Stereo phono plug to 2 RCA schematic

Posted by: wfaulk

Stereo phono plug to 2 RCA schematic - 10/04/2002 11:28

I was thinking about hardwiring the aux in connectors on my sled to a phono jack mounted in my car, but I can't seem to find an appropriate schematic anywhere. I realize that the RatShack could probably sell me a cable that will do that without me needing to deal with it, but I'd rather get a mountable jack, and that won't be possible with their cable (of course, it now occurs to me that I could get such a cable and cut it open, but I've already typed this much now).

Can anyone point me to such a schematic? It should be quite simple, I imagine. I just don't know how to go from the separate to a shared ground.
Posted by: genixia

Re: Stereo phono plug to 2 RCA schematic - 10/04/2002 11:35

In all probability, the 'separate' grounds of the RCA jacks are actually common in the empeg anyway, so joining them (or only using one) should not be problem - but you should probably get pca or altman to confirm this first. If they are not, then you could probably connect them to a common point using a resistor (1k should be fine), and using that common point as a shared ground.
Posted by: tfabris

Re: Stereo phono plug to 2 RCA schematic - 10/04/2002 11:40

Right.

Outer sleeve = RCA grounds (common).

Tip and Ring = Left and right positive.

Don't know which is which for the tip and ring, though. Anyone?

Also, you might want to have a defeatable chassis ground on the sleeve to compensate for different ground loop issues depending on what device is plugged into the jack.
Posted by: wfaulk

Re: Stereo phono plug to 2 RCA schematic - 10/04/2002 11:40

So that would be one resistor for each separate ground, or join the separate grounds and put a resistor between that common point and the common?
Posted by: wfaulk

Re: Stereo phono plug to 2 RCA schematic - 10/04/2002 11:42

I can figure out left and right by trial and error if I can't find it elsewhere. (Thanks, though.) But I actually had another project where I wanted to do this where I couldn't join the grounds or I'd get this weird crossover between the channels. And now that I'm doing it again, I might as well figure out what I did wrong the first time.

Edit: Supposedly, tip is left and ring is right. I suppose that works out well with Right == Red == Ring.
Posted by: genixia

Re: Stereo phono plug to 2 RCA schematic - 10/04/2002 11:54

The first ---- but Tony has confirmed that you can just join them together and not worry about any resistors.
Posted by: tfabris

Re: Stereo phono plug to 2 RCA schematic - 10/04/2002 11:56

Well, I'm only assuming that they're joined. I don't see why they wouldn't be. But I could be wrong.
Posted by: wfaulk

Re: Stereo phono plug to 2 RCA schematic - 10/04/2002 11:58

But it wouldn't be wrong to do it that way just to be safe, right? Especially considering that a pair of resistors costs next to nothing.