Car Audio CD Changer A/B Switch

Hi

First post here...

I want to add another CD changer into my car audio system. I currently have a Blaupunkt headunit and an in-dash 5 disk changer. I want to add an additional trunk mounted 6 disk changer. The problem I have is that my head unit will only accept 1 changer at a time so I would like to add an A/B type switchbox in to the circuit. I'll need to switch the following circuits:

My questions would be:

- Switched +12VDC
- Bus - In
- Bus - Out
- Bus - Ground
- Line In - Left
- Line In - Right
- AF - Ground

The basic circuit would look something like this:

**broken link removed**



1. Can I use two 4PDT signal relays suited to 12VDC usage, like the Aromat PT#: TQ4-12V? Or should I use a power relay like the Aromat PT#: SP4-DC12V?

2. Will the magnetic field on the relay coil affect the audio signal at all?

3. If the relay won't work well could someone please suggest something that might?

4. This system is in a '00 VW Passat and it seems that the VW OEM modular connectors are identical to the Blaupunkt head unit and changer plugs. I would really hate to cut my car's wiring harness to install this switch so I was wondering if anyone knew of a source of male and female connectors of this type? I'm guessing they're some sort of German DIN standard connector -- or maybe it's that Blaupunkt is Bosch, and Bosch is a major supplier of OEM electronics and electrical to VW.

I've had a bit of experience with some minor electronics projects using the basic components like transistors, resistors, diodes and LEDs for my car audio system, but I've never run an audio signal through a relay.

Any advice would be greatly appreciated.

Chris

Any thoughts on this? Relays okay for audio signals?

seebee63 said:

Any thoughts on this? Relays okay for audio signals?

Click to expand...

Relays are fine for audio signals.

Using relays to switch between the two players should be fine, if a little 'crude' :lol:

Nigel Goodwin said:

seebee63 said:

Any thoughts on this? Relays okay for audio signals?

Click to expand...

Relays are fine for audio signals.

Using relays to switch between the two players should be fine, if a little 'crude' :lol:

Click to expand...

Thanks for your response.

What would be a less crude way to do this? I'm always open for better ways of doing things – even if it is more work. I have worked with simple circuits before using basic components so I may be able to tackle it.

seebee63 said:

What would be a less crude way to do this? I'm always open for better ways of doing things – even if it is more work. I have worked with simple circuits before using basic components so I may be able to tackle it.

Click to expand...

You could switch it with CMOS switch IC's, but it's a LOT more complicated than relays, and probably doesn't do as good a job!.