Internal bluetooth receiver for transistor Beolits

[MrRoast]

Let me first start by clarifying that I’m no electronics expert – and so there will likely be some fundamental things I’m not accounting for in this post, however, I’m hoping that someone can help me achieve what I’m trying to do!

So… I have a fondness for Beolit transistor radios which comes from growing up with one in the family home, and have acquired a few over the years since.

A year or so ago I had an idea of attempting to put together a bluetooth module from off the shelf parts that I could install (but be reversible) within the body of a Beolit with an external source input (a Beolit 1000 for example).

After a period of searching and trial and error I created a rough solution which sort of works ?

– a small step down power supply converter (from 7.5v to 5v) connected via the on/off switch (so the bluetooth board only uses power when the radio is *on*)

– this then feeds a 5v bluetooth 4.1 board (took a while to find one that powers up in receive mode!)

– the audio output of which is connected to the corresponding DIN input pins

Well that’s the theory – however, when I tested it on a Beolit 600 (using internal D cell batteries) as soon as I initiated streaming the sound from the radio just died away. Again I mention I’m not an electronics expert but I’m guessing that the current that is being drawn is too much to power the actual radio in addition to the ps and bluetooth board.

I’ve subsequently tried a Beolit 1000, powered with an external 7.5V 1000mA DC input, and this successfully allows me to stream from my iPhone and hear the music. Success? Kind of, however, I’m getting *noise* in the background of the audio signal. As this is absent if I power the ps and bluetooth board via an external source I’m guessing it’s related to how/where I’m pulling the power from internally.

I’d love to get this all working and give me a new way to use my old Beolits but could use some sage advice! Where am I going wrong? Is this ultimately achievable?

Thanks!

 

[matador]

Hi.

I’ve tried in the past to “bluetooth” various things: a Beosystem 10, a Beolit 707 and a Beocom 6000 at least. All this is documented on the old forum.

The Beosytem 10 ended up being airplay-ed.

For the 707, I use an USB receiver and a slim powerbank. It did work and was “useable”.

But the thing was that the sound was very bad.

– Dumb assumption – I believe the speaker was meant to emphasis common frequency from radio or music from that time and now when you feed it with whatever modern sound (not music, sound) it just sounds hollow. Absolutely no benefit appart the pleasure of the game.

Anyway, now what I want is to find a cheap, dead, not reparable 707 and a Beoplay A2 in the same condition and just tuck the last into the first.

For what it worth the BS10 Airplay attempt ended up the same: sounds hollow, flat, better find a bargain con a Beolit 12: just what I did !

Hope this helps.

[MrRoast]

Thanks Matador – I’ll have a dig around the old forum for your posts, I think I remember seeing the Beocom 6000 thread.

I know the easy thing would be connect an Airport express to the DIN in (as I did with my own BS10 years ago) but I’d like to have something self powered and ‘internal’.

It’s less about the sound quality and more the ability to make something 50+ years old still relevant today – and less dependant on software than today’s B&O!

[matador]

MrRoast wrote:

The ability to make something 50+ years old still relevant today…

I understand perfectly. Unfortunately, with the end of the FM band and the short broadband of the receiver (“my” stations are past 105 MHz) the only relevant use I’ve found is decoration. Hope you’ll find better to do with it.

[MrRoast]

Here’s hoping!

I read you 3D printed slider buttons for your 600 – I don’t suppose you would mind sharing the file? I have a 400 missing all its buttons!

[matador]

MrRoast wrote:

I don’t suppose you would mind sharing the file?

Of course I would! Weird it didn’t did it already…

Here it is.

[matador]

It’s the slider knob…

[MrRoast]

Fantastic – thanks!

[artig]

I don’t know if they are legal everywhere, but you can buy small, fairly cheap, BT receivers that transmit a weak FM signal with a range of only a few metres. They need a 12V supply since they are most often sold for use in older vehicles. It’s many years since I’ve tried one, before the time of BT, so it needed a wired signal in. If it works it wouldn’t need any Beolit modification at all.

[MrRoast]

Thanks artig – I used to have something similar for my iPod back in the day, however, I’m looking for a solution that doesn’t rely on an external power source.

[Dillen]

Note: Some Beolit models have positive ground.
This can be a problem in that most BT modules have common grounds for power and signal,
thereby shorting the Beolit power if used on internal power.

Martin

[MrRoast]

Thanks Martin – I’m guessing that’s why the Beolit 600 ‘dies’ when bluetooth streaming is initiated when running on batteries.

The Beolit 1000 works (so assume not positive ground?) – but there is noise that isn’t there when the module is powered separately – could this be ground related?

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