(I have a few years of fooling around with arduino projects but by no means am any kind of expert)
So I have this wonderful old Zenith table top radio that actually works... sort of. But don't really ever use it. But I am thinking about incorporating a system that would allow the playing of mp3 files that contain radio programs from the 30's and 40's(The Whistler; The Shadow, The Big Story, etc) (I have no experience with mp3 files).
I have considered a few different approaches but the best one would be to use the off-on/volume switch, and the tuner dial, and the speaker for their original functions.
Another requirement is... I want to be able to replace the original chassis back so as to appear these changes were never made.
Currently I am thinking about using a potentiometer (connected to the tuner dial) and connect it to an Analog pin, then determine which “station” from the value the ADC returns for a each “station”. Of course, modifying the off-on/volume switch for the “off-on” part would be easy but not sure how to go about incorporating the “volume” part. Optimally I would also like to use the original speaker.
As an example: I see there are several different kinds of mp3 players on Amazon. Any suggestions about which one might be a good choice for this application? I am guessing that I could put multiple programs on a single player then select them, based on the ADC value...
Where would I look for some sample code?
I have made a creepy radio Halloween prop that plays old scary music and bits of shows . The mp3 player I used was the DFplayer Mini using DFPlayerMini_Fast myMP3 library .
Simple approach may be to inject the audio signal from an MP3 player headphone socket into the top pin and ground on the volume control of your old radio via a small capacitor.
Tune the radio off any local station and go from there.
How many turns of the tuning knob does it take to go from one end of the tuning to the other? A 10-turn pot connected directly to the tuning knob might be an option, otherwise you would need some way to drive a regular pot from the tuning dial/capacitor. If you could find a wheel of similar size to the large pulley on the tuning capacitor a friction drive to a pot would probably work.
If you don't mind disabling the actual radio, you can disconnect the wiring to the volume control and wire the volume pot to the arduino, although it may need a bit of cleaning after all these years. Don't know if it's still available, but there used to be cleaner specifically made for potentiometers, they do get oxidized and sound scratchy over time.
Speaker would be the easy part, just remove the original wires and connect up to the player. May not work too well, the paper cone usually dries out and cracks over time, but if it is unusable it would not be hard to find a small modern speaker that would fit within the frame of the original.
Don't neglect to wire up a couple of white LEDs for the illumination lights.
I would not recommend using the actual amplifier in the radio, lots of high voltage and very old electrolytic capacitors, and apparently no fuse on the AC cord.
Well, I do exactly what you are trying to do, listen to MP3s or PC Sound on a Valve PYE radio from the 1940s, works well and sounds great.
First a warning, some old style mains stuff can have a live chassis, so do not attempt a direct connection to your PC etc.
I built a very low power AM transmitter to which I can plug in output from a MP3 player or PC. This has the significant advantage that no alterations or changes to my vintage radio were needed.
OK guys, thanks for chiming in. Actually, I would love to do something like srnet did However, I now think my post was a bit early in this effort. After posting I spent most of the rest of the day researching a way to make this happen with the level of my skillsets. Of the two required skill sets (1)shade tree mechanical engineering and (2) shade tree electrical engineering, I am a whole lot stronger at the former than the latter. I had forgotten about a project I completed about 15 years ago. I was building a pre-war street rod and decided to drive a modern radio with an analog tuner with the original radio head. Worked out great and since I wouldn't have the faintest idea of how to do some of the things mentioned here, I feel that what I am about to try has a good chance of working.
I just ordered this "tr618" radio. My plan is to order the required gears, sprockets, chains, etc. from the "Robot Shop" to do a mechanical connection between the original controls and this radio.
I will have to remove the chassis of course but I plan to be able to replace it, if I ever want to, without any indication of this effort.
If you directly integrate with the electronics on your existing radio, then ensure that it is of a type that is fully isolated from the mains. Some don't have a high voltage transformer and simply rectify mains voltage. Some have just an auto transformer (which doesn't isolate).
srnet:
Putting an Arduino into an old and still working vintage radio would be sacralige in a way, what next a USB socket ?
I do agree with that, I would be very reluctant to alter the radio if it were actually working. The OP did make the comment that it "works - sort of" without much explanation of the "sort of" part.
I just ordered this "tr618" radio. My plan is to order the required gears, sprockets, chains, etc. from the "Robot Shop" to do a mechanical connection between the original controls and this radio.
I will have to remove the chassis of course but I plan to be able to replace it, if I ever want to, without any indication of this effort
I think that you will find that all the controls and tuning mechanism are attached to the radio chassis, and you will have little more than a wooden case once that is removed.
Once again, thanks for all the advice.
And thank you david_2018 for going to the effort to find the images of the removed chassis.
First, I have pretty much decided not to remove the chassis. And while electronics are not my strong suite I am now making the effort to learn enough to build an AM transmitter/mp3 player. Also "dave-in-nj", as you suggest, I have been thinking about using the presets as you mentioned. Currently they don't work well, some wont move, others don't return, that sort of thing. Might just need to be hit with contact cleaner. I'm thinking I could remove the metal faceplate and find a way to cobble in some miniature micro switches. The only other actual modification I would have to make is to power up the transmitter when I turn the radio on and I could do that with a "TA12-100 Sensor" on the power cord.
OK, I started out thinking I would use Arduino technology but, in the event, that's not what I did. For those of you who posted here, if you are interested in my solution, you can click here to watch a YouTube Video of the project.
