camera flash charge-up sound?

A quick google search didn’t turn up something, so I thought I’d ask here.

Does anyone know of a circuit to make that cool sound of a camera flash charging? I suppose I could rip up an actual flash, but I’d rather avoid that. And I don’t just want to play a recording of it, which I already have as my system beep on my computer.

We’re planning a robot costume for halloween, and I think that sound would be cool when triggered by something, like a candy collection door opening or something like that. It would give a sense of urgency to the treater to fill 'er up good. Not sure exactly, but I mention this because the thing would have to be safe as well as make the sound.

Thanks!

[edit to put a ? in the subject]

You just want a rising frequency audio output.

Get a NE555 oscillator generating the audio output. Then put a large capacitor (start with 47uF) from ground to the voltage controlled input and a resistor of something like 1M up to +. Then have a push button that shorts the capacitor out.
When pressed the capacitor has no charge on it an the oscillator runs at the lowest frequency as it charges the frequency of the audio increases until it reaches a maximum.

Ah, cool. I’ll look into that. I’ve read about 555s for a while, so I should finally learn about them.

Thanks!

You could also generate the sound in software with the Arduino. The frequency of the sound is related to the rate at which a capacitor charges.

You could use an analog output to generate the audio while you ramp up the output frequency at a rate simulating the charge rate of a capacitor.

Not to discourage you from learning about the 555 though, it’s a very useful chip (I’m using one as a Schmitt trigger to clean up an input for an Arduino interrupt input, very handy).