2.12. How can I do a simple, inexpensive active control demo?
Description
This article is from the Active Noise Control FAQ, by Dr. Chris Ruckman
2.12. How can I do a simple, inexpensive active control demo?
Because active control employs some interesting physics, readers often ask how to construct a simple, low-cost demonstration as a student project or for instructional purposes. Here are three possibilities:
First, the hard way: it is possible to construct an analog feedback controller using op-amps, capacitors, speakers, and other parts available from any electronics supplier. While simple in concept, constructing such a demonstration requires a pretty solid foundation in acoustics, electronics, and control theory, and is well beyond the scope of this FAQ. [Please DO NOT ask the author for instructions. CR]
A second approach is much more powerful and flexible, but only if you have a budget on the order of US$2000 or so: the EZ-ANC from Causal Systems. This comprehensive kit includes hardware, software, and a complete theoretical/user's manual. (See Section 3.2 for contact information, or check out their web page: http://www.io.org/~causal/cs/csdir01.htm)
A third alternative is much less expensive, but not as flexible: the "ANR Adapter" from Headsets, Inc. The ANR Adapter is an add-on kit that transforms an ordinary passive pilot's headset into an active noise control headset. The kit costs only US$100; you supply the headset. The makers claim roughly 22 dB attenuation from 20 Hz to 700 Hz. If you simply want a demonstration in which you flip a power switch to hear active noise control at work, this kit may be for you. (See Section 3.2 for contact information. For a review of the product, see the following magazine article: Picou, Gary, "Low-Rent ANC," The Aviation Consumer, vol.25, No.7, MAY 01 1995, p.10-12.)
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