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Discussion Starter · #1 ·
Hi,

Previously I made a post asking about compressors and noise towards some thought on adding them to a charity haunt I run. I can't get the pre-filled cannisters some suggested. So I went looking for some other ideas. I came across this YouTube clip of a "$5 prop". Looks good.. if I made a few of these and lay them out in a concentrated spot, I figure they could generate some good spooky sound (such as if they were all playing raptor sounds.. like a swam was coming at people through the corn stalks).

Thing is, I've never done small electrical soldering and assembly. This guys video shows the prop, lists the components. But it doesn't really give a good view of the bottom side of the board and his soldering work. Can anyone here provide a probable soldering map/image for what this assembly would be? Myself and others on the comment on his video have asked but he's never replied with that info. I have the parts, I just need to know how to connect them, and what to power it with. Any help appreciated, and I hope this in turn helps others who want to make this same handy little prop for just a few bucks.

Part 1 of his prop

Part 2 of his prop
 

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The problem with that setup is the timing. He's relying on the triggered output of the PIR to power the mp3 player for a specific amount of time which doesn't really work. You need a microcontroller in the circuit to do that reliably.
 

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Discussion Starter · #3 ·
But in video 2 you can see it is working.. and for me, running the sound for a brief time is just fine for the goal I have. But none of this I can even do without knowing what to solder to what. Hoping someone here with much more experience can share thoughts, an image, of how to do it, and what I would use for a power source. Could I just re-purpose an old cell phone charger for example? Or use one of those multi-volt adapters that have 3, 7.5, 9, 12v settings.. or could I even use some re-chargable batteries? I wish I knew much more about this to get started. But I need that start and can take on figuring out adjustments from there.
 

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The problem with trying to replicate this is that it requires an intermediate knowledge of electronic theory and a working knowledge of electronic components. The video gives a basic schematic layout of the components, but assumes you have that working knowledge of these components. Given these are all readily available you can look up the spec sheets and build you own schematic for review here and then start construction. Component pin/polarity labeling knowledge is essential to a working device. But all of this information is available. The 12V supply is used here for 3 purposes, the supply for the PIR sensor, the supply for the motor output, and the supply to the 5V regulator for the MP3 player. The motor output would be limited to the working current of the TIP31C, I would prefer to use that to pwr a relay. Anyway, you should explore more into the working theory of this build, good to expand you general knowledge before actually purchasing the components.
 

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Hi Envomni,

Welcome to the forum. I’d agree with J-Man and Alhgreg that this is not an ideal beginner project. In general for people getting started, I really like the Adafruit tutorials. Their Halloween Scream Box tutorial does the basics of what you are looking to do (hook up a PIR sensor to trigger playing an MP3). It’s well documented and has usually been tested by lots of others.

That being said, if you have the parts, You might as well try and put what you have together. The best way to learn is usually by getting your hands dirty.

At about 15 seconds in he does post a schematic of sorts.
Product Font Rectangle Parallel Screenshot


Fritzing is used by lots of hobbyists to show how the circuit would be laid out using a bread board. If you haven’t already, buy yourself a bread board, some jumper wires and pre-wired LEDs. Then start putting it together. If you get it working on the bread board, then you can start translating it to a soldered perf board.

I’m sure others would have better suggestions, but I would start with a 5v wall wart supply, the PIR and the pre-wired LED, get that working. I’m not sure which PIR sensor you have, but most will work fine with 5v. Then add your transistor and get that working with the LED. Test the MP3 player and speaker separately with the 5v supply. Then see if you can replace the LED with the MP3 player. If you stick with a 5V supply, you may be able to remove the 7805 voltage regulator and its capacitors. I’d leave the motor out of it. It doesn’t sound like your project needs it and will add electrical noise and kickback current that will need to be managed.

As an aside I rather like MOSFETS for switching DC power. Can often handle more power than the transistor, you can skip the resistor on the trigger, and they don’t add as much noise (both auditory and electrical) as relays.

Let us know how it goes!
 
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