In this instructable I will describe to  you how I made a solar powered prank for April fools day.

The goal of the device was to be at least 50% recycled materials and to cost no more then $5 per unit to make. As a side effect these devices can be mass produced for a larger distribution of the prank or to intensify it in one area.

The simplest idea that I came up with to meet these goals was to use a trashed solar garden light attached to a 3v piezo buzzer. When in the sun the device will produce a rather annoying buzz.

The solar cell from the garden light was removed and the housing and circuitry was retained for future use.

Before buying any additional part I did some research on how much power I  had to work with.

Using my multimeter in voltage mode I recorded an open circuit voltage of 2.8v in moderate light and 3.5v in full light.

Then I switched the multimeter over to current mode and measured the short circuit current to be 50ma in moderate sun and 75ma in bright sun.

Step 1: Purchasing parts

Knowing that my solar cell will output 3.5V at 75mA in bright light and 2.8v at 50mA, I purchased a radioshack part #273-0053 3V Mini Buzzer. ~$3.75

The specifications met the power supplied of the solar cell.
Voltage rating 1.5-3V
Current Consumption 15mA MAX at 3V

These numbers indicate that I could run 3 of the buzzers in parallel simultaneously off of one cell.
1 buzzer consumes 15mA.
The solar cell provides 50mA in moderate sun.
50mA / 15mA = 3 and 1/3 buzzers.

To keep things simple I stuck to one buzzer per unit.

For mounting purposes, I found a piece of scrap wire on the street. You could substitute any sort of wire including coat hanger wire.

Overall the bill of materials include:
1 X Solar Cell salvaged from solar garden light
1 X Piezo Buzzer
1 X Scrap wire

Tools to build this project are
A soldering iron
A glue gun
possibly a multimeter
To turn this idea on its head, you could replace the annoying buzzers with something that plays an actual &quot;note&quot;.<br /> <br /> Several of them hanging in a small copse, each playing a different note, could be rather pleasant.<br /> <br /> And for the intermittent idea, wouldn't a single flashing LED (FLED) do the trick?&nbsp; If you don't want it seen, wrap it in insulation tape.<br /> <br /> <br />
Sort of like smoke detectors that need new batteries? :P&nbsp;&nbsp; I have piezo buzzers that beep in short sequences... could one adapt BEAM technology to turn a solar engine or pummer into a beeping nuisance? I'll bet you can! It would store up energy and then release it at random, like a bird call. Put it into a plastic animal decoy that you have printed... or put it into a barbie doll and tape her to the tree with duct tape (over her mouth?). That ought to win a contest!
If your gonna store up energy and release it, use an alarm from a security system, loud and startling. <br> <br>Or servo + stick + pots and pans. <br> <br>Possibilities possibilities ....
Or make it sound like a cicada and do it in January.&nbsp; Would really blow someone's mind how you would have cicadas in winter.<br />
This one time, I heard a cricket on December 26 (and no, I had not been drinking... much)<br /> <br /> It was a fairly warm Dec. 26.<br /> <br /> The cricket was chirping reeeaalllyyy ssllooooooooowwwwlllyyyyy.<br />
ive heard u can tell the temp (dont remeber if in *F or *C) by how many chirp per minute/second
But it wouldn't be very funny if the sound was &quot;rather pleasant&quot;. Not really what I would call a prank.
That's why I said &quot;turn it on its head&quot; - from prank to artistic installation.
Ohhh, now I get it! Sorry...
Does a FLED pass current only when it is lit or is it constantly passing current?<br /> <br /> I will also look into something that plays a specific note. This is sounding more like urban sound graffiti!<br />
Current only when it flashes, I think.<br />
From some datasheets I saw . . . they pass a specif current when on and a lower current when off. <br /> <br /> BTW i saw a box of &quot;twinkling led christmas lights&quot; at BIG&nbsp;LOTS. It was advertised to be &quot;randomly&quot; twinkling which makkes me think that every led was a FLED. 60 lights for $10 so $0.60 per led and you dont have to wait for shipping<br />
When I first read your comment I thought it said corpse instead of copse. That would be an interesting prank.<br />
...and a slightly disturbing funeral.<br />
That would be fantastic.<br />
I guess it would depend on the funeral lol.<br />
i made one it is really annoying
How loud is it?
It depends on the piezo used but the one I used was audible for a good distance and fairly loud up close
Hmmm... if I&nbsp;try this, I think another possible placement for the device would be inside a light cover. When someone turns on the light, it starts buzzing, convincing them somethings wrong with the light.<br />
Thats a good one. I also found that on the outside face of drapes works good too.<br />
What about replacing the buzzer with the guts from an &quot;electronic birthday card&quot;?<br /> If that is possible, you could have a nice tune.
True but dont know about the power source of these. You may need to devise a cheap way to keep the voltage where it needs&nbsp; to be without it being too low when its not in bright light.<br />
I wouldn't worry about that too much.&nbsp; Those sorts of circuits only sound more &quot;interesting&quot; when the voltage is off spec.&nbsp; <br />
I'll definitely try it when I get one.<br />
Cool.&nbsp;&nbsp; I was just thinking of a talking Alvin (from that cruddy Chipmunks movie) that I found at the dump the other day.&nbsp; He's just crying out to be hacked for this or a similar project.&nbsp; The neat thing about it is that at full power he says &quot;hello gorgeous&quot;, but if you trigger him enough to run down the battery a bit, he just says &quot;Hell&quot;...<br />
5 stars, not only for having an original idea, but for using dell, windows FTW!<br />

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