output (mp3 works with 1.5V) now when i used it to power up my mp3 player i got noise as soon as the mp3 player switched on, the noise is a constant huxx and high pitched at times too!! whist it works great on the 1.5 battery! i tried checking the power-supply + mp3 player with my home speaker amplifier and it worked fine!! recently i even added an L7800 to stabilize more the input voltage before adjusting to 1.459. so I'm guessing that the problem is either in a variable voltage from the car batt (which i checked and its a clean 13.04V) or else my car amplifier lacks a suitable input filter??? any help??!!