How to use Pyroelectric ("Passive") Infrared Sensors (PIR) Father AI Sensor Array - LVL1. Description: This is the sensor array for the Father AI project. This makes Father AI aware of its environment. More Details: Photo Gallery: This post was submitted by admin. Helmholtz resonance. A brass, spherical Helmholtz resonator based on his original design, circa 1890-1900. Qualitative explanation[edit] When air is forced into a cavity, the pressure inside increases. When the external force pushing the air into the cavity is removed, the higher-pressure air inside will flow out. The cavity will be left at a pressure slightly lower than the outside, causing air to be drawn back in. The air in the port (the neck of the chamber) has mass. Quantitative explanation[edit] It can be shown[2] that the resonant angular frequency is given by: (rad/s), where: (gamma) is the adiabatic index or ratio of specific heats.
For cylindrical or rectangular necks, we have is the equivalent length of the neck with end correction, which can be calculated as :, where is the actual length of the neck and is the hydraulic diameter of the neck[3]; is the volume of air in the neck, thus: From the definition of mass density ( , thus: and fH is the resonant frequency (Hz). Applications[edit] Notes[edit] PCL - Point Cloud Library. DIY Bend Sensor (Using only Conductive Bags and Masking Tape)
So, after lurking around in the shadows for years I've finally gotten round to making my first step-by-step instructable. *yay* A little background as to how this whole idea came about. Back in 2009, I needed some bend sensors for a sign language translation glove I was making for fun, and the commercial ones that just came out were over my budget considering I needed at least 10. Then I came across plusea's DIY bend sensors on Instructables. It was what I was looking for but I had one small problem. Well, a few problems actually. So I decided to see if I could just experiment with the conductive anti static bag(although in all honesty I tried matching it with a whole bunch of other stuff; like carbon paper). So for all of you who has a tight budget or like me, can't get easy access to items in the states, this is for you.