Audio input for older delco stereos

[buickmastermind]

This was my weekend project for my '89 Electra PA. I hate low quality provided by fm transmitters and tape adapters...

Here is a way to add a line in for the older delco stereos with tape players that internally connect with the 5-wire (orange, white, brown, red, red/white) style. Total cost was under $20 with parts from radio shack. Sound quality is as high as the source.
Switch is used to switch between radio or tape to line in and back. Depending on the model of the stereo the relay will actually fit inside it with the only wires coming out being the one for the switch.
You can use a d-sub 9 pin connector to make the relay/switch circuit disconnectable from the stereo for another $10, but if it comes off only the radio will work (tape deck would be unpowered).

Cut the red, brown, white, and orange wires in a place that you can easily work on them. There will be 8 total wires coming out of the stereo into the circuit. Use a 3' 8-pin network cable for this (compact, twisted pairs, not the only suitable type of wire to use) as it's easy to keep track of colors, and the ground should be run along the side (not inside) the network wire through the 9th pin of the dsub if used and soldered to a point in the chassis. The red/wht wire can stay connected in the radio - the circuit disconnects power supplied to it when you switch to line in. As always completely cover all bare wire or pins with electrical tape or heat shrink.

Originally, the tape deck switches +12v from the red/wht wire to the brown wire to turn the amp to the tape player inputs (orange, white wires). The chassis is a common ground for everything in the stereo. Grounding anything in this circuit to the car body produces a humming noise through the line in.




Soon to come are details for the similar older stock delco stereo that has the blaupunkt tape deck (different wiring to the tape deck) that I use to power my computer speakers. I have been working on a line in for the stereo used in the 91 Regal and the 7-band equalized cd-player stereo as found in 95 pontiacs (among others I'm sure)

[PaulD]

this is quite interesting, lots of people are into integration these days

[buickmastermind]

(won't post images as decreased size...)

Here is the schematic for the blaupunkt tape player. Uses the same parts as the other to build;
1x DPDT switch
1x DPDT relay

Difference is that this tape player has a search feature, hence the extra wires. Instead of shorting to a 12v source to activate the amp, it grounds the yellow wire.








Blaupunkt tape deck:




Next on the list to add inputs to: