I have bought an AUX-input from http://www.bortesi.it/interfacce-aux.htm This module works greet. After plugging in, the radio has cd and.. cd changer. I have the HP 2210 iPAQ connected for my navigation and my music. When I connect the headphone to the AUX input everything is fine.... until I connect the 12V for charging the iPAQ battery and the GPS antenna for the navigation. When I power the car you will hear a very high frequency noise and a rubbish noise. It's getting worse when you break. (Also when you stand still and break) I don't have the noise when I use a 12V dc supply on the main. I don't have the noise when I plug in the 12V socket with only the ground connected. I can make the rubbish noise go away when I plug in the RCA plug in the AUX input with no ground. (Only the signal on the sound) I have tried all kind of things but I think I have to use a dc-dc supply to make a good dc voltage for the iPAQ. Or is the DC from the back of the radio better? Does anybody have a solution? That cost not the same as a new car. Andrew
Probably I'm the only one. I have just tried so other things. But still the best result (no noise at all) to use a 12v DC to 220V AC converter. Then an adapter from 220V AC to 12DC again. The pictures are from the 12V socket on the bottom of the dashboard. Cheers Andrew
Thanks for your reply, I have to try one at a car shop, but the second picture with the 2,5Khz block wave doesn't look nice when you hit or release the breaks. And the noise thought the speaker is only when I connect the 12V plus. No noises with only the ground connected. Andrew
I had the same problem with my MYFI XM portable radio. Sounded great until I plugged in the car adapter. I bought andinstalled the XM Radio module from Coastal and now no hum, but it's powered by the radio instead of the 12V accessory. ---Kent
Thanks Kent, I have looked at the site of http://www.coastaletech.com/new_page_6.htm but I don't really understand if the sound goes in the radio by antenna or an other input. But I have been to the Toyota dealer today but he was not so interested in my problem. They didn’t have this problem. (But they don’t put in any other radios in there) I was now looking for a lay-out of the pins of the connectors on the back of the radio. (non-jbl) That I can try the 12V from the radio. I think it should help. Can you see what wires you are using for power? Cheers, Andrew
The 12V sockets just don't have any good power filtering on them. A simple low-pass filter should clean that up. Most electronics designed to work in a car can handle that sort of thing, but if it worries you, install a filter. Even just a capacitor in parallel across the + and - lines should filter a fair bit of that out. If that's not enough, search online for a low-pass filter, there are a ton of schematics out there, and build one for some low frequency like 50Hz, there are probably some out there to filter hum from an AC line voltage. That would get it done. Heck, you can probably buy some pre-made for that. The XM radio kit mentioned connects directly to the car audio system and is controled with the touchscreen. No FM modulation on the output signal. It's a good setup if that's what you want. I have no idea what the pinout is on the radio connectors though.
