Play Audio While Wheel Spins

Thread Starter

Matt Pierce

Joined Feb 24, 2018
2
Alright, there's no simple way to explain what I'm trying to do, so hang in there with me.

I'm building a table, designed to look like Pac-Man (yes, really), and it has a lazy susan dead center. It will be a sheet of plexiglass routed into a piece of wood with the bearing assembly attached to it. I have this delusional fantasy that when the lazy susan spins, the table will go "wacka-wacka-wacka" for the duration of it spinning. I've hit a dead end on how to make this work, so I am reaching out for ideas. Feel free to ask questions, mock, or provide any information you think might be helpful. Thanks again!
 

Tonyr1084

Joined Sep 24, 2015
5,211
What comes to my mind is a small DC motor connected via a belt to your lazy Susan so that when you spin it the motor generates a small voltage. That voltage can be fed to a comparator. When the motor voltage exceeds a preset level the comparator can output a high signal that can then switch on your recorded sound. Now, exactly how you want to generate the waka-waka-waka sound, there are plenty of options. DNA Robotics suggests something pre-recorded and digitized so that when the comparator senses motion it turns on the recording. When the wheel stops turning the comparator shuts the recording off.

You might be able to find a ring tone that sounds like pac-man and upload that to a memory chip so that when your amplifier plays the sound it plays from that ring tone. The sweet thing about that is you can change the sound to anything you like. Flatulence is the first thing that comes to my silly mind, but then again I'm known among my friends to be "The Weird One".

I'm sure there are other ways to generate the signal as well. Using a reed switch and magnets or a hall effects transistor are decent ideas, but you might use them to trigger a 10 second sound. But the wheel might only spin for 3 seconds. Children may sit there and play with the wheel and spin it and spin it and spin it just to make it make that funny sound. So if it plays for 10 seconds then it needs to be re-triggered somehow. That's not a difficult thing to do, but it does require a little more circuitry than a comparator who's job is to sense a voltage above a set threshold.

Would love to see a video of it when it's done.
 

dendad

Joined Feb 20, 2016
3,611
The motor is a good idea. But instead of a DC motor, an old stepper from a trashed printer may be a better one to go with as there are no brushes to worry about. And as a bridge rectifier will be needed anyway, the DC motor polarity reverses with direction, just rectifying the stepper AC out and feeding that DC to a schmitt trigger circuit to start the sound chip running should work ok. I have used the WT588D chips
https://www.ebay.com.au/itm/Interfa...hash=item2cbe0ccb44:m:m-R9WUafL4ttLDBhjFzvP5w
 

Tonyr1084

Joined Sep 24, 2015
5,211
Hadn't thought about rectification. Good point. But your link doesn't post to certain countries:

Item location: ShenZhen, China
Posting to: Worldwide

Excludes: United Kingdom, Hong Kong, Macau, Taiwan, United States, Qatar, China

So if the TS lives in any of those countries then he/she can't get them. Not this particular ebay item anyway.
 

dendad

Joined Feb 20, 2016
3,611
Hadn't thought about rectification. Good point. But your link doesn't post to certain countries:

Item location: ShenZhen, China
Posting to: Worldwide

Excludes: United Kingdom, Hong Kong, Macau, Taiwan, United States, Qatar, China

So if the TS lives in any of those countries then he/she can't get them. Not this particular ebay item anyway.
That's ok. Just search Ebay or other shops for "WT588D" and you can see a selection of boards. I use the version that needs to be plugged into a programmer but the bigger boards have built in USB. Mine are in a Nerf gun modified to be a Laser Tag gun. We are in the process of building a sytem.
 

Bernard

Joined Aug 7, 2008
5,681
Might try a black & white pattern around disc edge read with reflective sensor. Use a 555 as a speaker driver.
Sound might be more of a Plunk-plunk.
 

MisterBill2

Joined Jan 23, 2018
7,257
Might try a black & white pattern around disc edge read with reflective sensor. Use a 555 as a speaker driver.
Sound might be more of a Plunk-plunk.
The black/white idea can work very well, I have used it to read speed of a mag-lev device using IR led and an IR phototransister. Even at one inch it still worked, at 1/4 inch it was perfect. Also fairly cheap.And that square wave could repeatedly trigger a one-shot and the output would stay high until the thing reached some arbitrarily set slow speed. generating that wka-waka sound is a separate challenge.
 

AnalogKid

Joined Aug 1, 2013
8,680
when the lazy susan spins, the table will go "wacka-wacka-wacka" for the duration of it spinning.
Are you talking about

1. playing a captured "whacka" sound clip repeatedly, at a slower and slower rate as the table slows down?

2. an electronically generated sound like something out of an old drum synthesizer?

ak
 

Tonyr1084

Joined Sep 24, 2015
5,211
WOW! Didn't realize how annoying those sounds were. Glad I can click to pause them. 12 hour version of waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-waka-

NO WAY JOSE!
 

Thread Starter

Matt Pierce

Joined Feb 24, 2018
2
As a relatively simple carpenter, I'm seeing that this is way over my head. Is there a dumbed down version of what you guys are talking about that you might recommend? I was thinking about buying some toy that makes sound when it's wheels spin or something and somehow install it where it spins as the glass spins, and somehow replace the existing sound with a new one to cause the continuous Wacka Wacka sound as it spins. That may not be as simple as it sounds, however.
 

MisterBill2

Joined Jan 23, 2018
7,257
As a relatively simple carpenter, I'm seeing that this is way over my head. Is there a dumbed down version of what you guys are talking about that you might recommend? I was thinking about buying some toy that makes sound when it's wheels spin or something and somehow install it where it spins as the glass spins, and somehow replace the existing sound with a new one to cause the continuous Wacka Wacka sound as it spins. That may not be as simple as it sounds, however.
Matt, the really complicated part is the making it slow down as the spinning slows. But now here is an idea straight from 1969: Use a tape loop and the electronics from one of those old reel drive tape recorders.You would need to extend the shaft down and put a pulley created for the 1/4 inch tape on it, and you would need to record the sound onto the tape before putting it into a loop. A second pulley would allow the loop to be stretched sort of snug, and the tape head would then need to be mounted to pick up the recorded track. The sound speed would then match the rotation speed exactly. The electronics would be ready made and the hookup would be simple, and it could run on a single 9 volt battery.
 

Tonyr1084

Joined Sep 24, 2015
5,211
Well, maybe here's a woodworkers solution to the desired result: Make a pulley and a cam (or crank shaft) that moves a stylus across a plastic comb. As the wheel turns the crank moves the stylus (needle of some sort) across the comb and you kind of get a waka-waka sound. I'd think. You'd have to experiment with it. But it will never need batteries, nor will it need to be plugged in. I don't think I can come up with anything easier. maybe vary the type of comb or make something wooden with varying lengths of wood slats that as the stylus crosses them they make some sort of sound. You might even be able to build a reverberation chamber (small hollow box of a specific size to match the sound) to make it louder. Look into how the Cuckoo clock makes its cuckoo-cuckoo sound. Basically they're bellows that blow a small whistle. The reverberation chamber makes it much louder.

For an example of how the comb would sound, just rub your finger nails across the ends of the comb fronds. Different types of combs, different sounds. The small black ones that you keep in your back pocket (well, we did when we were kids - about a hundred years ago) are the kind I think will come closest to the sound you want.
 
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