Electronic equipment is not `cheap` and can be damaged in a number of ways, by electro-static discharge, by lightning and by transmitting withno antenna attached, or into an antenna with a high SWR. The controller described herein attempts to facilitate the safe and automatic tuning of a mag loop antenna by reducing the output power to an acceptable level via ALC control so the RF output
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circuitry will not be damaged when the line SWR is high For several years now I have been experimenting with Magnetic Loop Antennasat this QTH. In the beginning, I tried octagonal 3/4" copper loops with homebrew trombone` capacitors wrapped in Teflon tape and driven by a surplus screwdriver motor. While they worked OK, they were a real nuisance to peak after QSY`ing. After this, I built a similar loop that used an MFJ butterfly capacitor, driven by the very same motor that MFJ uses in their magloops. The motor was controlled by a microprocessor and an SWR bridge designed to automatically sense resonance. This semi-automated approach worked better, but experienced difficulty hitting the sweet spot` as the analog motor controlled by a M/P generated PWM signal would often drift past resonance, and the controller would keep hunting back and forth over it. Operation was not always consistent. Finally, at the suggestion of Byron WA8LCZ I used a stepper motor in conjunction with the MFJ butterfly capacitor and programmed the controller to automatically hunt for resonance. The microprocessor driven controller when activated will perform the following steps: If desired, the capacitor can be rotated manually, at either slow or fast speed. Resonance will be noted by themarked increase in background noise. The current design works best with butterfly capacitors as it`s very difficult for the controller to determine in which direction...
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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