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Discussion Starter #1
Hi all,
I worked out the timer circuit for turning the player on remotely. It can be activated with any dry contact switch (mat, PIR, manual switch etc) as long as no voltage goes to the player. I'll have the circuit for turning it off in a another week or so. I'm getting the circuit drawings done as I go, and will include pics. The first timing circuit looks a bit sloppy - a couple of false starts, and I'm not the best at circuit board layouts. Progress is being made! More to come...
 

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Otaku; As you know from my various pleas for help, I've been playing with one of these units, and I noticed that once recorded, they will play a constant loop. Will your "OFF" circuit have the ability to 'time' the play event? Just curious because I'm trying to run Stephen Lynch's "Halloween" through a Scary Terry setup and have'nt quite figured out how to stop at the song's end rather than have it immediately start to play again.
 

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A little bit bent...
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Discussion Starter #6
In a way. Right now, I'm planning to use a second timer circuit to control the power to the player. Both timers will start at the same time, but one stops after starting the player (~1.5 sec). The other timer stays on for the duration of the file, and will be controlled by a potentiometer. This means that you need to know the length of the file, and you'd need to play with the timer a bit to "dial in" the pot. Adding a short silence period at the end of the file will help in preventing restarts. I'm still trying to determine a way to monitor the playback IC so that it can be shut down at the end of the file, but can't find any info on the chip. I suspect that it has proprietary firmware in it as well.
 

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A little bit bent...
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Discussion Starter #7
Whew! OK, I built and tested a 556 timer circuit that lets me turn on the MP3 player, play the file once, and shut down the power supply to the player when the file is finished playing. The next trigger event starts the whole thing over again. This circuit is pretty much a prototype, so is a bit messy. I also plan to use a different board (easier to use) for the next builds, so I'll start the how-to picture fest when I get the new parts. The bottom line is that one can now turn these players on and off remotely, with the event controller of your choice.
 

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I take it, these have good sound quality? I was thinking about getting some cowlacious recorders at some time, but if these are nice....

Adding a couple more relays to one of my prop controllers wouldn't be a big deal. What do you guys use for amplified speakers? I was checking out Radio Shack's MP3 portable speaker for $5.97. Their item # 10-1469
 

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Discussion Starter #9
These players have very good sound quality, and you get the bonus of stereo tracks. The ISD chips in the Scary Terry boards can only record mono. They hold several minutes of sound, depending on the bitrate used in the file (Dennis at Wolfstone estimates that at certain rates, the player will hold ~30 mins). For $5 each they're hard to beat, especially if you're planning a looping soundtrack.
 

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They seem to play well on just about any decent set of amplified computer speakers Bourno, I'm using one on a Scary Terry skull with a split track and had to modify a set of speakers into an amplified mono-setup and it turned out well. You will be really surprised how well these little mp3's record and play! And yes, we love Otaku!
 

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Yeah thanks Otaku. You've just given me the power of great sound quality at even lower cost than a chipcorder. :D
 

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Discussion Starter #13
It'll take a couple of weeks to get a good how-to together for this hack. I'm still in the R&D stage, and am looking for the best board to make the timer assembly easy. The concept is proven, however, and I just need a solid parts list. I'm trying to single-source all the parts. I have the circuit drawing, but its in a .doc format so I can't attach it to a post. If anyone wants a copy, PM me and I'll email to you. Please note that I may be changing the values of the 470 uF cap and the 1 MOhm pot - I'm still experimenting with this part.
 

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Discussion Starter #14 (Edited)
OK, I have the circuit worked out. The values of the 1 Meg potentiometer, the 1K resistor and the 470 uF cap can be varied to change the timing period. I'm still working out the how-to, but here's a drawing of the circuit. The remainder of the circuit that connects the relays to the USB connector and the MP3 play button are in the works and I'll post it soon.
 

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OK, I have the circuit worked out. The values of the 1 Meg potentiometer, the 1K resistor and the 470 uF cap can be varied to change the timing period. I'm still working out the how-to, but here's a drawing of the circuit. The remainder of the circuit that connects the relays to the USB connector and the MP3 play button are in the works and I'll post it soon.
Otaku,

Before I make any suggestions, i just want to say I think what your doing is great! I don't want to come off as negative, but I have a few questions and suggestions for your circuit.

I am questioning why you have output pin 9 "sinking current" and output pin 5 "sourcing" current. Please keep in mind that the 555/556 can only sink/source up to 200mA of current when choosing your relay. The ouput pins will only go so "low" depending on how much current you "sink". It would probably be better to "source" the current in both cases.

In any case, the "sorcing" output pins will need some additional diodes. Since the relay coil is "inductive" you should place a rectifying diode (1N4001) in series with the output pin and the coil to ensure that a small 'glitch' cannot be fed back into the IC. Without this extra diode monostable circuits may re-trigger themselves as the coil is switched off. Also, a standard protection diode (1N4148) should be connected "backwards" across the the relay coil.

These additions to your circuit will avoid false triggers and preserve the life of the 556 timer.

I think I may try this myself. I can't wait for the how-to! Thanks again.
 

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A little bit bent...
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Discussion Starter #17
gmacted,
Thanks for the suggestions. I had seen the use of the diodes on some circuit drawings, and was thinking about doing that myself. As regards pins 5 & 9, the wiring is as found on several circuit examples I looked up on the web. I am paying attention to the current requirements of the relays I'm choosing, and will keep the coil current demand low (< 100 mA). More to come...
 

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gmacted,
Thanks for the suggestions. I had seen the use of the diodes on some circuit drawings, and was thinking about doing that myself. As regards pins 5 & 9, the wiring is as found on several circuit examples I looked up on the web. I am paying attention to the current requirements of the relays I'm choosing, and will keep the coil current demand low (< 100 mA). More to come...
Please keep in mind that the more current that you sink, the less close the output pin will go to a low (or 0V). When sinking 10 mA, the ouput will go down to 0.1V. When sinking 100 mA, the output will only go down to 1V. They relay should still engage, but just keep that in mind. The 555/556 is much more stable when sourcing current.

Keep up the good work!
 

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A little bit bent...
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Discussion Starter #19 (Edited)
Here's the latest revision of the timer circuit. I still have to draw the power connections to the USB connector and the player start button wiring. Many thanks to gmacted for his valuable advice on the addition of protection diodes. I'll try to get a pic of the start button wiring up later today.
 

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Here's the latest revision of the timer circuit. I still have to draw the power connections to the USB connector and the player start button wiring. Many thanks to gmacted for his valuable advice on the addition of protection diodes. I'll try to get a pic of the start button wiring up later today.
Looks good Otaku. One little mistake I noticed. You have the 1N4001 diode for the bottom relay incorrect. It should be connected to pin 5. The whole purpose of the diode is to protect the IC.

Everyone better hurry up and buy those MP3 players! With this how-to they may sell like hotcakes!
 
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