This page describes the construction of an electric field mill. This is a device to measure the electric field strength on earth due to the static electric field and the charge of clouds passing overhead. It can also be used to investigate static electricity effects. The body and chopper of the field mill are fabricated from a 4 inch diameter duct
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fan. The signal conditioning electronics uses a chopper blade position detector and a synchronous detector to reduce noise and recover the field sign (positive or negative) as well as magnitude (strength in V/m). 1. Martin A. Uman - Lightning, McGraw-Hill Book Company, New York (1969), 264 pages. Russian translation (1972), revised edition, Dover, New York (1984). (Available at Borders) The strength of the electric field could be measured, in principle, by placing a volt meter across plates placed some distance apart. However, because the meter will have some input impedance (10 Meg typically), any voltage induced on the plates will quickly drain away, and would not be useful for measuring the static field. To make measurements of the static field, the chopper technique is used. The chopper blade is arranged over the Sense Plate and rotated so that it periodically shields, and exposes the Sense Plate to the electric field. To properly do this, the Rotor must be grounded. The Sense Plate is grounded through a transconductance amplifier, which converts the Sense Plate`s ground current to a voltage. As the Sense Plate is exposed to the Field, the field induces ground currents as it attracts or repels charge from the Sense Plate. As the plate is shielded from the field, the induced charge drains away. So the chopper induces an AC ground current which is proportional to electric field strength. This AC signal could then be...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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