I've been reading about Bluetooth radio's for a while, and decided to build something big. My girlfriend wanted a nice radio for her room. I ended up buying an old radio from a thrift shop, a Fridor 521. The radio had a few defects (volume stuck at 80% and bad signal). Since I wanted to buid in a new amplifier from a computer 5.1 speakerset, I did not need the inside electronics. I tried my best to keep as much of the old elements in tact. This Instructable is not a simple "get it out and throw new stuff in" tutorial. I hope you enjoy reading this article.
Check the pictures for notes, some have them. They help making things more clear
Step 1: What Are We Dealing With?
Since I never worked on a old radio, and had not decided what to use and not use, I first took a look at the inside. As I wanted to use as much parts as possible, I considered my possibilities.
- Reuse of the buttons
- Redo paint/wood
- Use same speaker, with new amplifier
- Stream music over Bluetooth
Step 2: Cleaning the Easy Parts
I stripped down the radio until I separated all the components from it's wooden housing. I ended up with the electronics, front cover + glass, a decorative plate and the knobs.
All the electronics are stored in a metal compartment as you can find in the pictures above. In this step I didn't do anything with it, I will get into that in a later chapter.
Front cover and glass
I was surprised about the state of the glass and fabric. It was a bit dusty, but no big scratches or other kind of damage. I used water and soap to get it clean and store it for later assembly.
As you can see in the pictures the color of the metal was not how it supposed to be. I cleaned it using scouring cream. After a while it came out pretty good so i did a last clean with soap and dried it.
I noticed that 2 of the knobs miss their "gold" cover, but since the knobs are divided 2 by 2 on each side, I was ok with that. If you take a good look at the first picture showing the knob, you can see a lot of dirt on it.
I used my ultrasonic cleaner with a simple solution of water, vinegar and dish soap. A first run did clean a lot (compare picture), but I decided to put them in 2x 10min. The plastic residue on the last picture was removed later.
Step 3: Make Room for New Electronics
As I said before, before people argue about the fact I "destroy" the inner working, there were too much defectives for me to take care of i decided to put a new amplifier in. This is the reason i didn't buy a full optional tube radio.
One of the potentiometers was broken, so I had a good chance of taking a look inside. The first problem I encountered was the difference between mono and stereo potentiometers. The old radio only used a 3 wire potentiometer, but I wanted to use the 6 wire potentiometers from my old amplifier.
I came up with the idea I might be able to use the broken potentiometer as a housing for my 6 pin potentiometer. The picture shows lockbond at the tip of my potentiometer, but I ended up using hot glue instead.
One of the old buttons was used for selecting the radio frequency. This came out to be a great solution for an on/off switch. The picture shows the 2 dials used in this radio. The one in the left is still as is. On the right one I took out all pins, except three of them (I needed 2 for my buttons, but without the 3th one, the middle ring fell out his housing). I think we don't see electronic solutions like that any more, so more reason to keep it like this!
I've added a breadboard to so I was able to connect all the wires (3x6 for potentiometers and 2 for the power switch) to their individual terminal block. Doing it like this I am more flexible placing the amplifier PCB later on.
Step 4: Adding the Buttons
Remember those potentiometers from the previous step? After i finished them like that, I found out I was not able to place them back just like that because they would turn around freely. I needed to mount the potentiometers stuck in place. I went to the hardware store and got myself some threaded wire (M3). And carved a wooden body using my dremel. Wearing protective gloves could prevent you from cutting yourself, like I did...
After I did all my preparations on the first potentiometers it was time for a new challenge. The old radio only used 2 potentiometers, so I had to find a new solution for my last potentiometer (I need one for volume, bass and treble).
The axis previous function was to change the frequency for choosing channels. I used a table grinder to get a nice V-shape to fit my potentiometers notch.
As described in the previous step I wanted to use this one as it is. After putting it back I had plenty of place to solder the wires in place. I used my multi meter to check for resistance to make sure the 2 wires make contact in "on" position.
Step 5: Wires, Wires an More Wires
Pretty straight forward step. The only thing important is to get the order of the wires correct, thats why I marked my breadboard with a 1 and a 6.
Step 6: Preparing the Amplifier and Hook It Up
The potentiometers in the previous steps are the original potentiometers from the amplfier I am using. I desoldered them using my soldering iron and desolder pump. To clean the connections I used a desolder wire to make sure all tin residue is gone.
I did the same thing for the on/off button, line-in socket and power socket (will use that for a small portable bluetooth speaker I will build after this project).
In the next picture you find the power supply for the amplifier. I placed the parts on the old electronic body. I needed to drill a few extra holes.
Soldering wires again
All the places that contained a component, now contains a few wires. I had to make sure the order of the potentiometers was correct. The rest was not that hard. I now ended up with a working amplifier with "new old knobs"!
Step 7: Adding Bluetooth Functionality
Before i get into this i want to thank user Barry_L for his help, explanation and advice regarding Bluetooth chips and how to use them. Check his Instructables if you are looking for places to buy a KRC-96B for example.
For this project I used a KRC-86B. This module operates between 3V and 5V, only problem that my power supply provided 14V. I used a simple USB cigarette lighter as a step down converter to bring the 14V back to 5V. The picture of the cigarette lighter is an indication of the part needed, it is not the actual part I used.
Hook it up
Since it was a bit of a struggle for me to find good examples of how to hook this module up, I drew a schematic to make it more clear.
You can also add some buttons if you want (for next/prev song etc.) check the KRC-96B datasheet for more information. Wires I used are VCC, GND, AGND, OUTL and OUTR, so you need to solder 5 cables.
I found out I had to put a jack plug in the aux out to make it work. I used a cut plug from some old headphones, maybe this note helps some people in trouble.
Step 8: Fixing the Wood and Painting It
My plan was to sand the whole body and oil it. Unfortunately it had some nasty damage on it's upper left corner and had to glue one joint again.
Sanding and filling
In the process of sanding some of the veneer came loose or was so thin at some places, so we decided to give it a paint job. We still wanted to retain it's old look, but some reparations had to be done. I used some filling primer to reconstruct the wood.
My girlfriend wanted to apply the first layer of paint. After that we went into a process of adding paint, sand it lightly, clean it, paint it again. After continuing this process 3 times we are done painting, finally! Curious about the result?
Step 9: Puting It Back Together
While I was enjoying the last steps in the process I totally forgot about documentary. At the end of it all, this one picture tells enough of the process right? I also added 2 tweeters for high tones. For now they are not mounted next to the big woofer, because I don't have the right drill.
Step 10: Final Result!
I am pretty proud on making this project. I ended up with a fully functional Bluetooth radio for my girlfriend. I want one too!
Any feedback, questions or other remarks? Feel free to drop them in the comments!