Introduction: The 555 Light Theremin
Quick! Make a Tight, Light-controlled tone generator! It's a fun to build little devise that can be made out of easy to find electronic components! Even better is that it has a cool name! The "Light Theremin" (Th-air-ah-min) that I will be showing you how to make today is a tone generator who's pitch varies directly with its light input.
I would suggest putting this project together on a breadboard first and then soldering it up on perfboard if you enjoy it!
Step 1: Do You Have the Parts?
The necessary parts:
* Small wires for making connections
* Female RCA (TV cable) adapter. I use these for power input on all of my soldered-up projects.
* Female headphone jack (1/8 in. / 3.5mm.)
* Phototransistor. THIS IS NOT AN LED
* 10,000pf ceramic capacitor. #103. This is the same as 0.01uf or 10nf
* 4 different valued resistors. 4.7 Kilohm, 10 Kilohm, 22 Kilohm, and 10 Megohm
* NPN transistor
* 555 timer IC (integrated circuit)
* DIP-8 (dual in-line package - 8) IC socket
****If you don't know where to find these things, head on over to MOUSER.com and search for them! make sure to look at the datasheet of each item before ordering!****
****Note that both the DIP-8 IC socket and the female RCA adapter plug are unnecessary for building this project on a breadboard.
Step 2: These Are NOT LED's!
THESE ARE NOT LED's!!!!
These are PHOTOTRANSISTORS.
Don't mistake these for LEDs. They look essentially identical, but they work in the opposite fashion.
LED's emit light, whereas phototransistors absorb light to control the flow of electricity.
The phototransistor is what makes our Tight Light Theremin work! Tightly!
Step 3: Put It Together! Schematic
As with all of my electrical inst'ables, I include a link to the HD-ish picture of the schematic!
*** How does this work? The 555 timer's tone that it creates varies it's pitch based on resistor and capacitor values. The phototransistor controls how much current can pass from the collector of the NPN transistor to the emitter of the NPN transistor, sort of like a resistor.
*** The output of the 555 is connected to the headphone jack and in turn is heard as an audible tone when listening with earbuds or headphones. Depending on how much impedance your earbuds/headphones have, you may have to fiddle around with the value of the 22 Kilohm resistor.
Step 4: Final Step!!
Now that we have our Light Theremin all put together on a breadboard and well played with, what can we do with it?
I will admit that there is no real practical application for a light theremin. The only thing I can think of is just a little bit of fun once in a while. But all in all, that is pretty TIGHT!!!
Now solder it up! Show it to your friends! And for the love of god,
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