Noise in the PDA.

[munecito]

Hello guys.

I have a PDA that I use as an MP3 player in my car. The only problem I have is when I connect the PDA to the cigarrete lighter charger, it starts to make a noise, I know it comes from the alternator.

I'm installing a new cigarrete lighter socket soon to be dedicated just to the PDA and the GPS. My question is: If I install one of those noise supresors in the circuit of the new socket. Will it stop the noise from coming throught the PDA sound output??? or am I crazier than a goat???

Any help would be appreciated.

Will

[mickyd555]

do you mean a whistling noise.........

ive been told you need to put a capacitor across ya altanator, but im not sure how its supposed to be hooked up

[munecito]

Exactly that kind of noise that gets worse when you rev the engine.

I don't know about the capacitor. I was thinking in one of these:

Noise supresor click here

The problem is only when I conect the PDA to the charger. The radio works perfect otherwise

Will

[-Scott-]

That should work for you, but I would have thought a 20A rating is overkill for GPS and PDA. Have you checked the combined current consumption? The 5A version referred to in the link should be closer to the mark for you. 5A is 60W, which is a fair amount of power for electronic devices.

BTW, you'll probably find the unit is a couple of capacitors, with possibly an inductor too. I'd experiment with a few capacitors first. Try an electrolygic capacitor between +12V and ground, at the back of the cigarette socket. Anything with a voltage rating above 12V, anything around the 1uF range (say 0.1uF to 10uF.) 20 to 30 cents each from Dick Smith or Jaycar. Most of them are polarised, and have a "-" sign next to the leg which goes to ground. Drive to Jaycar, spend a dollar or two on a few capacitors, then try them in the car park - just hold them in place (be careful with the polarity!!!) If it doesn't kill the noise, buy the fancy filter before you leave.

Good luck,

Scott

[munecito]

Good thinking.

Thanks for that.

Will

[zooki]

does the pda output the sound to something else or are you playing direct from the PDA? I assume it feeds to an amp or something cause you wouldn't hear it out of the inbuilt speaker.

try plugged into the lighter socket but playing through its own speaker, IE nothing else plugged into it, is the sound still there or is it gone? if it's gone you have an earth loop, you can try to fix it by earthing the ciggy socket to the radio case and unplugging the arial (not very good) or get an earth loop isolator that goes on the rca leads between the PDA and whatever.

pretty common problem with some headunits that have 4 ch RCA thats isolated from each other going into an amp that the inputs arent isolated too

[munecito]

I have the PDA connected to the car radio via male-male 3.5mm stereo cable. The car radio I have has an auxiliary stereo input in the front. When I play the PDA without hooking it to the radio it still gets the noise, so I think the capacitors or the fancy noise supressor will do.

Will

[adam.s]

It's ignition noise.

Try putting some condensors (they are just a capacistor) across your coil, your charging circuit and probably even across the cig lighter circuit.

The noise supressor will just be the same thing but cost a lot more.

If that doesnt work, put varied values of cap's across the cig lighter, varied values will do diff frequency noise.

There is a formula to work out what you need, but I CBF remembering it

[murcod]

The noise reducer in the Jaycar pic will have an inductor inside it (ie. a coil.) An inductor will reduce voltage fluctuations (or "noise") on the +12v line.

I've used a similar item in a vehicle and it worked well. Check your cigarette light socket is earthed well too.