The Stovebolt Site Forums The Shop Area The Electrical Bay The Radio Bench FM & MP3 player...new idea...

I've mentioned before that I'm working on an FM radio and MP3 player that could be easily adapted to the AD trucks...the easier the better in my opinion. Not to say it looks like something original to the pickup. It doesn't but with some very imaginative (and probably expensive) work it might be retro-adapted. Truthfully I'm looking for affordable and useful rather than period correct looking. Over the last year or two there seem to have been a few people interested in this and given the abysmal state of broadcast radio these days I can certainly understand their interest. This is the first bit of useful information about the project and if you're interested, please feel free to contact me directly at [email protected]

Below you'll see a couple of images of what I'm currently testing. This is sort of neat, but absolutely no documentation came with it and sadly the seller and I struggle to communicate well. Basically it is a Chinese-made stereo FM radio combined with an MP3 player and amplifier. But...there is reason to believe it (or other variations of this same/similar circuit) may also include bluetooth ability (telephone call reception). This one appears to, but I haven't been able to sort that part yet. Also...and this will be of interest to folks still using 6 volt schemes...it will operate with any voltage between 6 and 12. I have it sitting behind me happily playing a Dutch story (The Cat Who Came in from the Roof) and the clarity and volume are both in my opinion remarkably good. Especially since I am using it with 2 very cheap 8 ohm speakers. The unit was evidently designed to use a small piece of wire as the antenna (for FM reception), but honestly speaking that little wire is a miserable excuse, so I'm now wondering about the possibility of connecting this to a standard automobile-type antenna. And it appears to support power off memory...so that if you were playing a book (as I am) and turned it off it would resume at the same place when activated again. It came with a small but interesting remote control. Once I find a battery for it, I'll know more. The unit seems to produce no heat at all while operating. Oh, and also...it seems to have a recording function. Don't actually know what that would be useful for but it is novel.

What I've determined so far...amperage use is low. It has two channels...right and left and each is 25 watt. It supports MP3, WAV and WMV sound files. The dimensions...about 3.5 inches wide, 1 5/8 inches tall and would require maybe 1 inch of back-side space. This one has failed to successfully recognize the USB stick but it does recognize and play well from a TF card (same as a micro SD card).

The cost of the unit (not including any wiring nor speakers) is very reasonable...being $15 USD each or less and I'm awaiting other versions of this which I'll evaluate (some less expensive and with other functions). Takes a while for them to arrive, you know.

The second picture shows a total of 6 wires attached to the back of the unit. 4 would be for speakers, 2 for power and ground. No connection for memory "keep alive"? Power output to the speakers would be way down unless they are using some kind of on-board voltage booster to get higher voltage for the output circuitry. The good part is that it would easily fit in the dash hole for radio controls in 47-55.1 GM trucks.

Hi Bill,
That's right and great observation, by the way! There's positive and negative power for the board and positive and negative power for 2 speakers (R & L). Please see the attached image. You'll see a tiny cell on board which I'm assuming is what they've used for memory "keep alive." But at this point this board and I are still getting acquainted. More to follow. Yes, it would easily fit there or possibly elsewhere. I have made contact with another seller of similar radios over there but it is a slow process. The interesting thing is these folks seem to have almost no data about these things. They just sell them.

As for volume, there is more than enough from what I've seen. Plenty enough to drive you out of my work room and last night my wife asked "why are you playing that thing so loudly?" I had the volume on 3 and it could be heard in the back part of the house.

Would you connect this to the original truck speakers?

Well it is a stereo, so if you have twin speakers you could do that. My experience is using a stereo with only one speaker doesn't work well. You'll miss either the right or left channel and it is sort of like continually stepping off a curb with your left or right foot while you're taking a walk. The Dutch book I have been listening to has true stereo features (ie opening doors and street sounds coming out of one channel) and I was curious to see if I could hear them clearly (right/left, etc). So far it sounds very good (erg goed). Interestingly I haven't found a right/left balance splitter, though. And even more interesting while hunting for one I found an equalizer built into the thing with Pop, Jazz, Classical and maybe two more choices. Nice, since there isn't treble nor bass adjustment that I've yet found. But as you probably can appreciate lacking any information whatsoever about this thing, I'm on either a witch hunt or a treasure hunt (depending on your point of view).

As for the antenna (for the FM portion), I'm still giving that thought. Most vintage vehicles use what's known as a vertical antenna (which makes it sort of one side of a dipole antenna with the car's body providing the other side). You can also have a vertical dipole antenna, but I'm not certain that would work in this case. There are calculations for those I haven't used in over 40 years, though. Newer vehicles generally rely on a dipole set into the windshield for the FM portion. And interestingly the AD pickups which have the split windshield could theoretically use a dipole (each half set under the windshield weatherstripping and the central wire run behind the dividing bar. Or possibly just set into the trim pieces on each side. Don't know. I need to take some measurements and I need to re-study all of my antenna notes. As I mentioned this was meant to use an 8" long piece of insulated wire as the antenna (which isn't worth squat). So there is not a built in antenna plug on it, and for a typical vertical antenna that will be needed. But the good news is with a dipole made only from connected patch wires, local FM is coming in ok.

When I get a decent enough antenna, as amazing as it might seem, I believe this little thing might suffice for both FM and MP3...and even bluetooth telephone call answering if I can ever manage to figure that out. I know it is there. When you turn it on, the first thing you see is "HI" followed by bt...unless you've been listening to FM and then it tries to go to the station you've been tuned to (and may miss it by a point or two) or if you were listening to an MP3 file, it will resume that. And about tuning the radio, you can scan or you can enter the number. For 88.5 you enter 885. For 98.7, you'd enter 987 or for 102.5 you'd enter 1025. There appear to be some pre-sets in there. But like everything else it is a mystery. I can see them, but I have no idea how to set them. If this works (and more and more I'm thinking it will), I may be so shocked I fall backwards out of my chair. This is putting out quite a lot of decent sound for something this tiny.

For you 6 volt guys/gals, I've tried it on both 6 and 12 volts and it works fine either way...although it seems to lose just a hair of volume on 6v. Hardly enough to mention, though. The power supply I'm using outputs .8 Amp, so I think I originally overstated the amperage use.

Now for anyone who hasn't dozed off yet, you can see 2 images below of this. In the first image you'll see a display screen (3 numerals followed by a decimal point and another number), a right and left output level bar scale and at the bottom: USB, TF, FM and AUX. To the right of that an infrared led receiver, a 220 uF/16v capacitor and 4 switches. To the left what I thought was a cell is actually a microphone. And that changes my suspicion about what they've done for the "staying alive" feature. Mike makes sense if you'll be answering phone calls. Then a USB port, a TF/Micro SD card port, an aux port and 4 switches marked "next, prev, play and mode." The second image shows the back side and there are the 3 connectors, a 5v voltage regulator, a 26.000 khz crystal, a JHQB14F2P chip, a CS86552E chip and various surface mount resistors and capacitors.

Turns out a man in Croatia has done some legwork on a very similar circuit already:
http://www.crowave.com/blog/2022/01/19/projekt-osciloskop-clock-radio/ His has a clock and a power switch, but otherwise it seems much the same and his comments are interesting.

More to come in a while...

The way that board is designed it should be useable on a 6v positive ground truck like the earlier than 55.2 GMCs.

What! No AM radio? My local AM station broadcasts Astros games.

Yes, it should be. The 7805 regulator keeps anything up to 12v plus a bit to 5v.

Ah the Astros. Yep, that's a bummer. How about I include a crystal set for you, Bill? You could pull over in the shade, hang an antenna off a tree branch, ground the set to a pipe or something, put your headphones on and pretend you were a boy again. Just think of the fun. Not to overlook mosquitoes and onlookers.

Small update but good news. I have the USB slot working now...although I can't tell you why it started. I suspect a poor solder joint or possibly some problem with the slot itself. I did use a different USB stick and that might be the answer. The one I was using before was a larger capacity and this one is 1 GB. The micro sd card quit working, but that turned out to be a failed card. And a dipole antenna seems to work fine although I suspect a vertical antenna might be just as good or maybe better. Both will work. There are FM station pre-sets in there but I can not figure out how to set them for a particular station. Looks like there may be as many as 30 or more pre-sets, accessible via the remote unit...you enter 001 for P01 and if you scan pre-sets it will scan them all, playing a bit of whatever is there. And I figured out how to pair and activate the bluetooth cell phone function. Talked to my wife very clearly with it. Now I am trying to see if the phone will transmit (maybe MP3 or podcast-type files) back to the thing so it could play through your speakers. I've never done that before, so this part will be a learning process for me. I need a 10 year old around here. And maybe it is just me, but needing a cell phone to make your radio play a file seems incredibly backwards to me. Something a career politician would think made sense.

One thing about the bluetooth function and the telephone. It seems to work best when you can hit the pause button as soon as you hear your cell phone ring...but there isn't a pause button on the face plate of this one. I will be receiving different styles of these...some use this same circuitry (which I applaud for simplicity and curse for lack of available data) and some which use different chips and face plate buttons (another little mystery for us). Some of these have the pause button on the face plate, however I probably will not get these until early to mid August. You can use the little remote control that came with it, but that's less convenient in my mind (a distraction which I do not like while driving) and I noticed if I let the phone keep ringing the little thing will eventually answer it. I visualize a tiny transistor imbedded in one of the chips finally saying in a voice like Yosemite Sam "ok, doggone it. I'll answer the blasted call." Personally I would have built into the circuit an instant receive/interrupt/override feature for bluetooth phone calls, but apparently they didn't. Or at least I haven't figured it out yet.

Jon, great project! I'm imagining a flip down mount hidden under the dash. Flip it down to tune or whatever, then it's back up outta sight. When the time comes, Put me down for one please.

RonR

Thanks Ron,
I certainly will. I have finally heard from another supplier and have ordered different versions of this.

One of the experimental units arrived from China early. Faceplate looks exactly like the first one, however it doesn't have an amplifier built in to it, has an input jack (r, l and common) built in and seems to have been designed to connect to a separate amplifier. All functions work fine, however. Seems like it would be ok with headphones, but not running through speakers in a vehicle. 3 or possibly 4 more of these are coming...just can't predict when.

I said I'd get back about connecting to the FM/MP3/BT unit using a cellphone (using the BT function on the phone). I've since figured out how to do that and I can tell you the podcast I chose came in very clear...although it still seems wonky to me to have your cellphone "broadcast" music and stuff to your radio. I'm not at all convinced it is a step forward in the game of life but I do understand some folks think it is special so I'm keeping an open mind.

And I also discovered Mouser has a digital bluetooth 50w amplifier with volume control knob. DC input voltage between 5 and 27v (higher input v = higher output power). At 12v input, it outputs 20w and will drive either 4 or 8 ohm speakers, the maker says. It is designed to be connected to things like Raspberry Pi, cellphones and other main-controllers with bluetooth. So this is an interesting option...for the non-amplified version, that is. About $14 without shipping cost.

The amplified version needs only to be connected to an antenna or fed MP3 files from a USB stick. I got a couple of oval speakers out (one a Jensen and the other a Pioneer (both very good quality) and even on the lowest volume setting you get plenty of sound.

More to follow...

And by no means am I limiting the study to just these modules. As anyone who owns one knows the size and spacing of the radio is the big challenge in the AD trucks. Ideally what's needed is something that will fit completely in the blank-out space, but it isn't easy to find. Here is another idea which may be interesting. I found this on eBay and decided to take a chance. This is in ways similar to the other modules, however different in some notable ways: the large cyclopean eye in the middle houses a digital clock (evidently you must press a button to access it momentarily), MP3 via USB or Micro SD card, FM radio with pre-set buttons, and bluetooth...plus a few other features I haven't yet interpreted. It also has front and rear speaker ability.

In order to make this work in the AD, the unit would require some surgery (separating the operating board from the unit and making a new blank-out plate to house the unit and its buttons, etc). But the size is okay. That is to say it will fit in the space. The large eye in the middle displays station information, time, and number of track (from USB or Micro SD card file) and it adjusts volume. I just received this one and have not tried it yet. A little more futuristic or avant-garde in appearance, but not too bad in my opinion.

And today another unit arrived from China. It is smaller (1 inch tall by 4.25" wide) yet it also includes a very nice amplifier circuit, is also 5v regulated (so it will work on 6v or 12v) and the buttons are set up differently. It appears to have been assembled carefully and well. It has plenty of volume. And FM seems to pull in fine (I haven't tried BT or either memory card slot). Still amazing to me such a small unit can output so much sound. Like the other one it has equalizer, stereo, bluetooth (bluetooth antenna seems very nicely done on this board), etc. Aside from a couple of differences (different date, different board layout, different capacitor in one place), it is very similar.

I have learned the USB stick or the Micro SD card can not be set up with folders in which files are then stored on any of these I've tested so far. The units can't "see" folders, but they can see individual files and if those files are numbered (example 01 - Louie, Louie.mp3) they will be played sequentially. Folders cause the units to simply play dead. FAT32 is ok...I haven't tried others. Irritating baby steps. Wish somebody out there had compiled data on these, but I haven't found much that addresses all the abilities. Maybe that is up to me, eh? I've also discovered there are many of these units out there which basically look the same but are different. Some use a different circuit scheme.

In case you've been wondering, this project is still ongoing. What is needed first is a credible radio blank-out plate in which to mount the little radio/MP3/BlueTooth module. So in image 1 below you can see I've made my first silicone mold of the original blank-out plate. It takes time for these to cure and set and like anything the first attempt may not necessarily be my favorite. Still, this one turned out pretty okay I think. I'm going to do it again and this time I'm going to experiment with using plain old silicone caulk rather than the 2 part mixable stuff. In the second and third images you can see I've made a plate (I used clear epoxy and fiberglass mat and you'll see there was a piece of sock material, rug fuzz or something in that fiberglass cloth along with some long hairs...from whom I could only guess. I didn't care about them, however. Once lightly sanded and painted, they'll not be seen. Anyhow it seems to fit ok, so now I just need to duplicate (or re-design) the two fastening nuts before proceeding.

Jon, take a look at this stuff. I have a couple packages of it that I use when I either want to just make a couple of something or I am experimenting with the mold design/layout.

https://www.amazon.com/Amazing-Casting-Products-Extruders-2-5-Pound/dp/B00LZXVYF6

It hardens as it cools, so it is ready to cast in pretty quickly and it is reusable so it pays for itself in materials fast.

Thanks...I have seen that product and it is interesting. The part that pushed me away from it and toward pourable silicone were comments I found online about exothermic compounds (like 2 part epoxy) could be too warm for it and if so might cause the mold to deform as the epoxy went through its curing process.

Besides, there are not many options for replacing the radio delete plate, so I was hoping for a way to make a mold that might be useful many times. As you know the fiberglass or fiberglass/epoxy process takes a while to do correctly, but I've been told some of the delete plate reproductions out there aren't very good.

The plate could be made on a 3D printer. I made one for my ‘52, Because the original plate I bought from a fellow ‘bolter, did not fit the opening (it was too big). After looking closely, I found that my dash had been repaired due to an aftermarket radio installation and they didn’t get the dimensions quite right. The opening is slightly smaller than the original, thus the reason for making my own as I did not want to alter the original plate

If I had a dash with the original unaltered opening to test fit the plate, I could make one that would be repeatable. The one I made took three prints (and changes in Fusion 360) before I got it to fit correctly. The first picture is after it was sanded, painted and installed. The second is as it came out of the printer.

It may take me a few weeks but I will design and print one for you (at no cost) to try if your interested. I can send it to you to test fit in your dash, and alter it as required. PM me if your interested.

Hi Phil,
That would be helpful, thanks! As I mentioned I think there is a need for replacement plates. At least I see folks asking about them here from time to time. I wondered about a 3D printer, but I don't have one. In this case the bowtie emblem you added would interfere with the radio/etc. Can that be left off? Out of curiosity, what would be the apx cost of making these? Do you need measurements?

That was an added feature seeing that the plate was not original and made of plastic, I added the bowtie to make it unique. Once we have a plate that fits, you can add or subtract anything you want. That’s the easy part. The hard part is getting the contour and size correct. You can add a rectangular, round and pretty much any shape opening you like.

The spools of plastic are about twenty five dollars and not positive but I think I could get three or four out of it. The biggest part is they take about 12-16 hours to print. No big deal as I set it up and just let it go. You do have to keep an eye on it as sometimes things go wrong and if you just let it go you could end up with a bunch of plastic string glob’d together. I mounted a camera on mine so I can use my phone to view it.

You do have to sand, prime and paint them to match.

Once I get started, I’ll PM you on the progress.

Thanks, Phil.
Please tell me if you need measurements. My metal plate is sitting in a bed of silicone currently but I'll remove it tomorrow or the next day. The cost of the epoxy is a bit less. Takes very little time to mold but cures slowly with the formula the maker has chosen. The fiberglass resin/hardener will be also about the same cost, however it isn't as easy to get a smooth surface with it as it is with the epoxy. The CNC machine I have occasionally hiccups and heads off in the weeds, also. That's why I watch it run.

The only measurements I will need is the cutout for the radio. Judging by the posts, it seems to be uncertain as to which receiver you are going to use. In the meantime we need to get a blank that fits the dash. Once we have that, the hole is easy.

That is correct. I'm actually waiting for 2 other styles to arrive and the sizes are different. So far all of them have been interesting...interesting in that they have used the same basic approach but some have incorporated different electronic components to do the same job.

I will take measurements of the hole in the dash (has never been altered) and the blank-out plate I have (also hasn't been altered) and get those to you...as soon as I de-pot my plate from the silicone.

Thanks again!

I have an original blank off plate so I don’t need those measurements. I need to buy a repair piece to eventually fix my radio opening (cut from an original dash), so hopefully have something to test it out on.

Small but important update. I have received the female antenna plug connections and have more or less decided on one style of player. There are 2 questions remaining for the gentleman in China...are more of this style available? and how do you make the BT phone answering mode work? At this point I will admit the BT thing has been pretty much on/off and it may simply be that I don't understand it well enough. It receives BT transmissions, but then I haven't been completely able to make all samples answer the phone. Could be me. But the FM and MP3 (whether via USB stick or micro SD card) work just fine and I expect them to work well with a standard antenna, also.

The measurement for the opening is 20.5mm x 84.25mm

More as it is available.

Started to design the radio blank off plate and I’m waiting for an original dash panel from Mongo to fit it to. Once fit, I’ll be experimenting with different filaments that can withstand higher temperatures than what I am presently printing with (PLA).

OK, got it. How is it mounted?

I was thinking centered. (north/south and east/west) Here is an image of one I made out of fiberglass reinforced clear epoxy.

You may want to try ASA filament. It's what I've been using for all of my parts...UV stable, withstands high temps, and much easier to work with than ABS. Smaller parts like the size of a radio delete plate print great (almost just like PLA) but once you get into the larger parts the ASA tends to start warping if you don't have an enclosure.

I don’t have an enclosure and I was thinking PETG as that can withstand interior temps of about 175°. I’ll have to get a spool and give that a try. Thanks!

I didn't have any fiberglass resin that was still good, but fiberglass might be the best answer. I had to make this piece (with clear epoxy) thicker than usual because of the heat problem, but even thin fiberglass tolerates heat very well. Here in Dallas the internal temp of a vehicle can exceed 150 F easily and I've even seen it reach 170 F...and I should add the thermometer I had stopped at 175 F as the high limit, so it could have been hotter I suppose. The main problem I had was bubbles in the clear epoxy.

I did sort out the BT answering situation. You must switch to BT mode (easy) and then press the pause button momentarily. I also discovered the pre-set FM stations appear to be established with a scan of the area around you. Then using the remote that comes with it or the < and > buttons pressed momentarily will move through those pre-set numbers. Baby steps, but in time I will have a manual...of sorts.

Some more progress to report. I mentioned I had made a fiberglass reinforced copy of the blank-out plate before. I painted it to match the dash and fit one of the FM/MP3/USB/Bluetooth modules into it. The little screw cover plugs are just set in place as I do need to make an antenna plug, but you can see what this one looks like. As I said before, baby steps. The speakers I had ordered (from Mouser) got damaged in transit, so I'm awaiting replacement.

Jon:

I've been watching your progress and waiting for you to go into sales mode. Other than the lack of an AM radio mode (my baseball team broadcasts games on local AM) this looks like a good answer.

I'm assuming that the only sound output from the device is BlueTooth. Correct? When I G :(gle "Bluetooth car speakers" I get a bunch of rinky-dink plastic speakers that don't look to be much above low-end sound reproduction. I don't expect to have concert-quality sound in my rattly '52 pickup, but I'd like it to sound better than an early 60's transistor radio. Can you point me at decent BlueTooth speakers? If they would mount in the stock spot it would be better.

Keep up the good work.

Bill

Hi Bill,
Thanks for the message. This has been very illuminating for me. What we have here is a Chinese-designed circuit that includes an encoder for FM radio (sorry...no AM decoders are available in this style), an encoder for MP3 files (be they from a USB thumb drive memory stick) or a Micro SD card...or you can it seems use a stereo plug input from maybe an Ipod or something similar. And you can send BlueTooth signals to it (like a podcast)...it is happy to receive those. And if your cell phone is mated with it (assuming your cell phone has BlueTooth ability), then if you receive a phone call you can push the Mode button until BT appears and press the Pause button quickly and answer that phone call and talk hands-free. The board has a BT antenna built in and the maker claims it has a range of something like 20 feet. I'm still learning about how to operate these and will write some instructions at a point. I have the boards sent in from China but there are no instructions and communication isn't always the best. I am comfortable with several languages, but in Mandarin I only know about 15 words and most of those are things like "hello, thank you, chicken, not spicy, etc"...restaurant Chinese. Bottom line is you can listen to FM radio, music or speech MP3 files, podcasts, phone calls...a pretty nice range of options.

The sound out of this is pretty impressive in my opinion. I have so far only used it in the house but it seems to have plenty of volume, the sound is clear and while it won't be concert-quality, it will be better than an early 60s transistor. It reminds me of listening to audio through a computer or maybe a tv. As for the speakers, we'll need 2 (this is an amplified stereo board). There does not seem to be a balance setting...seems like they just split right and left 50/50. I've chosen some German speakers from Mouser. They're $7.62 each plus cost of postage. I just received them this morning (original shipment was damaged so they sent replacements). I'll see how they do. You can see them attached. They're 4" diameter with decent sized magnets. You can spend a lot for speakers but unless you're building a special cabinet designed for them, I'm not certain that's money well spent. In the AD, they just mount behind the speaker grille in an open fashion, so I think a really expensive set of speakers might be overkill.

Please stay tuned. More will follow as time passes. So far, making the blank-out plate has been the most challenging, but I did get some new fiberglass resin, so I'll try that soon.

Jon, don’t give up on me yet! LOL I bought a replacement dash panel, so I can eventually fix my screwed up dash. It also will give me a stock original radio opening to fit the 3d printed radio blank to. I’m getting one from Mongo and he switched labels on two orders. I ended up getting someone’s else’s part and they got mine. All straightened out, but I have to wait until he gets both parts back and he ships it out again. Should be here within a week. I’m going to use PETG to print the part which is good to 180°. I also believe it can be tempered in a oven to raise the temperature tolerance to over 200°. If that fails, I will experiment with other filaments that can withstand higher temps.

The beauty of a 3d printed part is, once you print a part that fits, it’s repeatable and easy to reproduce.

So the speakers are direct wired to the unit?

If so, I already have a set of (4 ohm?) speakers mounted in the stock position in the dash that I can use. The balance isn't important to me as the speakers are about 6 inches apart center to center.

I did some speaker cabinet work back in the early 70s. Did the tuning myself with the help of a book that should be around here somewhere that had crossover and port tuning sections. Can't remember the name of the book, but it was paperback, had a blue cover, was about an inch thick and had examples from Lansing and Klipsch.

I haven't given up at all, Phil. I've just been working at this as I mentioned I would. And it has been a while since I've done much fiberglass work.
Bill, yes...there is a + and - connection for right speaker and left speaker plus a + and - connection for either 6 or 12 volts of power...or more probably up to 24 or maybe 27 volts. There is a voltage regulator chip on the board which reduces incoming voltage to 5v. So, to answer your question the speakers (and 4 ohm should be ok) will have wires and plugs to connect them. I may have seen that book, actually. There was an engineer working at TI who lived above me in the apartment building and he loaned me an interesting book about speaker design. I'm pretty certain it was blue also. This was a long time ago, however.

Book

That might have been it. Would have been early 70s.

My replacement dash (radio section) has arrived, (thanks to Mongo) so I should have a 3d printed radio blank off plate soon. I’m going to perfect it in PLA first then, reprint one in PETG, as it’s a new filament for me. Making progress!