I decided a fart piano would be a perfect gift for my kid sister, she'll find it immensely amusing. I search the net for circuits for organs and it's pretty easy to make one with a 555, a couple of buttons, resistors and a few capacitors, now that's fine I actually by this time kinda understand how it works, but what I don't understand is how to make fart sounds, I know its possible (

) just need some help. I am still pretty new to this awesome world of electronics, so be gentle please ;-)

 

You need to build a Theremin ....

http://m.instructables.com/id/How-To-Build-An-Optical-Theremin/

 

You need to build a Theremin ....

http://m.instructables.com/id/How-To-Build-An-Optical-Theremin/

does all theremin produce farting sound?

 

Theremin produces sounds at different frequencies and different tones,

 

Ha! A high-tech whoopie cushion.

My 7 yo daughter would love this!

 

joeyd, my kid sister is 7; the inspiration to this thread. I was thinking take http://www.instructables.com/id/How-To-Build-An-Optical-Theremin/ amd replace the phototransistors with normal transistor and an array of say 1k resistors and buttons that activate first button only first resistor, second button first and second resistor, etc?

 

Hello,

If you are looking for theremin schematics, have a look at the links of this page:
http://www.thereminworld.com/schematics

Bertus

 

Head over here for $hits and giggles. Or here. Or here.

No shortage of hot wind on the internet.

 

Head over here for $hits and giggles. Or here. Or here.

No shortage of hot wind on the internet.

ok, well if I want to use waveform samples for a synthesizer, well I can only fathom that it might be possible by using ?ATmega? microcontrollers and a bit of software, won't a theremin be easier and do much the same?

 

I found all those while searching for more basic information on what it takes to generate a realistic fart tone. I've never heard one. I was easily distracted by those sites and didn't find what I went looking for.

 

I found all those while searching for more basic information on what it takes to generate a realistic fart tone. I've never heard one.

Well....I suppose I could digitize one for you...

 

I found all those while searching for more basic information on what it takes to generate a realistic fart tone. I've never heard one. I was easily distracted by those sites and didn't find what I went looking for.

'cause the farting sound in the light theremin is a complex moving of shadows, not as easily implemented without the light bit as I first thought, how would you do it? and I'd like to fart "Jingle Bells"

The man in the video of the first post did it, so can we!

 

could someone guide me to a circuit that will "sweep" from one transistor to the next? both remain high and then first the one transistor goes low and then the other one after that... in series. in need of a bit of inspiration

 

I'm not sure what you're after but you might accomplish that with an oscillator (such as a 555 timer astable or an op-amp square wave) and a 4017 counter.

 

I'm not sure what you're after but you might accomplish that with an oscillator (such as a 555 timer astable or an op-amp square wave) and a 4017 counter.

http://www.instructables.com/id/How-To-Build-An-Optical-Theremin/

The guy moves his hand shedding light on the one optotransistor, then the other, and that produce a fart sound, if I can have a circuit that mimics that, but which frequency I can change, I can build a fart piano, hard wiring the setting that sets the speed of the motion.

 

Haha, well that actually is a pretty good fart sound! But you don't need a "digital" switch like I described, you need a fade. Maybe a very slow sawtooth wave from a 555 timer. The voltage on the timing capacitor is nearly a sawtooth. Then "mix" the sawtooth into that fart circuit to cause the fade.

You could have another timer slowly change the voltage on the control pin of the first timer, and this would introduce a bit of randomness into the effect. I use a 556, two timers in one package, when I want to do this.

 

Haha, well that actually is a pretty good fart sound! But you don't need a "digital" switch like I described, you need a fade. Maybe a very slow sawtooth wave from a 555 timer. The voltage on the timing capacitor is nearly a sawtooth. Then "mix" the sawtooth into that fart circuit to cause the fade.

You could have another timer slowly change the voltage on the control pin of the first timer, and this would introduce a bit of randomness into the effect. I use a 556, two timers in one package, when I want to do this.

2 problems: I don't know how to make a sawtooth, and I don't know how to "mix" it in. still very noob, this will be my third project, first was monostable multivibrator 555 doorbell, second was a datasheet job: a lm2576 buck for 36v input, now this fart piano is the funnest third project that will give my little sister hours of fun. So can you provide me with partial circuit diagrams? I'll hack my way through it, asking stupid questions along the way ;-)

 

Here's the schematic in that Instructable, taken from here. Now that I see how it works, I'm less sure of how to tweak it "automatically". It uses the phototransistors to alter the charge and discharge times of the timing capacitor C1. The farty sound seems to happen as the light fades across Q1 to Q2.

I'm at a loss how to simulate that at the moment.

 

Here's the schematic in that Instructable, taken from here. Now that I see how it works, I'm less sure of how to tweak it "automatically". It uses the phototransistors to alter the charge and discharge times of the timing capacitor C1. The farty sound seems to happen as the light fades across Q1 to Q2.

I'm at a loss how to simulate that at the moment.

View attachment 79540

Thats what I meant with sweeping, fading from one to another.

 

What's got me befuddled is that this circuit doesn't require a fading voltage (which is easy to produce), it requires a fading resistance. That's what the phototransistors are doing - changing resistance in response to light. There is such a thing as a voltage-controlled resistor. Maybe that would do the trick.