diy kid stereo

This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
hello all - not sure where to post, so here it is...

Hopefully a bit of a relief from the hardcore transistor talk:)

problem: my daughter, who is 2, loves music. we purchased a crappy kids overpriced cd player for her at one of the big box stores and she loves pushing all the buttons and she sometimes will get the cd in the right spot. But she has also ruined a couple of cd's along the way (which i don't care because we've backed them up anyways) and the cd box just doesn't fit in to our digital lifestyle..

solution: I want to make a simple digital music player for her (mp3's etc). I envision that this player would have a top "console" with a total of 7 oversize kid friendly buttons. 5 "playlist buttons" and a stop button and a play/pause.

Workflow: the "plan" is to create 5 folders containing various mp3's on my laptop - each folder would become the playlist corresponding to the 5 playlist buttons on the console. their would be only one port on the stereo, and that is a usb port. I plug my laptop into the stereo and the laptop mp3 files (5 folders) are copied into the stereo.

hardware: I would love anyone's input here. I could either find an old pc to use as the box, and build the console and then somehow integrate the console to the box, but I'd rather just get a hard drive, some basic motherboard, a linux install and a way to integrate the console. some basic engineering advice here would be appreciated.

The disclosure: ok, so I sometimes take on bigger projects than I can handle. is their a simpler approach?
that sound pretty complicated - you have to build a digital source, amplifier and speaker system. IMHO, that a big job.

There is this for a start:

If you insist on going the whole hog, look around for diy ipod docks, there may be a design or two on this site, but probably more on You might be able to tear apart an ipod knockoff and make your own enclosure with big buttons...
I agree - this is a fairly large job - but not really all that difficult, provided you have a bit of shell scripting experience and the fabrication skills you need to put the bits together.

Grab a nanoITX or miniITX like the VIA EPIA (or larger depending on how much room you have...) motherboard, CPU & RAM, a 4GB USB drive, and a small power supply like the picoPSU and you've got the hardware you need. Probably can be done for about $125 for the full deal here if you use eBay. This auction seems a good start.

For the buttons, it's pretty easy to cannibalize a PS/2 keyboard and wire your pushbuttons to short some of the key positions (google for DIY arcade machines and you'll find details); you can then write some fairly simple Perl or whatever to control a player, or just customize the keyboard shortcuts for an existing app that you start at boot time. If you wanted to get fancy you could use the parallel port to drive some LEDs to show which one is currently playing or something like that too.

The USB connection you want is a bit trickier, since most motherboards can't act as a USB 'device', only as a 'host', you won't be able to do this easily. Ethernet or firewire would be simpler to do. Either way, you should be able to use hotplug to detect the device connection and fire off a shell script to sync the shared directories.

Add a little 2-15W class D amp module (e.g. the cheap ones from SureElectronics on eBay) and some speakers and you're set.

Casing it nicely and childproofly will be the difficult part.
Why not just get one of those cheap 512MB mp3 players and break out the buttons on it. If you can get one of those old Fisher Price wind-up "boombox" music players and re-wire it with some NiMH powered Class D laptop speakers, you have what you want. If you break out the USB port power and hook up the batteries also, you can dump music on it and recharge at the same time. If putting folders on the player is too difficult, just "combine" all the mp3's into 5 big files and then burn. That way, skip just starts the next "folder."

Purplepeople's approach makes a lot of sense. There are a number of MP3 players that accept SD cards; that would make it easy to change the music. You could go with the whole embedded PC, but an MP3 player with 6 buttons would probably be "good enough", and more reliable.
the advice

thanks everyone for the advice! I'll probably try the easy way first with a modified mp3 player. I'll report back on the results.

But this really begs the future diy project of a kids media box that could be used for video as well. much bigger project and more cost but considering the "junk" that most parents buy their kids, well worth it..


Add a little 2-15W class D amp module (e.g. the cheap ones from SureElectronics on eBay) and some speakers and you're set.

The 2W module can work on 4.5 volts and it can be given a very tiny input filter cap (0.01uf to 0.02uf) so that it can actually make 1W clean. This could match up with 3" speakers. The batteries last very well. The kit contains 2 mono amps. Shipping time is about a month. If they're later than that, sometimes they gift an extra module.

With three, you can place a 50k resistor in parallel between the source and input filter cap (that you provide) for left and again for right.
The third can be given two of 15k loads and a pair of half-size input filter caps. This is the stereo input for the center channel speaker. ;) The layout "steals" center information away from left and right, thus broadening the soundfield.
This example, the loads depend on how much gain you'd like. The proprtion controls the surround effect. The input filter caps are between the loads and the amp. They control the bass output whereby less bass is less clipping.

The 15W module is a stereo tripath, capable of running any size speaker; however, the batteries will not last. Since voltage max is 13.8 volts, if given a regulated power, is capable of recharging 8 NIMH "D" cells. The factory input filter caps are 2.2uf, which is fine for 4" to 6" speakers and shouldn't easily exhaust the limited 680uf tank capacity--which was set at that size to preserve battery power. Shipping time for this model often exceeds two months.
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.