Maker Pro

Portable stereo/MP3 player for when I work outside

I'm revisiting a project I made a couple of years ago to improve the housing (& probably make it sound a bit better too).

Project Log

The current project is mainly moving this project to a new case but first a bit of background:

For many years I have recorded streaming radio programs to listen to in the shop. I retired in 2016 and started catching up on household maintenance and renovation projects that I didn't have time or energy for when I worked full time and in 2017 I added a vegetable garden (which has expanded since then) so when the weather is nice I spend quite a bit of time outside. I still wanted to listen to my recorded shows while working so I lugged a small laptop around with me for the first few years but by 2019 I decided a small stereo that I could play the (MP3) shows on would be better so I started shopping.
I was intrigued by the panel mount modules that are on eBay and other sites so I ordered a "5V MP3 Player Decoder Board LCD Screen Amplifier 3W*2 Music Player USB FM Radio" with a vague idea about bolting a pair of old computer speakers together, somehow attaching it and using USB power banks to power it.

By the time it arrived I had at least had more time to think about what to do with it. It would be ideal for replacing the electronics in an old portable radio but unfortunately the closest thing I had was an old clock radio cassette recorder combination and it was too big. But it did have 2 little speakers that matched. The first thing to do was test it so I pulled the front panel off of the donor radio, connected the module its speakers and hooked it up to one of the power banks I bought to power it.

My biggest concerns were whether it would play long MP3s (the programs are 1-4 hours long) and turn it off in the middle of a program and start at the same point later. I determined that it had no problem with long MP3s and as long as I pause it before turning it off (or disconnecting the power) it will remember where it was so this is perfect for what I need.

Now I need some kind of case to hold it all. I couldn't find anything suitable for sale and was starting to think about making something when I remembered a pile of plastic cases from tools &c on a shelf in the garage shop. After a couple of false starts I settled on one, added strips of masking tape to lay it out on and and started making holes (shown after I started removing the tape)

These speakers don't have holes for mounting screws and the clips that held them in weren't suitable for this so I made clips out of some electrical box parts. They would have been fine if the front of the case was stronger but when I tried tightening the screws it became obvious that I'd need to reinforce it and the knock outs from where wires enter metal electrical boxes were my choice because they are longer than they are wide and the long ends let them reached the edges of the speakers.

The electronic part wasn't complicated, just solder the wires onto the speakers & USB plug and a wire for the antenna. The 4 round black parts were made for attaching speaker grille cloth frames to cabinets a lifetime ago but they were perfect for keeping the power bank in place.

The speakers needed some protection so I glued on some grilles that were made for tweeters 40 years ago (can you tell I worked in the speaker industry once?). I believe the handle I chose came from a piece of electronic test gear I scrapped decades ago but it looks like it was made for it. I also wanted a way to attach the remote when it isn't in use so I attached a couple of small magnets to the back of it with black duct tape so it can stick to the grille. The REK logo (based on my initials) was designed by my late friend Bill for some speakers I put together a few years ago.

It didn't take me long to decide that I didn't like having the USB flash drives stick out so far so I bought a few of these. They are actually TF (micro SD) card readers that use the card as the tongue of the USB plug. Very neat.

I got a lot of use out of it during the last 2 years but the case was never truly adequate. Besides not being very strong it is also very thin so it falls over easily and the front (which was never as strong as I would have liked) became badly cracked when a strong breeze knocked it over last fall so it has been held closed with elastic bands while I searched for something better to house it in, which brings us to the current project: preparing a new case and installing the player &c in that.

Mar 17 update:
Over the last couple of months I've spent a lot of time wandering around stores and searching online for a better box to mount it in without finding anything suitable. One day last week I was at the gardening bench (the basement shop has benches on all 4 walls) transplanting tomato seedlings from a tray of starting mix into little pots of dirt when I happened to look up at the stuff on the shelf above it and saw something that made me pause and get out my tape measure. The size was good and it looked strong enough so the next time I went shopping I bought a new one to turn into a case

Yes, that's right. It is a plastic mud pan for drywalling. Right after I took the pic I gently pulled out the metal strip and removed the plastic ridge on the opposite side with a sharp chisel. It would need a front panel so I dug out a sheet of 1/8" thick plastic that's been laying around waiting to be used forever
The ryoba (Japanese pull saw with rip teeth on one edge and crosscut on the other) is perfect for cutting things like this

The plastic is textured on one side and smooth on the other so I covered the smooth side with masking tape and started laying it out:
- The first step was to draw a line around the edge about 2mm wider than the lip on the tray.
- I marked the centre of the panel and located the module centred and as high as possible (the line highlighted in yellow is the opening).
- The front of the new case will be shorter top to bottom but longer end to end so I have room to use the tweeter trim rings I wanted to use last time but couldn't (they are mostly cosmetic but will add a bit of strength to the panel) so I figured out where they would go, traced around them, marked the screw holes and found the centres from those.
- The larger rectangle highlighted in yellow is the opening for the recess that the power bank will sit in

A few days later all the holes were drilled and cut (it doesn't look like a lot of work but it is time consuming):
- I used the razor saw for the rectangular holes (these were bigger than on the mA meter so it was a bit easier but I still need to get a smaller saw for stuff like this).
- The bench top (3/8" chuck) drill press in the basement shop is perfect for drilling all these little holes but I used the big drill press in the garage shop with a fly cutter for the 59mm speaker holes (those could have been a bit bigger but they are the same size before so they'll be OK).
- Before I knew what size of holes to drill for attaching the panel to the box I needed to find 22 suitable bolts & nuts so I spent most of an hour digging through a can of little bolts salvaged from computers (inherited from my son) and came up with 23 M8 x 8mm bolts. I had a bag of M3 nuts left from another project (I try to order extra if I think I'll use the same part again; I'll have to order more soon).

When I was putting this together I bought two 5300mA power banks so one could be charging while the other was in use. Because the module doesn't remember where it was if the power is shut off without pausing the player I prefer to change to the fresh one when the charge indicator is down to one LED still lit so the power bank needs to be where I can see the LEDs.
I had originally hoped to build a recess for the power bank to sit in by solvent welding pieces of the same plastic sheet as the front panel; Unfortunately I don't know what this plastic is and none of the solvents I have would touch it (super glue wouldn't bond it either so I suspect it may be polyethylene). So I had to come up with another way. I had some pieces of 1/2" square walnut in the shop that would work but the recess wouldn't quite be deep enough so I cut strips of the plastic to shim them.
Here are the parts for the recess ready for assembly (I treated the wood with boiled linseed oil). I didn't have anything suitable for holding it together so I bought a pack of twelve #6-32 x 1" flat head bolts & nuts (exactly the number I need).

The winter sidecar outfit hasn't had any maintenance for a while so I need to spend some time in the garage with it this afternoon while the weather is nice but I'll get back to this as soon as I can.

Update March 19 (final)
If I was buying the sheet for the front panel I wouldn't have chosen that colour but I've had this stuff for a long time and want to use it up. And if this was going to spend most of its life on a shelf this is when I would have painted the front panel and probably the mud tray but it is going to be carried around where I'm working and I'd rather have these colours than something nicer that ended up with a lot of chips & scratches.
But I did do a bit of painting. I like the way another pair of speakers I have look with silver cones behind perforated grilles so I gave these ones a quick spray of silver paint (it won't hurt them - if anything the paint stiffens the cones a bit). The speaker holes were smaller than the openings in the trim rings and I didn't like rings of yellow showing around the speakers so I masked the front of the panel and sprayed an area around each speaker hole with gloss black.

In between all of that I found some feet that were tall enough to keep the lip off the ground and drilled holes in the bottom for them and moved the antenna and the handle to the new box. I knew the trim rings were just too deep for the magnets on the remote to stick to the grilles so I added a steel mending plate to the end for the remote to hang on.

The 4 holes for each trim ring are on a smaller radius than the 3 washers I used before so I had to re-bend the 6 clips I had and make 2 more. That doesn't sound like much but it took a couple of hours to get them right and get the speakers bolted on with the grilles centred under the rings (no sloppy glue this time).

And then I assembled the recess so I could figure out a strap to hold the power bank in. I found a suitable piece of rubber and cut it to fit fairly easily but it took me quite a while to figure out how I was going to attach it and find suitable screws &c. Remember that pack of twelve #6 screws that were exactly the number I needed? They were exactly the right length too so I had to find a longer one for where the snap fastener attaches. There wasn't a bolt where the other end of the strap would be so I found a #8 round head long enough and drilled one more hole.
After I had all of that done up I realized that the power bank wouldn't come out of the recess as easily as I thought so I had to find a piece of ribbon to pull it out with and undo half of the bolts to trap it between the front panel and the piece of wood.
All of the fiddly stuff like that (+ finding screws, picking the old glue off of the grilles &c) is what takes most of the time on a project like this.

Eventually it was ready to put together.
BTW: I never really liked the module's original cheap slide switch for the power so instead of cleaning it when it started acting up after it was rained on last summer I filled its hole replaced it with a push on/push off button in the front panel but this time I decided to change to a mini toggle switch instead.

After that all that was left was the 22 M3x8 screws around the edge of the front panel and it was finished.
Bottom & back

The remote hanging on the end

Front view. I'm already getting used to that yellow/caramel colour. It is much more sturdy and won't fall over as easily. It's not exactly "Hi-=Fi" and there was no way to do an actual A/B comparison to verify but I'm pretty sure it sounds better too.

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Sidecar Bob
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