Blaupunkt Bluetooth Adapter

[martin.stafford]

A while ago I bought a Blaupunkt Frankfurt US to replace the modern stereo in my car. I contacted a couple of people who made bluetooth adapters and waited months for a reply. After a while I thought it can't be that hard to make my own...

The Frankfurt has a 6 pin din plug on the back for attaching tape decks etc. Pin 1 is output from the tuner, pin 2 is input to the amplifier and pin 4 is unswitched 12V. There’s a white cap in it by default which bridges pins 1 and 2. A Bluetooth adapter can easily be added without any modification as long as it can pass through an aux signal.

I scoured AliExpress for suitable Bluetooth modules with an Aux in, Line out and microphone for hands free that would run on 12v. I bought about 6 of them as they're only $5-15 each and there's almost no information on their features other than a picture. The best one I found is an LN-BT02:
https://www.aliexpress.com/item/3268...5da34c4dmPHfEJ

This one turns on and passes through the Aux input by default. When you start playing music it switches to that. When you stop the music it switches back to Aux. The hands free seems to work but I have pretty low expectations on the quality. There's some buttons but I don't plan on hooking them up, just control it from the phone.

I also bought some 6 pin DIN plugs from AliExpress and wired one up to the bluetooth adapter. My Frankfurt is mono so this is wired for that. I assume the stereo units have a plug with more pins and a similar cable can be made.

blaupunkt.bluetooth.png

I've tested it on the bench and it works great. Next step is to 3d print a case and install it in the car. I'll update on that later.

[Paul W]

Great project Martin, have this on my to-do as well. I'd be surprised if you couldn't find a case you could use @ Jaycar, not as if it'll ever be seen.

[pocketscience]

That's pretty neat. For my 993 I took an Apple Airport Express wifi access point (which has audio out capabilities) - removed the 240/5 step-down and replaced with a 12/5 step-down. The car now has a wifi bubble that I can connect to to stream via AirPlay - and if you config the Wifi connection correctly (basically remove the gateway address) the iPhone automatically falls back to 4G so you can still access the internet (for streaming eg) even though you're connected to a Wifi AP with no internet connectivity. Has worked great for years and was planning to do same for my 901... but you've got me thinking now...

[martin.stafford]

I took Paul's advice on the Jaycar case (HB6016). Went through 3 of them trying to get the button holes right.
LN-BT02 came with all the cables, I just shrink wrapped them together before attaching the plug. Cut off the microphone wires and connected them to a 2.5mm jack.

[e72phil]

Will this work for Apple iOS and Android ?

[martin.stafford]

Yeah, works just like other hands free devices like a headset or car.

The reason I bought a number of different modules was to try and find one which would work best without any interaction. I added the buttons to the enclosure just in case I need them, but I plan on hiding it up behind the stereo and not touching it. This one automatically connects when the phone is in range and automatically cuts in on the radio when the phone makes noise. It doesn't seem to make a ringing noise on an incoming call, but the call audio is routed through the radio and the microphone jack. You use the controls on your phone as you would with a headset.

[martin.stafford]

Finally got around to getting the brackets to install the Frankfurt. Hard to find and pricey but this kit had everything and worked well.

https://www.koenigs-klassik-radios.de/en/trim-plates/blaupunkt/blaupunkt-radio-installation-kit-for-porsche-f-modell-911-912_33152_5148

The bluetooth works great. The hands free works but I’m told I sound a bit muffled.

[pocketscience]

I followed your lead Martin and did the same, but I didn't bother with the hands-free setup. If I'm driving people can leave a voicemail. The BT units works great, and auto connects (iOS) perfectly as you mentioned - the satisfying little beep through the radio lets you know it's ready. I'm actually going to remove the Wifi setup from my 993 and put this in it also. Thanks for your efforts in researching this!

[reedminor]

Ingenious .. well done.

how much do you actually use it though….. are you really wanting to use your phone when driving the 911?

jr

[pocketscience]

From my perspective it's just for music... and it's better than any other solution out there in that regard. I've also installed a Rennline phone mount, but modified it to work with a Magsafe iPhone wireless charger. So I have zero cables hanging around now for power or audio.

[martin.stafford]

Yeah, I use it for music.

The head unit I replaced had hands free so I thought I might as well leave the microphone in place. It's never been practical in a car that noisy though.

How did you wire up the charger Gavin? I've been thinking about making some kind of magsafe charger ash tray replacement but your option might be easier.

[pocketscience]

I installed a panel-mount USB socket under the dash that's hooked to switched power. The USB cable runs from that to the Magsafe charger that's mounted on the Rennline phone mount. The Magsafe has the same size ball for the socket on the Rennline mount - so replaces the magnetic mount in the Rennline kit.

USB socket: https://www.jaycar.com.au/under-dash...ocket/p/PS2016
Magsafe charger: https://www.ebay.com.au/itm/19389895...r=494112566501
Rennline mount: https://www.pelicanparts.com/catalog...RENN14_pg7.htm

The Magsafe charger holds the iPhone very solidly.

The Rennline link above is for the RHD version - which is designed to attach to the fuel gauge. All the pics and video on Pelican show the LHD version that mounts to the clock. The RHD version will attach to the clock if you want, but access to the ignition switch is slightly impacted. I wanted it on the clock, but eventually shifted it to the fuel gauge and am happier with it there.

[reedminor]

very good - well done....

Interested in this from a bluetooth viewpoint - music is pretty pointless for me when driving the 911.... I have the Zuffenhausen 6 piece symphony to listen to instead!

How much did all of this cost? Also - could an electrically challenged (me) person make this? Or would I be better off buying one from experts such as yourselves?

Justin

[pocketscience]

The trickiest part of it is soldering the DIN-6 connector to go into the back of the radio. I actually used a Commodore-64 serial cable which made it super easy. Most people probably don't have C64 serial cables laying around anymore..

The BT module itself is only $10-12 or so.. and that's the most expensive part...