Thyristor is a switching device based on internal regenerative feedback of 2 transistors. One of the most popular type is called silicon controlled rectifier(SCR). They are basically a PNPN structure. They are very reliable and have current ratings up to a few thousands amperes and voltage ratings up to 5000V. The power of this device is that it i
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s able to switch hundreds of watts of load by just supplying a few microwatts pulses onto the Gate of the device. This device can be turned on in about 1us and turn off in about 15us. This characteristic has enabled it to solve many industrial switching control applications where the switching can go up to a few kHz. It is turned on by making a gate positive with respect to the cathode. When the gate voltage reaches the threshold voltage and the current reaches the threshold current, the device will turn on and the load current will flow from anode to cathode. As shown in the figure above, the equivalent circuit of the thyristor consists of 2 transistors, 1 NPN and 1 PNP. By the structure, the Collector of PNP is connected to the base of NPN and hence a Gate is formed. Once the SCR gate is triggered ON, each transistor will hold the other one ON. The characteristic is shown in the figure below. The maximum reverse breakdown voltage must not be exceeded or else the device will be damaged beyond recovery. This device is a unilateral device in that it conduct in one direction only. Once it turned on, the internal resistance will drop to a low value and caused the device to go into saturation. In AC control circuitry, the device is in series with the load and a gate circuit is used to pulse the gate to turn it on. The turn off of the device is automatic when the AC line passes through zero. Load power is controlled by the...
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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