Cheapo MP3 player update

Thanks, gmacted. I fixed the error in this drawing. Please note the solder locations on the MP3 module's play button - I found these to work for starting the player, but they're very small surface-mount pads. Use a small solder tip and 30 gauge wire. I plan to use a 2-pin Molex connector to attach these wires to the circuit board. You need to be able to disconnect it to upload files.

Oooops! The software dropped a line where it didn't belong - here's the corrected version. Note: the MP3 player is shown with the case opened.

Otaku said:

Thanks, gmacted. I fixed the error in this drawing. Please note the solder locations on the MP3 module's play button - I found these to work for starting the player, but they're very small surface-mount pads. Use a small solder tip and 30 gauge wire. I plan to use a 2-pin Molex connector to attach these wires to the circuit board. You need to be able to disconnect it to upload files.

Click to expand...

Very nice indeed!

I've almost finished the parts list for the circuit. Almost everything you need is at All Electronics. The hardest part to get is the USB-A female connector. Jameco has them (p/n 161023, 0.79 ea.), but you get stuck for shipping one part. What I did was to request free samples from Keystone Electronics.
http://www.keyelco.com/products/specs/spec141.asp
Click on the sample link and make up some info about your "company" and how many you plan to buy each year (at least 1000), and they'll send them to you for free. I got 10 of them, but they did email me saying that this was more than they usually send for sampling. Try for 4-5 and you'll be OK.
I want to post a decent how-to for the assembly of the board, so it's going to take a little while. I want to get lots of pics as I go along.

Circuit map

I made a layout drawing of the circuit to make it easier to see where everything goes. It's based on a PC-3 board available from All Electronics. All questions and feedback are welcome!

I haven't gotten mine yet, but why do you need a female USB connector? Is there not an easy way to just break the power of the battery in the battery part of the player by adding an insulator there and use the relay to remake the connection?

Maybe it will make sense when I get mine from MPJA

Actually, I did think about doing it that way. You could tap into the battery terminals in the case and wire Relay A to control the power, it just needs another Molex or similar connector. I just liked the ease of plugging the MP3 module into the board.

I'm expecting the parts for this hack to arrive next week, at which time I'll start the how-to. There's going to be lots of pictures and text, and trying to post these will run me out of attachment space real quick. Is anyone interested in hosting the how-to on their web site?

Not a problem for me to help you out on that. I am sure more will volunteer as well

Thanks, bourno! Let me know what formats you'd need for the pix and text instructions and how to get them to you - the parts are on the way.

I can help too if you need it.

Do we have a "Final" Diagram / Schematic this thing has changed a few times which is expected. I started to build it and stopped when it changed a whole lot. So I am trying to get back in sync.

Yes, the final circuit layout is on my post dated 1/19/07. I don't know how to link to a thread or post.

For those who will be building this circuit, go to R/S and get a spool of bus wire:
http://www.radioshack.com/product/i...&cp=2032058.2032227.2032239&parentPage=family
It will make the bus bar layouts way easier, as you won't need to strip wire.

I'm putting the first board together and taking pix as I go. After I finish the first one and test it, I'll post a parts list. More to come...

jpg pics would be best for me. I will just copy and paste in the text from either the e-mail itself or if you wanted to microsoft word, that would be fine too.

Send them to bourno (at) teambac.com

I will just add a "Otaku MP3 player hack" to my project page list. I just got back from a work trip and gonna have to make some time to see what addition hacks could be done to the player.

I have thrown together a small how-to for using it with a Prop-1 or similar type controller board. I haven't soldered anything up yet, but did the testing by manually jumping the connections at this time.

http://www.teambac.com/web_hall/MP3_player_hack.html

Looks good, bourno! Is the Prop-1 able to detect the end of the MP3 file to prevent replays? That's the biggest hurdle I ran into - nobody seems to be able to find any info on the player's controller chip. I did find a datasheet on the MP3 decoding chip, but none of the output pins had anything useful for detecting end-of-file.

Otaku said:

Looks good, bourno! Is the Prop-1 able to detect the end of the MP3 file to prevent replays? That's the biggest hurdle I ran into - nobody seems to be able to find any info on the player's controller chip. I did find a datasheet on the MP3 decoding chip, but none of the output pins had anything useful for detecting end-of-file.

Click to expand...

But if you know the length of the sound file being used, couldn't you program a pause into the prop-1 and then have the prop-1 stop the playback before a replay occurs? Of course, you'd need to change this pause time based on the length of your sound files, which means changing it any time you use a new sound file.

It would be like yours Otaku for needing to time it out for pulsing the play/stop button again as Zombie mentioned.

It is just too bad there isn't any easy way to make it behave like we want instead of needing a controller that could be more expensive than the MP3 player But, if a person was already using a prop-1 or similar on the prop already, it would be a wash then

The pause between replays is ~ 0.5 sec, according to my 'scope. Of course, if one adds a few secs of silence at the end of the file, it gets easier to hit that target. True, you would have to recode the pause or relay-off for each change in the file length. The 556 circuit allows setting time periods on the fly.