Question from my brother...........
1998 BMW 740il
OEM navigation 16:9, DVD, MK4, DSP, Navtool for video, Phillips portable ipod DVD player
CDC is Mbus
I don't know much about relays for audio, but I do for other automotive applications.
I need to add an aux audio input to my radio module. For my stereo sound, and I don't want FM modulator, tape adapter or any other cheap ways like that. BMW makes a BM53 radio and that has the AUX inputs, this is an upgrade from my radio module, but don't want to spent the $400 just this minute for it, BUT I do need it for other stuff at some point.
I have a diagram on adapting my current set up, but don't understand it. Do I need dual post 12v automotive relays? All the ones I have seen have 4 or 5 prongs on the bottom, are they the same? Also they all have # on them like 30,85-90, are they all like that? This is a link to the same set up I need to do. I have all the stuff, I just don't understand the wiring, at least the wiring to the 12v relay. Can someone make this easy for me please....
http://bimmerboard.com/forums/posts/133975/
Here's a pic of a relay...
5 prong
http://www.the12volt.com/relays/relays.asp
Replies (5)
swez on 08/17/2007 13:08:47
In this case, a pair of SPST relays is all what is needed. (One relay post for each audio channel... L & R)
Looked at that schematic link and am trying to figure out the signal pathways. But w/o pin callout on the relays, it a bit more difficult to follow the paths.
As I look more at this design, it appears that a pair of SPST relays are used. (5 pin) Pin #'s 87 & 87a are pathway taps for choosing which signal source is used when coils are energized or not.
In the coil off position, the CD changer is the default unit and tapped to pin 87a for each relay. When the coil is activated by the toggle switch, the solinoid pulls the contacts to activate pin 87 which is connected to the A/D converter that activates the AUX input circuits.
That's how this circuit seems to work. The D/A converter is probably a combination of OP amp and D/A switching controller. This converter needs a 9 volt DC power supply that can deliver 250mA's of current or higher.
http://www.radioshack.com/graphics/uc/rsk/Support/ProductManuals/1501242_PM_EN.pdf
Hope that helps,
Swez
SQLThump on 08/18/2007 00:26:21
RIght on Swez. All of this goes over my head, so I will have him check it out when I see him next.
swez on 08/18/2007 08:58:43
Hehe, took me a while to piece it all together too. Lack of lables on the relays had me doing things longhand too.
Swez
SQLThump on 08/22/2007 05:20:09
I thank you SWEZ for your help.... I just couldn't figure it out...
swez on 08/22/2007 10:31:04
It took me a while to piece things together on that diagram too.
Frankly, if you cannot get $50-75.00 + parts out of the deal, it's not worth the bother. From what I see here, the relays are cheap, but not sure about the RS D/A converter and all the splicing and wiring needs will be time consuming. That is, assuming the circuit design has been tested by others and proven to work.
Swez
1998 BMW 740il
OEM navigation 16:9, DVD, MK4, DSP, Navtool for video, Phillips portable ipod DVD player
CDC is Mbus
I don't know much about relays for audio, but I do for other automotive applications.
I need to add an aux audio input to my radio module. For my stereo sound, and I don't want FM modulator, tape adapter or any other cheap ways like that. BMW makes a BM53 radio and that has the AUX inputs, this is an upgrade from my radio module, but don't want to spent the $400 just this minute for it, BUT I do need it for other stuff at some point.
I have a diagram on adapting my current set up, but don't understand it. Do I need dual post 12v automotive relays? All the ones I have seen have 4 or 5 prongs on the bottom, are they the same? Also they all have # on them like 30,85-90, are they all like that? This is a link to the same set up I need to do. I have all the stuff, I just don't understand the wiring, at least the wiring to the 12v relay. Can someone make this easy for me please....
http://bimmerboard.com/forums/posts/133975/
Here's a pic of a relay...
5 prong
http://www.the12volt.com/relays/relays.asp
Replies (5)
swez on 08/17/2007 13:08:47
In this case, a pair of SPST relays is all what is needed. (One relay post for each audio channel... L & R)
Looked at that schematic link and am trying to figure out the signal pathways. But w/o pin callout on the relays, it a bit more difficult to follow the paths.
As I look more at this design, it appears that a pair of SPST relays are used. (5 pin) Pin #'s 87 & 87a are pathway taps for choosing which signal source is used when coils are energized or not.
In the coil off position, the CD changer is the default unit and tapped to pin 87a for each relay. When the coil is activated by the toggle switch, the solinoid pulls the contacts to activate pin 87 which is connected to the A/D converter that activates the AUX input circuits.
That's how this circuit seems to work. The D/A converter is probably a combination of OP amp and D/A switching controller. This converter needs a 9 volt DC power supply that can deliver 250mA's of current or higher.
http://www.radioshack.com/graphics/uc/rsk/Support/ProductManuals/1501242_PM_EN.pdf
Hope that helps,
Swez
SQLThump on 08/18/2007 00:26:21
RIght on Swez. All of this goes over my head, so I will have him check it out when I see him next.
swez on 08/18/2007 08:58:43
Hehe, took me a while to piece it all together too. Lack of lables on the relays had me doing things longhand too.
Swez
SQLThump on 08/22/2007 05:20:09
I thank you SWEZ for your help.... I just couldn't figure it out...
swez on 08/22/2007 10:31:04
It took me a while to piece things together on that diagram too.
Frankly, if you cannot get $50-75.00 + parts out of the deal, it's not worth the bother. From what I see here, the relays are cheap, but not sure about the RS D/A converter and all the splicing and wiring needs will be time consuming. That is, assuming the circuit design has been tested by others and proven to work.
Swez
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