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Discussion Starter · #1 ·
I've been emailing the owner of SimpleCircuitBoards today about a possible modification to one of his existing products that would allow the MP3 player to be used. It would be controlled in the same fashion as the timer board I designed earlier this year. I know several people have purchased the players for sound looping. If he can make this mod easily, we may have a source for off-the-shelf boards than can control the player. It may be premature to mention this at this point since he's still thinking it through, but is there any interest in having this capability?
 

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Discussion Starter · #3 ·
I just got an email from the owner and he's definitely interested in building this board. He'll be working up a prototype in the next few days and sending it to me for testing.
 

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Discussion Starter · #5 ·
I heard from the owner of SimpleCircuitBoards today, and he's got a list of enhancements he wants to try. Stuff like expanding the range of voltage that can be used to power the board, an LCD display to allow the user to program the "on" time in minutes and seconds, loop function, delay-before-play etc.
 

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Discussion Starter · #7 ·
Alright! I got the prototype board today and it works beautifully. Programming is simple, just load the MP3 file in the player, plug it into the board, set the time, and go. A 2-line LCD panel displays the times and mode that its in. You just program the startup time, which can double as a delay before play, since the player won't start until the On button is released by the timer. Add a couple of secs of silence to the end of the file, enter the Play time and you're ready to go. It also has a looping option and you can set the time interval for that, as well. Couldn't be easier. I'll get a pic up tomorrow. I love this thing! Really makes the MP3 player easy to use.
 

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Discussion Starter · #16 ·
I've been using ISD boards for a while now, and the biggest issue I have is sound quality. The 60 sec chip plays back at just 8kHz, about what a telephone sounds like. They're also very sensitive to recording input levels and the sound can become distorted easily. The 120 sec chip sounds very muddy, even compared to the 60 sec chip. Another advantage is you have stereo with the MP3 player, making it easy to set up a conversation between talking props.
 

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Discussion Starter · #17 ·
Looks Great!!! I just picked up 5 more of these players. Ouch!!! on the price...He will have to do better than that. I was expecting maybe $39 with the player. Does his board work for any player or just the $5 cheap one?
I think he's designed around the $5 unit. Playback triggering is probably different from one player to another, and this board is designed to "press" the Play button for 1-2 secs to initiate playback. See the pic I posted earlier to see how the MP3 module connects to the board.
 

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Discussion Starter · #20 ·
I have been using an ISD board with my talking Reaper. Last year the TOTs complained that they couldn't understand what he was saying. I used the MP3 player with the same audio file last and it made a serious difference, both in sound quality and performance of the servo driver board. A trick I learned - put the spoken track on one channel and use the other to drive the servo. I put a steady 500kHz tone on the unheard channel and sliced it up to match the vocal track. You can manipulate the amplitude, length and decay of the tone sections to get super-clean performance from the servo. Very helpful for tracks that use reverb, echo and other effects that can confuse servos.
 

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Discussion Starter · #22 ·
I emailed Jeff with the pricing concerns and he has an idea. Break the board into two functional parts - one would have the LCD and the progamming components, the other would have the MP3 module and playback/triggering components. Together they would cost about as much as the current board, but the player portion would be less expensive (his estimate). This may allow buyers to get more than one "player" board and program them from one programming board. He still needs to do some design and prototyping work, but this may be an option. What you folks think?
 

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Discussion Starter · #25 ·
I wonder if the board could be made using other devices to display/indicate the time values that were programmed? I agree that the LCD is a costly part of the board. I'll ask Jeff if there are other ways to indicate the programmed values to the user.
Regarding the use of a Prop-1, the issues there are that you must use a computer, learn PBasic (not difficult, but since I teach VB/VBA courses I know what to expect), and if changing the On time is needed, you have to re-code the sub. This board is able to be a stand-alone device if attached to a 9 volt battery.
Please keep in mind that products like this (short-run board fab, manual assembly, design/engineering time) can be more costly than a scaled-up commercial product.
I saw that MPJA is getting low on the players. I found this place:
http://www.watchcloseouts.net/ecommerce/Scripts/prodList~idCategory~56.htm
They have ~550 of them in stock. You have to create an account to view the price - it's $9.85 each.
 

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Discussion Starter · #26 · (Edited)
Great idea! How did you generate the 500kHz tone?
I used GoldWave to set up the file. Put the vocal track in one side of a stereo file. Use the Tone Generator function to place a 500kHz tone in the other channel. Select that channel and adjust the volume down to something reasonable or it will drive the servo to max all the time. You'll see the "spikes" in the spoken track. Select the parts of the tone track that do not correspond to the highs in the spoken track, and set the volume to "0". When you're done you'll have a chopped-up tone track that mirrors the vocal. Test the file to see if you've got the timing right, and make adjustments to the length of the tone sections to get the correct jaw movement, a little movement for short, quickly spoken words and more for louder ones. You can also use the Fade function to taper the volume of the tone section. This works really well for making a laugh to look right - usually the servo just drives to max and stays there. Also helps with servo bounce when echo effects are used. When you're done, send the spoken track to the speakers and the tone track to the servo board. I have a short MP3 sample file that I'll send you so you can see how the tones are arranged. I built it in GoldWave but you should be able to use Audacity or other editors to open it.
 

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Discussion Starter · #28 ·
Programming a Prop-1 wouldn't be an issue for me at all, but may be a stumbling block for others. Agreed about the 9 volt battery - I'll check it out.

Did you see my second post about the using the Tone Generator in GoldWave? The latest version makes it real easy to do, but earlier versions require you to enter a few values in the Function Generator dbox. I don't use Audacity, so I don't know if there is a corresponding feature for creating specific tones.
 

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Discussion Starter · #32 ·
OK, here's the latest from Jeff at SimpleCircuits. He split the board into two functional parts - a Programmer and a Player. They connect with a ribbon cable. The Player holds the MP3 module. Once programmed, the Player is disconnected and used in your prop. The Player board has the power input and dry-contact trigger input. The Programmer board draws its power through the ribbon cable when they're connected. Of course, multiple Player boards can be used with one Programmer. If you already own the MP3 module(s), Jeff will sell the wired connector that allows you to plug it into the Player board. You still have to solder the wires to the MP3 module, but that's quite easy to do.

The prices are:
Programmer board - $41.00
Player board w/o MP3 module - $27.50
Player board with wired MP3 module - $40.00

Sorry, I didn't get the price of the separate wired connector from him. He'll have this board up on his web site soon.
www.simplecircuitboards.com
 
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