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Need Tips on adding Bluetooth (vintage conversions)

Rob_Feature

Rob_Feature

Rob Feature
Recently I've been really interested in doing conversions of different era vintage radios into bluetooth speakers. I've decided I'm going to do some for my family members this Christmas. The problem is, thus far, I'm kinda flailing around and haven't been super happy with any that I've done. There's so many factors, depending on the unit you're starting with, but I'm hoping you smart folks can help me consolidate my methods and make things work a little better.

Below is a general summary of the way I see the situation right now. There's so many factors to consider, please bear with me:

Type of Conversion
In my mind there's a couple different types of conversions:

1. "Quick and Easy" - Buy an existing bluetooth speaker, rip out the bluetooth module (which contains a small amp) and basically wire it into a gutted vintage unit (potentially re-using the units existing speaker if it works). This is the type of conversion you see all over the internet...and it's not what I want to do. This basically treats your vintage unit as an empty box that you mount a new, prebuilt, solution into. Easy but not good.

2. Bluetooth Addition to Existing Unit - This is really what I want to do and I can't find a good, basic, discussion about best practices or helpful tips. I don't really want to build my own bluetooth module if I don't have to (if that's the best way, I'm open to it, though). There's some pre-built modules on ebay that I can get for $4 that are usb powered (5v) and have line-out (which I can wire directly into, without a plug). I've used these a couple time and they have the features I want for my purposes. But:

The Power Problem
As mentioned I've found these great usb-powered bluetooth modules that are more or less ready to go. The problem? Getting 5v DC (usb) power to the unit without batteries or too many extra huge parts.

This gets more complicated because some units I want to convert are 120v AC (wall plug units) while some are battery powered (boom boxes, etc).

So...this is the biggest thing I haven't figured out: What are my simplest options/solutions for a small way to convert 120v or battery power to 5v dc? Is there a converter out there that can be used for this purpose (and i realize this is probably an either/or...there won't be a converter to use for AC and battery conversion at the same time).

Generally...this power problem is my biggest barrier...and I can't find any consistent (good) answer online on how to do it. So far, I've hard-wired an iphone wall wart into a unit, just tapping it into the AC line in....it's ugly cumbersome, and just doesn't feel safe.

What's a good efficient way to do this? Any links to converters people use for this?

The Line-In Problem
This is more minor and it differs for every unit: If you want to use the built in power amp for the vintage unit, whats the best way to locate a place to tap your bluetooth line-in into the unit? Ideally this lets you use the volume and power on the vintage unit. Is there a general rule of what to look for? (on old units, its easy to just tap into the volume knob, I've found...but most units after the 60s make this alot harder)

Ideally you'd make the bluetooth input an option (ie. you can use AM/FM/Cassette OR Bluetooth on an old boom box for example), but this is sometimes more effort than I want to put in (mounting an extra switch, figuring out where to tap in, etc). So, I'll normally find a unit where I'm ONLY going to use it for bluetooth and just bypass everything else.

Wrap Up
I know this is a big rambling post...but hoping some kind DIYers here can help me orient myself, maybe locate a part or two that will make my life easier, or offer a general roadmap on doing these conversions.

Any help out there? Thanks in advance...

PS: I grabbed a vintage wall phone that I want to turn into a bluetooth speaker for my sister (she has a vintage vibe in her basement and this on the wall would be great). I want to mount a speaker behind the dial somehow. This is just a 'gut it and use the case' project, but it should be a fun one if I can figure out how to do it :)
 
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Rob that seems to be an interesting project. I doubt you'll have difficulty finding a power supply; however you'll need adequate amps.

Will you also add a more traditional subwoofer to the system, maybe hidden in a corner of the room or under a table?

I assume you are going to sacrifice stereo.

Rob_Feature said:
Recently I've been really interested in doing conversions of different era vintage radios into bluetooth speakers. ...
As mentioned I've found these great usb-powered bluetooth modules that are more or less ready to go. The problem? Getting 5v DC (usb) power to the unit without batteries or too many extra huge parts.
...
PS: I grabbed a vintage wall phone that I want to turn into a bluetooth speaker for my sister ... This is just a 'gut it and use the case' project, but it should be a fun one if I can figure out how to do it :)
Click to expand...
 
Thanks for a reply: I'm a little surprised I haven't gotten more feedback on this issue...I figured this would be a common style of projects for audiokarma DIY'ers!

Joe Grane said:
Rob that seems to be an interesting project. I doubt you'll have difficulty finding a power supply; however you'll need adequate amps.
Click to expand...
I'm assuming you're talking about the wall phone project? If so, that will actually be the easiest one. The store called "Five Below" has these little bluetooth speakers for $5. You can literally open them up and they contain a PCB and a speaker and are totally self contained....so you simply remount them into the phone (or whatever else you're converting).

The idea isn't really good quality audio..it's going to sound like a little crappy speaker. It's more the nostalgia "isn't that cool?" factor that I"m going for. It'll look cool hanging on the wall with a little extra bonus of actually doing something :)
 
I agree with your "isnt that cool" factor.

So you need power for the bluetooth speakers.

If you added a woofer somewhere in the room it would provide background music.

Rob_Feature said:
... The store called "Five Below" has these little bluetooth speakers for $5. You can literally open them up and they contain a PCB and a speaker and are totally self contained....so you simply remount them into the phone (or whatever else you're converting).

The idea isn't really good quality audio..it's going to sound like a little crappy speaker. It's more the nostalgia "isn't that cool?" factor that I"m going for. It'll look cool hanging on the wall with a little extra bonus of actually doing something :)
Click to expand...
 
When you say "Vintage Radios" what do you mean? Table Top radios or boomboxes or stereo receivers etc.

I have been asked to do this many times by customers - it is always more difficult to do well, than people imagine - Chris
 
ChrisMarantz said:
When you say "Vintage Radios" what do you mean?
Click to expand...
Yeah, I mean kinda 'anything'. They're all different, I realize, but I've tried to do everything from a 1940s table top to a 60s transistor radio. Mostly I'm wondering how people who do this get power to the bluetooth module, whether it's from 120AC or the on board batteries of a transistor/boom box. Any ideas on how to convert that to the 5v DC that most bluetooth modules will require?
 
Joe Grane said:
Does the bluetooth unit have a power amplifier to drive speakers but only requires 5vdc?
Click to expand...
My intention is to TRY to use the onboard amplification, speakers, etc, to these vintage units, so the bluetooth module doesn't need to drive anything. It just needs to provide a line-out, which I then tap into the input stage of the existing unit somehow.

There are small bluetooth modules that have onboard amps (see my 'five below speaker' comment above), but they're weak and don't sound great.

As far as the power adapter, yeah, I'm aware of bigger adapters...but the goal is to minimize the power conversion so it's small and can fit inside the vintage unit. I want these to LOOK original (no extra power cords hanging out). The best I've been able to do, so far, is use an apple iPhone charger wall plug and just hard-wire that in. That's the smallest 120v to 5v DC method I've found so far.

What I'm really looking for is a version of that iPhone adapter/plug which is just the converter board...so I can then hardwire 120v in and 5v out to that converter board...thereby totally . minimizing the size of that converter.

Does all that make sense?
 
most things that aren't tubes have an internal step-down supply. The trick is figuring out the voltage and where to tap it. Typical arrangement is a transformer, a rectifier, a filter cap, and then whatever else. Ideally a schematic is wanted here but you may be able to fish around with a voltmeter on the supply board. SOme of them are already labeled on the supply board connectors for what the output voltages are.

Inputs are pretty easy if its got a regular analog knob type control. If you get a module that has internal switching, this gets even easier. I've seen those on ebay, no direct experience, but they have an input and an output. When not paired, the signal simply passes through, and when paired it feeds in that source.

https://www.ebay.com/itm/1PCS-12V-2...334723&hash=item3d0a8351d1:g:R5oAAOSw7FRWXPS3

(keep in mind all of this cheap stuff comes from China, so the instructions are a bit fuzzy)

Anyway, find the volume control. It will usually have 3 terminals for mono, or 6 for stereo. The stereo ones are usually built in "layers", like this

FT7FBKAHEQEQWJO.LARGE.jpg


In this pic, pins 1 and 4 go to ground. Pins 2 and 5 are output to the amplifier. Pins 3 and 6 are input from the tuner/tape/whatever. These are what we're interested in. Break the connection between those pins and whatever they come from. Output from your module goes to the volume control pin. The original connection goes to the input on the bluetooth module. If this is wired properly it should auto-switch sources when you pair up the bluetooth.


If you're working with a battery power unit, small supply modules can be had that will take a wide range of input voltages and output a specific one.

https://www.ebay.com/itm/DC-DC-Boos...200128?hash=item23bd9f7800:g:jq4AAOSwCA1c7QAr

input is 3.3 - 32v, output is adjustable across that range. Just set the output to what you need and feed it with whatever is available. This will also work fine off an internal supply voltage that is not what your bluetooth module requires.


mind you I've never done this myself so its mostly speculation but in theory it ought to get you where you're going for small money and without completely gutting what you're starting with.
 
gadget73 said:
mind you I've never done this myself so its mostly speculation but in theory it ought to get you where you're going for small money and without completely gutting what you're starting with.
Click to expand...
This is a really excellent starting point...thank you!!

As mentioned, power is my biggest problem and you offer an interesting idea: Are you basically saying: "as long as it's a solid state radio, it will be converting AC->DC in there somewhere already...so tap off the DC side of things rather than trying to convert the AC"? That makes alot of sense...I think I didn't really think of this because I know I can't really read a schematic, and I was never sure where to start probing for the DC....but this sounds like an excellent approach. Buy one of these "step-down" converters (that looks like it'll take a wide range of DC input (?) and find an existing DC supply point inside the unit...then we're good to go.

That all seems great in theory :)

The other problem is going to be the volume knob. The only vintage unit I've encountered, thus far, that has a knob with this style is an old 1940s tube radio. Every other unit has a solid-state type dial of one sort or another (think transistor radio from the 70s)...and accessing those pins isn't that straightforward, I don't think. I'll probably struggle there unless there's a similar procedure of identifying input for these types of volume pots. (?)

The pass-thru bluetooth module would be gold. I wasn't aware of those before...I love it because it means you can retain all the same functionality in the unit, and this would be an add-on. Excellent link there, thank you!
 
I also just realized I may not even need a power converter...the bluetooth module says "Wide voltage conversion module Bluetooth 7v-30v..." which I'd assume means it can accept any value in that range. There's almost certainly something available in that range inside the unit (I'd think). It would depend, I guess...
 
yes, use the internal supply. If you need to convert the internal supply to some other voltage, use a buck/boost converter to get you there. If its something that can plug in or run on batteries, the internal supply will be basically whatever the total battery voltage is, probably in the 6-12v range.


I was sort of looking into those boards in case I wanted to add bluetooth to an old car stereo. I was figuring on removing the tape mechanism and mounting the BT board in that space. The pass-through function would let it integrate neatly without the need for added switches. I never did it because I own nothing that actually uses BT.


Depending how the units are built, the volume may be on a board with a wire harness coming from somewhere else. If you can identify the wiring you may be able to just clip the wires in the harness and feed in signal there. Absolute worst case, a razor blade will sever traces on the board and you can solder things in that way. I prefer to not hack boards when possible though.


with old tube radios, be careful of the voltages. Most of them have high voltage DC supplies in the 130-400v range.
 
gadget73 is right, This is probably your best route. I tried an AC adapter coming from the mains in a few projects. One of them gave me a ground loop I couldn't easily get rid of. Solved it by using existing 6V DC tied directly from a transformer tap. Don't know why that was my last resort, could have saved myself LOTS of headaches, but live and learn.

Rob_Feature said:
As mentioned, power is my biggest problem and you offer an interesting idea: Are you basically saying: "as long as it's a solid state radio, it will be converting AC->DC in there somewhere already...so tap off the DC side of things rather than trying to convert the AC"? That makes alot of sense...I think I didn't really think of this because I know I can't really read a schematic, and I was never sure where to start probing for the DC....but this sounds like an excellent approach. Buy one of these "step-down" converters (that looks like it'll take a wide range of DC input (?) and find an existing DC supply point inside the unit...then we're good to go.
Click to expand...
 
Thanks @Vintagecheap , it's nice to hear someone who's actually done this (and thanks for making the mistake before I do ;) )

I ordered two of the bluetooth boards that you linked from ebay @gadget73 so I'll report back once I get them and try to do something with them!
 
I'm curious how they sound. Might eventually join the modern world and get something with bluetooth, in which case the not too functional tape mechanism in my vintage 80s car stereo is on borrowed time.
 
Just since someone might get a kick out of it: Here's a pic of one of the finished projects: The wall phone converted to bluetooth speaker. I wish I had a 'before' pic, it just looked like a crappy grey 1970s wall phone. But I think it looks kinda cool now. I basically ended up gutting the whole inside and installing a fairly ready-made bluetooth speaker (relocating the power switch to the bottom left corner of the phone). It sounds like crap...but that's not really the point. It works and it looks kinda neat.

IMG_1395.JPG

Then here's one that's a work in progress. My grandpa's 1945 clock radio that I'm converting to bluetooth for my mom. In the end, I figured out that finding DC in an existing device isn't worth the trouble (not to mention really old radios like this have no DC), so the solution was buying a couple little AC/DC converter boards off ebay. Then I can just pull the line signal right from AC, and do a separate conversion for the 12v dc bluetooth board that I ended up using. Seems to work well overall.

(BTW: I got to the point of using a separate converter board because trying to pull DC off the radio's conversion was dragging the DC level down so far that the radio wouldn't work, plus the board wouldn't power up properly...so...it was easier to just do a separate conversion off the line signal)

Anyway, here's a pic of that conversion still in progress:
IMG_1394.JPG
 
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gladiator335 said:
That's all very exciting...but I don't really understand what seems to be a problem.
Click to expand...
I guess what I'm trying to do is a couple things: First to keep everything LOOKING original from the outside. So, I don't want any additional cords hanging out the back of the unit. That's a main part of the focus here...so if the original unit has one wall plug, then that's it, I dont want a second plug, which means whatever I put in has to be powered from inside the unit. Most of these units are too small to have a second power cord/wall wart packed inside the unit...so that leads to the main focus: A bluetooth board that fits INSIDE the unit (hidden) and also is powered from inside the unit (integrated into the original power scheme somehow).

Some bluetooth dongles, like, I think, the one you posted have internal batteries...those need to be charged. If we want them hassle free (ie. not taking them out or plugging them in externally every time you want to use them), that means permanent connection to USB....which again means a power supply inside the unit that converts 120v AC to 5v dc. So, yes, simple in theory, but not as easy in practice.

I can tack on anything if I dont care how it looks. But I do...to me, these aren't just a really extensive/expensive way to have bluetooth in something. They're display pieces in a home that look vintage/original (or at least cool, per the phone project), but then have hidden bluetooth functionality.
 
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