;D Hello!!
this is my first post here so please be gentle!
i am trying to use an antenna with my arduino, much in the same way one is used with a theremin, and all i basically need is some sort of readout/number that is affect by the distance your hand is from the antenna, which i can then configure and use through max msp as a starting point.
any help would be fantastic with this as i'm at a total loss
i thank you in advance
regards
Andrew
Hi
Arduino has two kinds of inputs
Digital that will read 0 V or 5V - used for "sensing" switches or turning stuff on / off
Analog that will read a voltage between 0V and 5V and convert it to a number in the 0 - 1023 range.
You would need some kind of device that would convert proximity to the antenna to a voltage between 0 and 5 volts and connect it to an analog input. How to do that i don't know. I know that there are some capacitive sensing IC's but maybe they only work if you actually touch them.
Hope this is a little push in the right direction.
MikMo
thank you very much, any help at all is well recieved
hey
just google up a theremin schematic, and find the point in the schematic that has a decent voltage range, something like 0-5V.
Alternately you can use the analog inputs as a sort of theremin, but they will jump all over the place in an unreliable way. Just conect a 12" wire to one of the inputs.
D
so it looks like the best bet is to use the arduino as a sort configured meter reading the voltaeg accross the antenna, an just have to out put a sound rather than a value
its just setting up the antenna thats the tricky bit
hello,
as daniel pointed out, simply hooking an antenna-wire or plate is not very reliable. it will let you measure some micro induction, which is way too sensitive for an instrument. (correct me if i'm wrong, but i think that this is not the way the original theremin works)
some weeks ago i tinkered with a 555-Timer-IC to get an theremin-like interface to control a frequency. look for a "555 metronome circuit", which is an astable multivibrator circuit, meaning that it will output a fixed frequency depending on resistor and capacitor values. the frequeny depends on how long it takes to charge and discharge the capacitor using the given resistors. knowing that, i replaced the capacitor with 10x10cm aluminum (not very sure about the metal) plate and got mixed results. i was able to control the frequency quite reliably by moving my hand closer to the plate, but only in a very unpracticle 3 cm range. i experimented a little with the resistor values but gave up very soon. i think the principle works, but i got unsure whether 5V were enough at all for this concept to make a sensor that works precisely over a let's say 1m range. it wasn't my knowledge on electronics that let me think so, but rather noticing that all smaller (homemade, battery-powered) theremins have a quite small range of operation.
the minimum theremin:
a theremin is just an unstable oscillator... with no one near it, it oscillates at X frequency. When you wave your hand near it, the frequency changes by say 1KHz, and this change is mathematically derived.
D
This is what i would do : Get a good theremin circuit (a tunned one with a nice movement amplitude) and use a frequency detector ( fft ? ) to read the value.
very interesting project. Im new on Arduino and phisical computing but i really believe the theremin interface could really amaze people if related to visual stimulation a changes in the enviroment.
Cheers,
DrFuinha
A theremin is not just an unstable oscillator. It consists of two oscillators running at very high frequencies, the tone you hear is the beat frequency that comes from detuning the two oscillators a little bit. The antenna is copuled to one of the oscillators and changes its frequency and this creates the beat frequencies.
A simple theremin like circuit can be made from a 555 based oscillator and a light dependent resistor. With this circiut you can not change the volume as you can with a real theremin, only the frequency.
MikMo
http://ww.mikmo.dk