Hi - I'm looking to create a small device which emits an audible beep when shaken/moved. Currently I'm thinking of using a small vibration switch (though there may well be a better way - I'm new to this!), so presumably need a way to deal with switch bounce too? I want the device to be as small as possible, so am thinking power from a watch battery. The beep needs to be audible, but doesn't need to be too loud. Although it's not actually my use-case, the clearest way to describe my aim might be making something that functions like an electronic version of a hand bell. I would like to create a few versions which emit different pitch tones too. Does anyone have any advice that could get me started with designing the circuit? Thanks

 

Welcome to AAC.

Something like this should do. It's programmable (you can record sounds or verbiage or music). Replace the push button with your motion switch. I believe once activated it will play the sound through its entirety, thus eliminating the issue with debouncing the vibration switch.

It's bigger than you want though.

 

If the intention is to produce some sort of musical device, such as an electronic hand-bell equivalent, but a bit different, then small size and light weight matter a whole lot. Battery power will also affect the size a whole lot. And whatever is used to convert the electrical signal into audible sound over a range of frequencies will be the major challenge. The amplitude of the "beep" will require power, and so probably a watch battery will not be adequate. There are published circuits utilizing UNIJUNCTION transistors that will probably be the simplest adequate oscillator, not using any transformer or inductive device. ONE project like that comes to mind, a "UNITONE" musical device. That article was published a long time back, but it might still be available someplace.
The trigger switch will also be a challenge, since mercury capsule switches are probably no longer available.

 

If the intention is to produce some sort of musical device, such as an electronic hand-bell equivalent, but a bit different, then small size and light weight matter a whole lot. Battery power will also affect the size a whole lot.

I agree but disagree at the same time. We've all seen those musical greeting cards where you open the card and it plays a pre-recorded song or message. I took one of those old cards and put a new CR2032 battery in it (larger than most watch batteries), clipped out the electronics and taped it under my bosses desk. Connected a tether to the piece of card that held the battery isolated from the electronics. When he opened his drawer the card began playing. It was "Rosanne Rosanna Danna talking about endangered feces". Now, it just so happened that shortly after setting him up for this April 1st joke a visitor from the home office came to see him. Naturally he needed a document he kept in his drawer. When he opened it - well, you can guess the rest.

Yes, size matters. If you want to build something the size of a sharpie pen you're going to have to get very very creative. But if you want off the shelf stuff, there ARE solutions. And as @MisterBill2 mentioned, battery size is going to be important. If this is a rarely used device then you can get away with a small battery. Used a lot and a small battery will deplete quickly. And if you're going for any kind of serious volume, a small battery is virtually out of the question.

 

If the "Audible beep" needs to be a specific pitch then an adjustable oscillator seems like the best choice, and I am guessing that a unijunction oscillator will be a smaller package and more adjustable than a programmed device. Also probably more available and less expensive.

 

Hi - I'm looking to create a small device which emits an audible beep when shaken/moved. Currently I'm thinking of using a small vibration switch

One solution using a vibration sensor and a small piezo beeper. Circuit draws zero current until activated by the sensor.
R3-C1 determine the beep duration. Circuit verified on the breadboard.

 

One vehicle security system that I recall investigating used what looked like a piezo sounder disk with a mass on a short lever soldered to it, to sense vehicle vibration and motion. That concept could be the simple sensor with an analog output.
Also, it seems to me that the TS is actually seeking to have the circuit produce a pitched note and not just some random beep sound.
So really, we need some additional description with greater detail for this interesting challenge.