Cheapo MP3 player update

bourno said:

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

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I hear ya. I'm not giving up on the controller chip, though. If I can find the right info, I'll re-design.

Another oops! I re-checked the timing calc's and found that the 1 MOhm resistor should be a 100K. This is part E on the circuit drawing. Apologies for the mix-up. The minimum playing time will be ~24 secs, max time ~4.4 minutes.

A quick update:
The circuit design is verified. I'm changing one of the relays (the DPDT) to a 6VDC to handle any voltage dips that a low battery might deliver. The current 12VDC relay only works reliably with a 12VDC power supply, and I want this thing to be completely stand-alone. I have lots of pix for the how-to and am compling it a little each day. Cropping pics sure can take a lot of time. Thanks for your patience, and for the valuable input and critiques of this project. I'll get the parts list up after I install the 6VDC relay in the test board and confirm functionality.

Thanks for all your effort with this Otaku, these things seem to always take a few revisions before they are right.

I tested the 6VDC DPDT relay today and everything works on a 9 volt battery. Many thanks to gmacted for pointing out the correct direction for the diodes. I'll be out of town for a few days, but I will get a complete parts list up next week. A note of caution: do not get the polarity reversed. I did that today and immediately blew a hole in the 556 chip.
For some reason I can't upload an attachment here. I'll try to post the circuit layout to Halloween Gallery.

Nope, still having problems with Halloween Gallery uploads, too. If anyone wants to see the latest revision, drop me a PM and I'll email the pic.

I've had some requests for the final circuit layout for this project. I posted the pic on Halloween Gallery:
http://halloweengallery.com/displayimage.php?pos=-3678
Let me know if you have questions. Again, mucho thanks to gmacted for the help on the fine-tuning of this circuit!

Otaku said:

I've had some requests for the final circuit layout for this project. I posted the pic on Halloween Gallery:
http://halloweengallery.com/displayimage.php?pos=-3678
Let me know if you have questions. Again, mucho thanks to gmacted for the help on the fine-tuning of this circuit!

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You deserve all the credit here Otaku for the great idea! I'm just glad I could help a fellow Hauntforum member.

Here's the parts list for the project. Some items, like resistors and diodes, have minimum quantities that you have to buy, but they're the really cheap parts. I didn't include the cost of wire since we all have some of that lying about, nor the cost of the USB-A sockets.
The how-to is coming along, but my schedule has been pretty crazy lately so it's taking longer than expected. Thanks for your patience.
Here's the link to the parts list:
http://halloweengallery.com/displayimage.php?pos=-3679

As some of you have probably guessed, some of the parts are optional. You can use any enclosure or box you want to, and wire nuts can be substituted for the 1/8" jacks and plugs for connection to the controller and MP3 player trigger wires. The cost seemed pretty high to me after I totaled it up, so some of these subs will reduce the price.

I posted some pix of the completed board today. I'm still learning Adobe Elements 5.0 so it's taking a lot longer for me to be able to edit pix and insert text boxes etc.
http://halloweengallery.com/displayimage.php?pos=-3680
http://halloweengallery.com/displayimage.php?pos=-3683
http://halloweengallery.com/displayimage.php?pos=-3682
http://halloweengallery.com/displayimage.php?pos=-3681

More to come...

I have a PDF of the instructions for wiring the IC into the board. I'm still working on the pix for attaching the pot, relays etc, but this part of the assembly is the most difficult. It's too large (737KB) to upload to Halloween Gallery, so if anyone would like to get a copy or post it on a web site, PM me and I'll send it along! Thanks again for your patience.

Otaku,

I wanted to thank you for posting the cheapo mp3 player link. I purchased 2 for my talking skulls and I'm thrilled with them!
They work great!!!

I have posted Otaku's PDF on my web site along with the the parts list and schematic drawing.

Otaku's MP3 hack
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I just noticed that the 6VDC DPDT relay (RLY-468) at All Electrtonics has been sold out. You can substitute the RLY-642 relay for this component on the timer board.

I have uploaded Part 2 of Otaku's circuit onto the the link from earlier.

bourno said:

I have posted Otaku's PDF on my web site along with the the parts list and schematic drawing.

Otaku's MP3 hack
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A quick note - I built a third timer board this week and found that the 1.0 uF cap/1.5 Mohm resistor combination did not allow enough time to trigger the player. I added a 100K resistor to the 1.5 MOhm in series and that fixed the problem. I'll include a pic in the last part of the how-to that shows how to cut in the 100K resistor. This was likely caused by variance in the cap - tantalum caps have ~5% tolerance.

Just curious - has anyone tried building this timer yet? If so, would you let me get your feedback as to the accuracy of the layout drawing. Also, does the how-to cover everything OK, at least up to this point? Thanks!

Otaku said:

Just curious - has anyone tried building this timer yet? If so, would you let me get your feedback as to the accuracy of the layout drawing. Also, does the how-to cover everything OK, at least up to this point? Thanks!

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I plan on building one or two of these. Everything looks good to me, but I may not be the best person to ask because I know how the circuit works.

Yeah, Greg, I was more interested in the feedback from folks that don't work with this stuff regularly. I tried to plug in as much detail as needed without being too overbearing - hopefully I didn't miss anything critical.

I've completed one of the MP3 timer systems, and will (hopefully) be able to enter it in the $20 Prop Contest. Yeah, I know it's not really a prop, but these devices will sure improve my sound effect capabilities. I should have Part 3 of the how-to finished by next week. Thanks, everyone, for your patience.

Later - Just heard back from Z-F, he says no problem entering it for the Prop Contest! Thanks, Z-F!

I finished building out one of these last night, and I've been playing with it this morning. Setting the "on time" period is quick and easy - it takes me 2-3 tries. I'm adding a 5 sec. silence period to the ends of the test files so I don't have to be exact with the setting. The timing appears to be very stable and repeatable.
Something I've noticed with these players: I tried using one with my talking Reaper, and found that the low output voltage level of the player doesn't work very well with the servo driver board I have. It's an older AutoTalk board from BPE, and I think they designed around the 2.5 volt output of the ISD chips. I'll either have to add a small pre-amp or change to a different servo board.
Has anyone used these players with a Scary Terry board? Carl at Cowlacious said the S-T boards can handle fairly low input voltages, but wasn't sure about the behavior with these players.