This is an application of what`s known as `random fire` technique for full phase control. The term random iskind ofmisleading. Dimming cannot be effected bytriggering the gateindiscriminately;triggering (firing)must be done synchronised with the line frequency. The line frequency is detected by finding the zero-cross, the point where the line volt
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age is at or near zero, which occurs with each alternation (half-cycle). The Arduino gets zero-crossing pulses from U1`s output at one of its hardware interrupt pins (D2). The delay angle is selectable via two DIP switches. The default is 1 msec and the DIPs add in binary [i. e. delay time = 1msec + 1, 2, or 3 msec more. ] With that, the conduction angle can be set to 158, 135, 112, or 90 degrees [approx. ]. Obviously, more resolution could be had with more switches, and there`s no obstacle as such in doing so, it`s academic enough, but my objective was not somehigh degree of (or seemingly continuous) variability. This is a research project and thesefew well-definedoptions are sufficient. The zero-cross signal is awaited, its occurrence initiates the Interrupt whereupon the DIPs are read and thereby the delay time determined, then shortly the Gate signal pulses after the appropriate delay time and the process repeats. As there`s a snubber across the TRIAC and a snubber for the gate, too, I do intend to try it all outwith a fan. That`s my plan. But I confess that I`m squishy on it right now - preferring to bask in the glow of my present success before plunging into a power factor situation. I have been using "TRIAC", my preference. Should I use Triac when it`s the first word of a sentence and triac otherwise A textbook of mine, "Industrial Solid-State Electronics", uses the latter word form. 26 NOV 2012 The results with a...
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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