Electronics

The voodoo doll

This is a really quick one. I going through my electronic stuff looking for god knows what and discovered that I had some photo-resistors. So I decided to make a little prank for my room-mate (if you can call that a prank).

Because you see, he has such a charming “doll” (kinda) hanging on his wall.

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As you might have guessed from the picture, I want to give this marvel a pair of shiny red eyes. But since want the battery to last as long as possible (and play with a photo-resistor), they need to be made them so that they will only turn on at night.

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I soldered the photo-resistor to a transistor in order to reverse the logic (since the more light the resistance receives, the lower its value. What I want is to lower the value of the resistance when it gets dark, thus turning on the leds). Now, when it gets dark the resistor’s value lowers to a point where enough current goes through the gate of the transistor, enabling the current to flow from collector to emitter and to the leds.

Add two coins battery and we’re all set. Now to put it in place. I used a glue gun to stick it into the head (I use a glue gun to stick anything anywhere ; even my glasses hold together thanks to a bit of hot glue). Anyway, moving on to the result.

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Thank you for watching. We’ll come back after the break with even more useless projects !
(I’ve discovered the subreddit shitty robots recently and it is just great. So brace yourselves for a generation of useless thingy is coming !)

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