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Circuit Bending, Hardware-Hacking
Light Theremin |
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Control a sound making chip with light.
This is a recommended project from Make Magazine. http://makeprojects.com/Project/Light-Theremin/989/1 http://www.instructables.com/id/Light-Theremin/ and a mod: http://blog.makezine.com/archive/2011/11/weekend-projects-light-theremin-mod.html Parts: Resistor, 500-piece asortment, 1/4 Watt - Hookup wire, 22 AWG - Breadboard, small - Capacitor 0.22uF (220nF) (x2). You can also use one 0.47uF (470nF) (code 474) instead of two 0.22uF (code 224) caps in parallel. See here for help with farads (F), microfarads (uF), nanofarads(nF), and picofarads(pF)). See here for a capacitor code calculator. 1uF = 1000nF = 1000000pF = 0.000001F - Electrolytic Capacitor 100uF (code 107) - Speaker: 8 Ohms - Photoresistor, 5pk. You can also try using photodiodes, too. Experiment. - Battery holder, 4xAA, optional. Use this or other means of delivering 6v to the finished circuit - 555 timer IC 1 - Gather together the breadboard, capacitors, speaker, resistors and photoresistor (or photodiodes). The schematic I based this project on called for a 0.47uF capacitor. I didn't have any, so I used two 0.22uF capacitors in parallel. The values add, giving 0.44uF -- and that's close enough! We are going to be building a 555 timer-based "astable oscillator circuit." It sounds complicated, but really, it's not that hard. 2 - Install the 555 Chip and Power Lines Our first task is to place the 555 timer IC on the breadboard. Note the location of the small dot indentation (which I painted white to make it more visible). That dot always marks Pin 1 on a chip. I also added the basic power lines - red is +6v, and black is 0v (Gnd). The two red wires carry the power lines between the top and bottom horizontal power "rails" on the breadboard. 3 - Install the Resistors Breadboard the 10k ohms (Brown, Black, Orange, Gold) resistor at the top, and the 1MΩ (Brown, Black, Green, Gold) resistor at the bottom, as shown. Disregard the blue color of the 10K ohms here, your resistor will likely be beige in color. 4 - Add the Capacitors Add both 0.22uF capacitors in parallel. Be careful that the legs of the capacitors do not touch! Remember: I'm using two .22uF caps in place of the .47uF called for in the schematic. If you have a .47uF cap, you can use that. Also add support wires as shown (the two brown wires, and one white one). 5 - Install the Remainder of the Parts Add the 100uF electrolytic capacitor Note: Electrolytic capacitors are polarity sensitive. They can only safely go in one way. Note the orientation of the black band; it marks the negative lead. Add the speaker. Note the orientation of the red (+) and black (-) wires; it also needs to be connected with the correct polarity. Install the two photodiodes (second image). You should now be able to power up the device and hear a buzzing tone coming from the speaker. Move your fingers towards the photodiodes, and the pitch should go down. That's it! Move your fingers around the photodiodes to create different notes and sound effects. 6 - Experiment: Photodiodes vs. Photoresistors Photodiodes work in this circuit, but you can get a broader range of tones by swapping in photoresistors, which RadioShack sells in a 5-pack. Try different types of photoresisor, and also try removing one of the 0.22uF capacitors - this will alter the range of pitches you can produce. See and hear the Light Theremin in action here and here. Other Ideas and Projects You might want to have a go at some of the below instead, or investigate your own project. Check with me before buying too much! Vibrati Punk Console (£20 for kit) Luna Mod Looper The Bit Blob 2 & Bit Blob Jr. ($25-$150) Sound-Activated and Wearable Light Organ
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