Hello all,
I have been playing with robotics for a while. About a year ago I came across some DIY capacitive sensors. In particular I came across a digital Theremin circuit, which offered omnidirectional proximity sensing. Then a little while ago, someone else posted here about theremins, getting me thinking about this all over again.
I wanted to use the digital theremin circuits to make a cheap proximity sensor, but I want it to be highly directional.
My basic understanding of the circuit is that you create a frequency of pulses. On a parallel circuit you interface an antenna to a similar circuit running at the same frequency. The output is the difference between the frequencies. So if you used R/C to build your frequency networks, the capacitance of the antenna will have an affect on the frequency output from that leg, and an object that is close enough begins to affect the capacitance of the antenna. Supposedly this can measure the capacitive different down to the pF's.
All models of a theremin I have seen use an omni-directional antenna. Why don't they use an array, yaggi, or rhombic?
I guess my main question is: Does the directional electromagnetic sensitivity of an antenna array have the shape and/or pattern as it's directional capacitive sensitivity (or does it even HAVE a directional capacitive sensitivity)?
Thank you all very much, sorry for the weird question. This has been bugging me for a while.
I have been playing with robotics for a while. About a year ago I came across some DIY capacitive sensors. In particular I came across a digital Theremin circuit, which offered omnidirectional proximity sensing. Then a little while ago, someone else posted here about theremins, getting me thinking about this all over again.
I wanted to use the digital theremin circuits to make a cheap proximity sensor, but I want it to be highly directional.
My basic understanding of the circuit is that you create a frequency of pulses. On a parallel circuit you interface an antenna to a similar circuit running at the same frequency. The output is the difference between the frequencies. So if you used R/C to build your frequency networks, the capacitance of the antenna will have an affect on the frequency output from that leg, and an object that is close enough begins to affect the capacitance of the antenna. Supposedly this can measure the capacitive different down to the pF's.
All models of a theremin I have seen use an omni-directional antenna. Why don't they use an array, yaggi, or rhombic?
I guess my main question is: Does the directional electromagnetic sensitivity of an antenna array have the shape and/or pattern as it's directional capacitive sensitivity (or does it even HAVE a directional capacitive sensitivity)?
Thank you all very much, sorry for the weird question. This has been bugging me for a while.