Bluetooth in a stock 80s head unit

[gadget73]

A couple weeks ago I mentioned that I had gotten a working Bluetooth solution in a stock radio, and would eventually do a thread. This is that.

Mostly this is going to be a video where I babble a lot but here are some closer pics of things I mention in the video.

The actual modules in use. Bluetooth is an MH-M18. Can find these on ebay, and there are a couple others that look just like it which I'm sure will work just fine.



this is the op amp module

https://www.amazon.com/NE5532-Microphone-Preamps-Amplifier-Rectifier/dp/B0BY5BHKZ1/

Anything with a gain of about 5 that will run from a single rail power supply will work. Output from the BT module is about 0.25 volts peak to peak, the radio needs about 1.2v for normal output level. This one can be adjusted for more gain but stock its fine.

This is the muting board with arrows indicating where the traces get sliced



and the actual board itself with the connections made and the traces cut



Schematic of the CD version



and schematic of the tape version for comparison.



There is no specific schematic for the non-tape version, but I have every reason to believe this would work fine in one of those. There would be the option of using either the CD or tape input, no idea if there is any real advantage to one over the other.



and the video

https://youtu.be/oQAgrl9p7oY

[DerekTheGreat]

Portrait mode video.

Flip the phone over before hitting record, takes about 2 seconds and the video can be watched widescreen, not to mention you can get much more in the frame and there aren't any black bars on the sides of the screen when watching. Or am I the only one who watches any type of video with a widescreen and not their phone these days?

[87gtVIC]

Cool. Thanks for addressing the shielding question I had lingering in my head near the end of your video. Was much curious about how it would work once all buttoned back up in its normal configuration. You aint getting 20' away while driving the car so like you said it should all work out fine.

[gadget73]

yea the phone was going the wrong way but its too clunky to hold, operate, and keep my phone cover out of the way with one hand going that way, so you're just gonna have to deal with it.