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Astatic model D-104 microphone. In 1930, two amateur radio operators, Creed M. Chorpening, W8WR (later W8MJM) and F.H. Woodworth, W8AHW began experimenting with different types of microphones for their "ham" stations. Their mutual friend, Charles Semple, worked for Brush Development Company where he had been experimenting with Rochelle salt ...
The charged elements in the vacuum tubes can mechanically vibrate, changing the distance between the elements, producing charge flows in and out of the tube in a manner identical to a capacitor microphone. A system sufficiently susceptible to microphonics could experience audio feedback, and make noises if jarred or bumped.
The dynamic microphone (also known as the moving-coil microphone) works via electromagnetic induction. They are robust, relatively inexpensive and resistant to moisture. They are robust, relatively inexpensive and resistant to moisture.
The first static induction thyristor was invented by Japanese engineer Jun-ichi Nishizawa in 1975. [5] It was capable of conducting large currents with a low forward bias and had a small turn-off time. It had a self controlled gate turn-off thyristor that was commercially available through Tokyo Electric Co. (now Toyo Engineering Corporation ...
An electret film is applied to the back plate of the microphone capsule and the diaphragm is made of an uncharged material, which may be mechanically more suitable for the transducer design being realized. Front electret This design features no back plate, and the capacitor is formed by the diaphragm and the inside surface of the capsule.
As a static force, it does not create vibrations nor acoustic noise. However torque ripple (also called cogging torque for permanent magnet synchronous machines in open circuit), which represents the harmonic variations of electromagnetic torque, is a dynamic force creating torsional vibrations of both rotor and stator.
In some cases, these terms are more precise, as there are various types and causes of echo with unique characteristics, including acoustic echo (sounds from a loudspeaker being reflected and recorded by a microphone, which can vary substantially over time) and line echo (electrical impulses caused by, e.g., coupling between the sending and ...
Gold-leaf electroscope, showing induction (labelled polarity of charges), before the terminal is grounded. Using an electroscope to show electrostatic induction. The device has leaves/needle that become charged when introducing a charged rod to it. The leaves bend the leave/needle, and the stronger the static introduced, the more bending occurs.