# Adding Sound to Props



## Abunai (Oct 28, 2007)

I want to add sounds to some of my animated props this year. I have a pneumatic Alien that would be ten times scarier if it screamed at the ToTs as it jumped out at them. 

I have seen the Cowlacious chipcorder boards, but I am, at heart, a cheap skate. Has anyone come up with a good way to get good sound on the cheap?

I would love to find a triggered, repeatable sound player. Variable sound duration would be excellent. I don't want to be locked into 30 seconds, or a minute, or any fixed length of time. 

I am proficient with electronics, so don't hold back on any schematics or other detailed descriptions.


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## Otaku (Dec 3, 2004)

How cheap is cheap LOL? And how do you want to trigger the player? For example, if the prop moves you can use a small snap switch mounted so that the moving prop hits the switch. Digital sound chips can't be re-triggered until they finish playback, so multiple hits are no problem. Also, many cheap MP3 players can be hacked to allow remote triggering. I designed a timer circuit that can trigger a hacked MP3 player to play back a file then shut down until needed. Here's the link to the how-to:

http://www.teambac.com/web_hall/mp3_player/otaku/MP3_player.html

This circuit may work for other MP3 players, depending on how the playback is initiated, and the accessibility of the USB connector. The MP3 player I used in the circuit is not available from MPJA any more - they sold out of them.


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## Abunai (Oct 28, 2007)

Yeah, I guess "cheap" is relative. In a perfect world, $20 to $30 per unit would about fit my budget. 

Any player that could be triggered with a contact closure would work. It would be easy to adapt to any number of triggering methods (pressure mat, motion detector, remote, etc.)

So, in your design, the MP3 player is powered on, allowed to play for a set amount of time, then power is removed? (I have to admit that I haven't yet read all three pages of your write up...I will though.) I assume that you take the line out audio and plug it into a set of powered speakers, like computer speakers?


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## Otaku (Dec 3, 2004)

Yes, that's how the timer works. The playback time length is set by the potentiometer. While the file is playing the timer can't be re-triggered, and if you use an MP3 editing program like Goldwave or Audacity, you can add a period of silence to the end of the file to act as a delay before retriggering. Helpful if you're using a mat or non-timed PIR to start the player. The downside is that it's built around the $5 MP3 player that isn't easily available anymore. With a bit of hacking, you should be able to adapt most cheap MP3 players to work with the circuit, depending on what is needed to initiate playback.

BTW, Jeff at www.simplecircuitboards.com has commercialized this circuit. He has 3-4 different versions of the board, one of which is is a player only. It does require getting the programming board to set the play time into the chip, but I think the playback boards are less than $30 each. After you program the player board, you disconnect it from the programming board and it operates as a standalone. Drop him an email if you want to get more info. In case you're wondering, I don't get anything from the sales of the boards.


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## gmacted (Jan 18, 2006)

Abunai,

I built a circuit very similar to Otaku's, but with a few modifications/enhancements (The circuit is triggered by a PIR and the entire circuit including the MP3 player and PIR operate on a single 9V battery.). I created a schematic that contains all the technical details along with a detailed parts list.

Here are a couple of pictures of the final product. These pictures were taken at the Massachusetts make and take held in January of 2008.

MAkenTake :: DSC01024.jpg picture by monsterguts - Photobucket

MA Make and Take 1 :: The circuit that drives the MP3 Player/PIR circuit picture by Zombie-F - Photobucket

MA Make and Take 1 :: gmacted's PIR/hacked usb MP3 Player for show and tell picture by Zombie-F - Photobucket

If you're interested, send me a PM and I can send you the schematic.


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## JonnyMac (Apr 5, 2007)

Full disclosure: I work for EFX-TEK.

While I absolutely appreciate those who build custom circuits (I've built thousands in my life/profession), there comes a time of diminishing returns on one's time. You could in fact use our Prop-1 controller to monitor sensors, trigger and time the MP3 player, and do other things. The down-side is that it costs more in $, the up-side is that is saves you hours of time in circuit construction, and even better it can be re-configured (via programming) for new behaviors, or even moved to a completely different prop. One of the really cool aspects of a programmable controller is the ability to use a randomized hold-off between the trigger input and the prop sequencing.


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## gmacted (Jan 18, 2006)

JonnyMac said:


> Full disclosure: I work for EFX-TEK.
> 
> While I absolutely appreciate those who build custom circuits (I've built thousands in my life/profession), there comes a time of diminishing returns on one's time. You could in fact use our Prop-1 controller to monitor sensors, trigger and time the MP3 player, and do other things. The down-side is that it costs more in $, the up-side is that is saves you hours of time in circuit construction, and even better it can be re-configured (via programming) for new behaviors, or even moved to a completely different prop. One of the really cool aspects of a programmable controller is the ability to use a randomized hold-off between the trigger input and the prop sequencing.


Full disclosure: I am not affiliated with EFX-TEK in any way.

I agree.

I have used a prop-1 in past projects and it works great and as far as I'm concerned Jon and the EFX-TEK team deserve a lot of credit for their fantastic customer service. I have worked with no other company that provides better service than EFX-TEK.

This project could also be completed with a prop-1. You would still need some external circuitry in this case, but it would be considerably less.

I had thought of using a prop-1, but my main goal was to operate this circuit with only a 9V battery and not rely on AC voltage at all. I'm not 100% sure what the current draw of the prop-1 is, but I ran my circuit for several hours with just a 9V battery and it worked great. It may not have the versatility of the prop-1, but it gets the job done.

From a cost perspective, the prop-1 is hard to beat. Considering the cost of materials and time, building your own circuit usually isn't worth it and in this case it's probably close to a wash.

Based on my past experience, there are many people on this forum (including myself) who do not want to re-invent the wheel. They want something that works with a "how-to". In this case, I have a circuit that works and all the person needs to do buy the material, build it (hopefully with little to no debug) and use it. There may be no such thing, in this case, for the prop-1. There will most likely be a learning curve which they may not be willing to do.

Case in point. EFX-TEK sells an led flicker circuit at Halloween, where the user just buys the kit, plugs it in and it works. They could do it themselves, just most people choose not to.

Jon,
There appears to be a lot of demand for this type of on-demand, MP3 quality sound. Make a kit at a reasonable cost and people will buy it.

I understand the AP-8 somewhat fits into this model, but to be honest, the sound quality isn't that great, it's not stereo, and the price isn't all that attractive.

Don't get me wrong I have used the prop-1 and the AP-8 and they work great together, but most users want something less expensive that's "turn-key".

I am well aware that cost is relative and is based on perspective. From most home haunters perspective, time is free (especially at this time of year), so a couple of inexpensive components and a soldering iron will, in their eyes, cost less. In the long run, it may not be, but that initial thought is what drives their decision.

I think EFX-TEK has a very good business model. Provide the user with a relatively small product set that can accomplish many things (It's only limit is the users imagination.). EFX-TEK then provides excellent technical support and the user accomplishes his/her goal. Using this model EFX-TEK does not have to produce any customized products, but gets a good reputation based on users feedback. The only problem with this model is that Jon doesn't get a lot of sleep at busy times of the year.


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## Phil (Sep 2, 2007)

Abunai, if poor audio quality doesn't turn you off, there is always the Radio Shack recording module at $11. Sure, it sounds like a telephone and is limited to something like 20 seconds but it is cheap, repeatable and pretty darn simple to modify. I wired two for external trigger, added mono-mini jacks for output to an amp, and power them at 5VDC to save on batteries. Not the caliber of an EFX-TEK product, but you said you were cheap...


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## Death Master (Jul 1, 2007)

On my stand alone Props I use a hacked MP3 player ($8), a 22 Watt amp ($14.50), and a cube speaker (5$), the sound quality is excellent, and boy is it loud.


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## Abunai (Oct 28, 2007)

Thanks, everyone, for the input. I think that I will go the hacked MP3 player route. If we do get a group buy together, I'll purchase several. 

JohnyMac, have you guys ever thought of creating a simple GUI application for your Prop-1 board that will allow users to specify the behavior of each I/O pin? Kind of a 4GL interface that is user friendly, and generates the necessary code for the Basic Stamp? Also, I am new to microcontrollers, but how does the Basic Stamp compare to the PIC 24, capability wise?


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## JonnyMac (Apr 5, 2007)

Abunai,

GUIs tend to defeat the versatility of most controllers -- that said, we actually worked with a guy named KC Oaks to create add-ins for his freeware (haunters love free) program, Vixen, to turn it into a simple sequencer (like the "brick" type products) for the Prop-1 and Prop-2. There are details in our support forums:

http://www.efx-tek.com/php/smf/index.php?topic=140.0

This allows a non-programmer to create simple sequences, and this is really where most haunters want to go; we're pretty sure of that because we've had an enormous amount of positive feedback. The great thing is that once one understands what a programmable controller can do, one can jump into programming and the product they have in had (Prop-1 or Prop-2) will support that. Other "brick" controllers are simply sequencers and cannot be reprogrammed to behave differently.

The Prop-1 uses the BS1 which is a PIC16C56 with a Parallax BASIC interpreter built in. So, it's a much older PIC and you cannot program it in Assembly. Most haunters don't know what assembly is, let alone want to learn to do it. For those that do, we have the Prop-SX which uses a raw SX28 (i.e., there is no interpreter of any kind built in).

The SX is a fairly straightforward micro, can be programmed in the language of your choice, and it screaming fast (75 MIPS). I've been doing DMX applications for a large amusement/entertainment company here in SoCal and they're very happy: they simply stock the Prop-SX and load it with the application of their choice. Our RS-485/DMX-512 (coming soon) board will also allow the Prop-SX to act as a smart node in a networked control system. If you're interested in low-level micros you might consider starting with the SX as the cost of entry is very low (see Parallax.com for their SX products).

I'm sure we lost a bunch of members in the last paragraph, so I'll leave it at that.


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## tonguesandwich (Oct 13, 2006)

Any disadvantage starting with a prop-2 kit instead on the 1?


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## JonnyMac (Apr 5, 2007)

No; the Prop-2 costs more but has more I/O, more programming space, and is about 5x faster. In fact, some consider PBASIC 2 a little easier to learn because it seems more like the BASIC variants found on PCs.


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## tonguesandwich (Oct 13, 2006)

OK thanks.... can you give some real scenario samples of what a SX can do that a prop 2 can't do. Should one just skip the first 2? Just start with a SX. Sorry, very slow learner.


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## grimshady (Feb 12, 2008)

Some folks have used these bad boys to get great stereo sound.
http://www.roguerobotics.com/
They cost too much but they are great!!

I use the scary terry audio chipcorder boards. The quality is not super but hey, when your just pumping out a scream or moan, it might not be that important.

More important is the audio amp you use. I have found that cheap electric guitar amps are the ticket here. 40 or 50 bucks for an amp that will be very loud.


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## Abunai (Oct 28, 2007)

Otaku, 

OK. I was able to buy 5 pair of computer system speakers ($3 each) and 5, 128MB MP3 players ($9 each) and I am ready to start working on this. 

I don't know yet whether I will use your circuit, or the Prop 1. I know that the Prop 1 will allow me to define a timer in code, and trigger the MP3 player. 

I do have some "theory" questions about the whole setup, though: 

You have a picture showing where you connected the leads on the MP3 player model that you hacked. What points are those, the Play button? (I am going to hack a Macvision model MA833A player.)

What is the purpose of connecting via USB? What implications does that have if I use the Prop 1?

A general description of the theory behind the this setup would be much appreciated.


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## Revenant (Mar 17, 2007)

Another note on sound improvement: One of the haunters on here built an acoustic wave guide (sort of a bathtub Bose system) to enrich the sound from a crappy little speaker and make it rich and resonant. Run mono sound through 2 speakers, and mount each speaker at the end of a piece of pipe, one exactly 3 times the length of the other, and have the open "exit" ends next to each other. This provides a lot of resonance, which is what "de-flattens" sound and makes it sound more organic.

The thread is here; but the link to the diagram is gone. As I recall I think he rewired one of the speakers so they were in opposite polarity to each other; not sure exactly what that does but apparently it's important. Something to do with constructive wave interference or something like that I think.


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## Otaku (Dec 3, 2004)

Abunai said:


> You have a picture showing where you connected the leads on the MP3 player model that you hacked. What points are those, the Play button? (I am going to hack a Macvision model MA833A player.)
> 
> What is the purpose of connecting via USB? What implications does that have if I use the Prop 1?
> 
> A general description of the theory behind the this setup would be much appreciated.


Abunai,
Yes, the two wires in the picture are connected to the Play button. That's the button you have to hold for ~1 sec. to start playback.

The reason for the USB-A connector on the circuit board is to simplify the power connection for the player. The ones I used run on 1.5 VDC so the AA battery is wired to pins 1 and 4 (I think). The cheapo players use an external battery pack, so if your player uses internally wired power, you'll need to figure out how to shut off the power (or otherwise turn off the player) at the end of the file. I can think of a couple of ways to do this using an astable timer circuit, but again I don't know how your player accesses power.
The general idea here was to be able to start the playback by shorting the Start button for the appropriate length of time. Power is applied to the player at the same time. The time that the player stays on is determined by adjusting how long the power stays on. When the timer supplying power to the player runs out, the playback stops. The power timer also locks out the triggering timer and prevents re-triggering during playback.

I hope this helps. Please let me know if you have any other questions.


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## Abunai (Oct 28, 2007)

Otaku, 

I think that I lucked out then. With the MP3 players that I bought, I can keep them powered on, and as long as I only have one sound file on the player, every time I hit the play button, the file will play. 

It looks like I won't have to worry about a timer at all, just some sort of triggering scheme. Shouldn't be hard at all.

Thanks for your help.


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## Otaku (Dec 3, 2004)

Cool! The reason for the power-on timer in the circuit was to prevent looping of the file. The cheapo players will immediately replay after a file has ended, so you need to shut off the power. The good thing about that is they work very well for soundscapes and repeating background sounds. Just set 'em and forget 'em.
For triggering your players: do you need to press and hold the Play button for some length of time to initiate playback? If so, you'll need some sort of timer function to keep the button "down" for that period. A Prop-1 should handle that nicely, as well as being able to accept the trigger input of your choice. Can the Prop-1 be programmed to not accept the next trigger event until, say, 30 seconds has elapsed?


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## JonnyMac (Apr 5, 2007)

Yes, the Prop-1 can ignore triggers after a valid one has been received -- very easily. One could easily structure a program like this:

A) Wait for trigger
B) "Press" play button (activate output)
C) Wait 2 seconds
D) Release "Play" button (deactivate output)
E) Wait 28 seconds
F) Go back to Step A

In this case the program would not start looking for another trigger until 30 seconds (2 + 28) had elapsed since the detection of the previous trigger event.

Better yet, the controller could be cycling the other outputs that are in sync with the audio; coordinated sound, lighting, and movement is always a good thing.


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## JonnyMac (Apr 5, 2007)

tonguesandwich said:


> OK thanks.... can you give some real scenario samples of what a SX can do that a prop 2 can't do. Should one just skip the first 2? Just start with a SX. Sorry, very slow learner.


Well, the Prop-SX runs a whole lot faster than the Prop-2 because it's running compiled (machine) code, not a basic interpreter. Since it runs machine code you can program it in any language that's available for the SX: Assembly, BASIC (we use SX/B -- I helped create it), or C (there's a free C compiler that seems to be gaining popularity).

The Prop-2, by it's nature, is single threaded. That doesn't mean you can't "fake" multi-tasking, but you have to do it at a pace that controllers consider slow. Just yesterday I finished a very sophisticated program for a shooting gallery that has three pop-up pygmies that shoot blow-guns (nothing comes out except air). The designer wanted the pygmies to behave completely randomly of each other -- as if each was running on its own controller. One has to resort to state-machine programming for that; in the end that program works well.

But what if I wanted to run pygmies and receive serial data at the same timer? Or fade LEDs? -- the Prop-2 is not fast enough to handle this, the Prop-SX is. I've been doing a lot of work with a big amusement/entertainment company because they need specialized DMX-512 slaves for various projects in their parks. With the Prop-SX we were able to create that. At present I have DMX programs to control relays (on/off), to fade LEDs (full off to full on in 255 steps) and to control servos.

Now... writing these kinds of programs is not for the beginner, but that's where we come in. Part of our package has always been custom programming support to whatever the user needs. Most of our older customers don't ask me to write programs for them anymore as they've finally picked it up. Like all the other technical skills we've learned vis-a-vis Halloween, programming is in fact just a skill, and I'm of the opinion that anyone can learn to do it.


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## Abunai (Oct 28, 2007)

No press and hold - just press. 

Yes, the Prop-1 could be programmed to do that. 

I wish that I had some more detailed technical information on the MP3 players. It would be very cool if there were a way to trigger 'play' through the USB port; then I wouldn't even have to open them up.


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## Otaku (Dec 3, 2004)

The cheapos that I use have two different modes - at 1.5VDC they act like an MP3 player, at 5VDC they are a USB device. Can your players be told to play when plugged into a USB port on your computer, and what command is used? If you have to open them (like an external drive) and select the file you want to play, then it could be a problem. If one file is on the player, and the commands are "Enter, Enter" and the file plays, then a hacked keyboard might be used to send the commands. Dr. Morbius did this for controlling a PSC board for his skull.

But I digress. I like the Prop-1 solution in that it gives you some other options. If all you want to do for the foreseeable future is activate sounds-on-demand in various locations, then the cheap timer solution may be your best bet. I use the timer I developed with cheap PIR sensors and MP3's. Works great. If one Prop-1 can handle multiple discrete triggers and outputs then it may be the way to go. Jon, your thoughts?


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## JonnyMac (Apr 5, 2007)

The Prop-1 has eight I/O points, you can slice-em and dice-em as you see fit. If you want to have different triggers trip different things I can show you how to do that -- within reason. The Prop-1 is a very small controller, and trying to run two independent props with it creates a bit of a programming challenge.

If you post an example question, "Hey, Jon, how would I code this?..." in our tech forums I'll give it a go -- then you can evaluate for yourself whether this is a road you want to travel or not.

forums.efx-tek.com

Jon Williams
EFX-TEK


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## Otaku (Dec 3, 2004)

I was thinking more of triggering several MP3 players from separate, dedicated trigger inputs. An example - I attach _n_ players to I/O points along with a dedicated trigger device (PIR, mat etc) for each player. The code for each I/O point is just a few lines and essentially identical; the Wait times may vary as required. The code would not necessarily be running simultaneously.


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## Dr Morbius (Sep 21, 2004)

Part of my control consol, which is VSA/PC based will use the Kit74 relay cards to trigger Mp3 players hacked at the play buttons to the relays. VSA would be programmed to trigger the players at various events. Probably not what you want to do, but I throw it in for what it's worth, I find that using old PC's running VSA is the simplest way to go for controlling..........anything.


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## JonnyMac (Apr 5, 2007)

Otaku said:


> I was thinking more of triggering several MP3 players from separate, dedicated trigger inputs. An example - I attach _n_ players to I/O points along with a dedicated trigger device (PIR, mat etc) for each player. The code for each I/O point is just a few lines and essentially identical; the Wait times may vary as required. The code would not necessarily be running simultaneously.


The great thing about programming is that you can control the behavior. With the Prop-1 you have eight I/O points so that would allow you to have four trigger inputs to control four MP3 players.

One programming scenario could wait for Trigger 1, play that player, then move on to Player 2, etc. This would create forced sequential control, but the initiation of a player is via trigger when it's "armed."

In other applications you might want them to run and time-out completely independently and [possibly] simultaneously -- this is possible to through what is called a state machine. Since there are only three states it's pretty easy; in fact, in order to prove that point I stopped typing here and wrote such a program:

http://www.efx-tek.com/php/smf/index.php?topic=514.0

Don't let the length fool you; it's simply 4x the same sort of state machine (one SM for each player). By using this approach you can control the length of each start output as well as how long the trigger will be ingored once started.


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