brian47
Well-Known Member
Many of you will have seen me posting on the forum about using your mobile phone as your mp3 player with whatever method of connection into the vehicle ICE system you've chosen.
Mine uses a hard wired 3.5 mm jack plug and cable to carry the audio while at the same time I have it connected to the power supply using a USB cable and adapter to keep the battery charged.
This has led to a bit of a problem, whether it's a recent "fault" on the phone or it's been present all the time or I've just noticed it, but there seems to be a conflict in the phone whereby the audio cuts in and out which makes things very unsatisfactory.
If I disconnect the USB, the mp3 player works as it should, if I disconnect the audio lead then the charger works as it should. It looks like it could be a problem somewhere with the two earth connections; the screen on the audio lead and the earth on the USB.
Ground or earth loops are a phenomina which electricians mostly don't even consider because to them earth is a safety feature but they are well known to audio and radio engineers as a problem which often manifests itself as a hum, known as mains hum on the audio signals, in vehicles it can also sound like alternator whine and clicking noises and buzzing interference. In my particular case, the trouble showed itself not as the usual interference but as an interaction between two DC circuits, the 0 volts on the charger and the screen on the audio circuit and by using an isolator I was able to "decouple" the circuits from each other.
There are a number of methods of dealing with ground loops, but in most vehicle based applications the use of a ground loop isolator connected in the audio line is advised. This is the method which I have opted to employ with total success. The unit is a totally passive circuit and consists of two small transformers, one for each stereo channel which can pass the audio signals while ensuring that the "earth" wires remain separate. A fully assembled unit will be "plug-n-play", it's just a case of deciding which plugs/sockets you want on the ends of the wires and there's no particular way round to connect it.
If you do suffer problems with trying to feed audio signals from one device to another in your In-Car Entertainment system, whether it's buzzing, clicks or any other kind of interference, for less than a tenner, usually around five to seven quid, a ground loop isolator might be well worth trying.
Mine uses a hard wired 3.5 mm jack plug and cable to carry the audio while at the same time I have it connected to the power supply using a USB cable and adapter to keep the battery charged.
This has led to a bit of a problem, whether it's a recent "fault" on the phone or it's been present all the time or I've just noticed it, but there seems to be a conflict in the phone whereby the audio cuts in and out which makes things very unsatisfactory.
If I disconnect the USB, the mp3 player works as it should, if I disconnect the audio lead then the charger works as it should. It looks like it could be a problem somewhere with the two earth connections; the screen on the audio lead and the earth on the USB.
Ground or earth loops are a phenomina which electricians mostly don't even consider because to them earth is a safety feature but they are well known to audio and radio engineers as a problem which often manifests itself as a hum, known as mains hum on the audio signals, in vehicles it can also sound like alternator whine and clicking noises and buzzing interference. In my particular case, the trouble showed itself not as the usual interference but as an interaction between two DC circuits, the 0 volts on the charger and the screen on the audio circuit and by using an isolator I was able to "decouple" the circuits from each other.
There are a number of methods of dealing with ground loops, but in most vehicle based applications the use of a ground loop isolator connected in the audio line is advised. This is the method which I have opted to employ with total success. The unit is a totally passive circuit and consists of two small transformers, one for each stereo channel which can pass the audio signals while ensuring that the "earth" wires remain separate. A fully assembled unit will be "plug-n-play", it's just a case of deciding which plugs/sockets you want on the ends of the wires and there's no particular way round to connect it.
If you do suffer problems with trying to feed audio signals from one device to another in your In-Car Entertainment system, whether it's buzzing, clicks or any other kind of interference, for less than a tenner, usually around five to seven quid, a ground loop isolator might be well worth trying.
