1970 Flirt Pi Internet Radio

This beautiful little "Flirt" transistor radio from 1970 has had a loving conversion using a Raspberry Pi Zero and modern microswitches, and now bangs out internet radio tunes in the bathroom, its dial (and case) glowing brightly from the LEDs of the inbuilt Pimoroni Speaker pHAT's VU meter. It's powered by a rechargeable LiPo battery and all of the original controls have been re-used.

The power switch does what you'd expect, boots up the Pi and points it at the stream for Soma FM's Secret Agent, while the original volume and tuning dials have been upgraded with microswitches and now control the volume. Pop open the battery cover and there's a micro-USB connector to charge up the battery - it's as cute and functional as it was 50 years ago!

This was also my quickest ever Raspberry Pi project - from junk box to bathroom shelf in exactly a week.

In case you can't see the embedded video it's on YouTube at https://youtu.be/d2tF_ky-CLA

Supplies

Flirt Transistor Radio

Raspberry Pi Zero W

Pimoroni Speaker pHAT

Adafruit Micro Lipo

Pimoroni Lipo Shim

2x Lever Microswitches

1x Latching Double Pole Double Throw Switch

Sugru

Jumper Cables

Small Speaker

Step 1: Peeling the Orange

Finding this old radio at the car boot was one of those moments that drives me to hang around the junk sales in all weathers - in this case it was raining and most of the "amateur" stallholders had already left, so the kids & I had a dig through the "rummage boxes" of the house clearance traders just in case. Immediately on spying this little gem I literally snatched it up and held onto it, it was the perfect size, colour and style I've been looking out for. I can't believe its six years since I published my first transistor radio instructable

Later that day I dismantled it - probably the quickest teardown in history, as it had literally one screw and some clips holding it together. The dirty 49-year-old circuits and speaker joined the growing recycling pile but I kept the dials and power switch, intending to make this conversion as faithful as possible.

Step 2: Soma Code

Simplicity was definitely one of my objectives with this build, I didn't want an airplay speaker or a voice assistant, just a straightforward radio playing a single station. I'm pretty evangelical about Soma FM, their stations have literally been the background soundtrack to my life for maybe 15 years now - in fact I remember first listening after reading a recommendation in T3 magazine - which I'd bought to help me choose my first ever mobile phone (A Samsung SGH-A100). I could sing their praises all day but suffice it to say if you like radio with great music, no adverts, no news and great ethics then give them a spin.

Anyway all I needed the Pi to do was load up the stream of my choice and then let me control it with two buttons connected to the GPIO. The code's pretty straightforward and is fully documented on GitHub at https://github.com/MisterEmm/FlirtPi - on boot it opens the radio stream in VLC player, then looks out for a volume button press on GPIO 5 or 7.

The script was set to run automatically on boot by adding..

 @python3 /home/pi/flirt.py &

...to the end of the autostart file on the Pi. Depending on your setup this is either at:

sudo nano /etc/xdg/lxsession/LXDE-pi/autostart

or...

sudo nano /home/pi/.config/lxsession/LXDE-pi/autostart

Step 3: Pi Hardware

For the audio I decided to use a Pimoroni Speaker pHAT - a mono amplifier for the Raspberry Pi. This pHAT is designed to sit on top of a Pi Zero and provide basic audio through a tiny built-in speaker, but I had other ideas.

Rather than connect the pHAT directly to the Pi I soldered in a set of jumper cables to the required pins (after checking out pinout.xyz) - this was so that I could mount the LED side of the pHAT as close as possible to the radio dial, and also so that I could get at the spare pins I needed to add in the button volume controls.

I also soldered a Lipo Shim to the Pi, allowing it to run directly from a small LiPo battery - it's a great power option, but those battery connectors are really small and fiddly - I needed a better way to disconnect the battery for charging than getting out the needle-nose pliers every time, so looked out for other options.

Step 4: Original Controls

Recreating the radio controls was definitely my favourite part of this build - I began with the volume and tuning dials. Rather than going overboard and using rotary controllers I carefully cut off some small pieces off the dials and super-glued them to lever microswitches - that way they could poke through the case and look exactly the same as before, except being clicky now instead of wheely. This works really well and I'll definitely be using the same technique in future builds.

The power switch took a bit of research until I could find one that was just the right size to slot into the power button (even then I ordered 3 slightly different ones, which all arrived in separate parcels, on separate delivery vans, really got my £3 worth thanks RS!). The type of switch was critical - I needed it to be locking (so the power would stay on) but also wanted it to switch the battery into a charging state when turned off. I achieved this using a double-pole double-throw switch, so that when it was "off" it could isolate the battery completely from the Pi and instead connect it to a Micro USB LiPo charger, an Adafruit Micro Lipo.

Step 5: Speaker & Charging

The Micro LiPo charging board was conveniently a perfect fit for the battery bay door, which really made me smile, just the idea of opening up the little door to re-juice the orange, the same way you'd have popped in a fresh PP3 back in the 70s.

Choosing a speaker was next - I tried all of the ones I had lying around and this small rectangular one offered the best combination of size and quality. It was hot-glued in place, and sounded a lot better than I expected when the unit was fully assembled. Soldering it to the pHAT was a bit tricky as it was designed to connect its own tiny speaker via solder pads rather than pins or holes, but with some careful work and hot glue to hold the cables in place it wasn't too difficult.

Step 6: Assembly

With everything connected up & working on the bench it was time to try and fit it all in the tiny case - always a challenge. In this case it was a real exercise in frustration! Because space was so tight I'd had to solder the pHAT's jumper cables directly to the Pi, something I normally avoid but that's fine to do - provided you have decent quality cables. These were not great quality cables (they were very cheap though) - I snapped at least four of them at the solder joint just moving the thing across the workbench.

After some cursing, solder-sucking and resoldering I first hot-glued the Speaker pHAT into the case, so that the LEDs would shine through the dial.. Next I fixed the volume and power switches securely in place using Sugru - mouldable glue that's absolutely perfect for this job. Lastly I hot-glued the Pi Zero in place, and fixed the LiPo battery using a self-adhesive cable tie holder, so it could be removed if needed later on.

Step 7: Funky Shaving

I'm absolutely thrilled with the way this project turned out, it works exactly as I hoped and from the outside it looks and handles indentically to the original, with nothing to give away its modern interior.

It does take a little while to boot up, and in retrospect I probably shouldn't have used the "full fat" version of Raspbian - still by the time the bathroom sink's filled up and I'm reaching for the razor it's usually blaring out the tunes. It's not what I'd call audiophile quality but it's perfect for the bathroom and much better than listening on my phone.

The battery life's great too, I've not used LiPo batteries in a project before and was very pleasantly surprised.

Most of all this little radio feels like a distilled version of what I love, modernising a piece of old tech but keeping true to the original purpose and re-using as many of the features and controls as possible.

My other Old Tech. New Spec projects are all on Instructables at https://www.instructables.com/member/MisterM/instructables/ and on our YouTube channel at https://www.youtube.com/channel/UCRrwSKYBu4N7P6HWZsWJ2MA

More details and a contact form are on our website at http://bit.ly/OldTechNewSpec. and you can find us on Twitter @OldTechNewSpec.

Comments

[curiosity36]

I liked this when I first saw it. I've found an old transistor pocket radio that should be just right, so I'm back to give it a go. I'm assuming there is a Raspbian OS installed on the PiZed that runs the Python script - true? And where is the Python script installed on the SD card. Thank you.

[NeilRG]

Upcycling / recycling projects always intrigue me. I know that I too will someday be recycled. Until then I upcycle myself by continuing to learn new things.

[curiosity36]

I sure like your little retro internet radio. Once I have it working, I'll decide on an appropriate case. In attempting to duplicate the electronics, I am unclear to which GPIO pins the up & down volume switches are connected. Thank very you much for posting.

[MisterM]

That's great thanks! I do really love it and am about to start on another multi-station one using the same method for another room - the Volume Up button is connected between GPIO5 (Physical Pin 29) and GND, and Volume Down is connected between GPIO7 (Physical Pin 26) and GND. You could use different pins if you like as long as they're not already being used, e.g. by the audio HAT. Good luck with your build!

[Alain C.L]

Very nice "toy" that you made, congratulation for your work and warmness on the making of the video, attention to every detail and so on. Great way to bring back to life our old objects of desire or fun. i do that too...

[amaze1]

I love internet radios in every their incarnation and this one is really nice.
How many minute&seconds it takes to boot?

[MisterM]

Too long really - I should've used a more stripped-down version of Raspbian, just timed it for curiosity and it takes 1m15s - about the same time as it takes my water to heat up conveniently!

[amaze1]

So it's a double function device :))

[only1emmapeel]

Where is your accent from? It is positively heavenly. I'm a colonist and love the Brits. I like Aussies except for their accent -- but yours is from somewhere near the Queen and I only wanted to know if there's a name for your specific area's accent, what is it? Thanks so much.

[MisterM]

Thanks! I'm reasonably near the Queen's winter home in Norfolk, but the accent is a bit of a mishmash, originally what's called "Geordie", from the North East of England, but softened by many years living down South and working in jobs where people needed to understand what I was saying!

[only1emmapeel]

oh, COOL!!!! i actually sent your link to a friend in Chatham and she thought you might be ozzie. I knew if you were you'd be a mighty strange one, cos i LOVE your speaking. I could listen to you til the cows come home, and i can't say that about any ozzie (bless them all, anyway! i think it's the crocodiles that put a fear of english into them)

[DorotaM]

Hey, I have a old wooden lamp radio at home, and I wanted to make it work (I would like to add cd room and USB slot but I'm not sure if it will be compatible with any contemporary radio with knobs) do you maybe have some tips and advice?
Thx for any reply :)

[MisterM]

Sounds cool! It's a tricky one, if the FM part of the radio still works you could send digital audio to it with an FM transmitter, or if it's broken see if you can find a modern radio or music player that would fit inside the case. Depending on where you are there are also some kits available like this UK one (https://shop.pimoroni.com/products/pirate-radio-pi-zero-w-project-kit) that give you all the components you need, that you could fit inside the old case. Good luck with it if you decide to give it a go!

[charlessenf-gm]

My grandparents left me an old wooden console radio in the seventies.it was from Baltimore, MD and had the local radio call letters printed in the appropriate sots on the dial.

I had no idea how to 'fix it' so it would work in the new age. In the process, the repairman wound up with it!

Good for you! Imressive project!

[MisterM]

Thanks - that sounds like a great one, I love the old ones that promoted the local stations, I think some of them were even hard-tuned to their frequency. Wish I was your repairman!

[throbscottle]

Fascinating. Why didn't you use the original speaker?

[MisterM]

Thanks - it was a space thing, I needed the Pi to lie flat in the case and the original speaker was just too wide!

[Legerstee1]

Very nice!
And thank you for the instructable!
I did something similar with a tube radio from 1955 with a raspberry and naturally SomaFM!
Perhaps you enjoy it (sorry i did not make a lovely instructable as you did....)

[MisterM]

Hey that's a lovely build, thanks for sharing! Love how you've made use of the original big buttons, and rotary controls too, that's not as easy as it looks! I had an almost identical radio (see pic) until recently, but it was fully working and I didn't have the heart to dismantle it, also huge like yours. Soma FM forever!

[Hardloader]

You've done a brilliant job - thanks for sharing. I'm intrigued as to why you didn't stick with the original speaker, though. Was it just lack of space?