Electronic Component Kit for Starters and Beginners from ProTechTrader

jojo June 14, 2016 1 Comment

Are you a beginner in Electronics wondering where to start? Well, we’ve all been there once like you, swimming on the shores not knowing where to go and wondering, “What’s the difference between resistance and capacitance?” or “Who is Georg Simon Ohm and why does he have a law?”   In this article, we are reviewing an awesome electronic component kit from ProTechTrader, which caters to all beginners and enthusiast looking to get started in the exciting arena that learning...
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Characteristics of a UJT

jojo September 17, 2009 5 Comments

UJT Characteristics The static emitter char­acteristic (a curve showing the relation between emitter voltage VE and emitter current IE) of a UJT at a given inter base voltage VBB is shown in figure.  From figure it is noted that for emitter potentials to the left of peak point, emitter current IE never exceeds IEo . The current IEo corresponds very closely to the reverse leakage current ICo of the conventional BJT. This region, as shown in the figure, is...
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UJT-Uni Junction Transistors

jojo July 21, 2018 26 Comments

In this article, we learn about UJT (Uni Junction Transistor) in detail. We cover a lot about UJT like – what is basically a UJT, how they differ from other transistor models, how to construct a UJT, operation & working of a UJT, how to build applications of UJT and so much more. Lets dive into details of Uni Junction Transistors. Unijunction transistor (abbreviated as UJT), also called the double-base diode is a 2-layer, 3-terminal solid-state (silicon) switching device....
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LASCR-Light Activated SCR

jojo September 17, 2009 2 Comments

Light activated SCR (LASCR) or a Photo SCR  is just an ordinary SCR except that it can also be light triggered. Most LASCRs also have a gate terminal for being triggered by an elec­trical pulse just as a conventional SCR. The basic construction of an LASCR is shown in figure. The schematic symbols most commonly used for the LASCR are shown in figure.  Some LASCRs have clear windows in their cases so that light sources from other devices can...
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Gate Turn Off Switch

jojo September 18, 2009 1 Comment

Gate turn-off switch (GTO) is, like an SCR, is a four layer, three junction semiconductor device with three external terminals, namely, the anode, the cathode and the gate, as illustrated in figure. The basic construction, schematic symbol of a GTO are shown is figures  respectively.  Although the graphic symbol is different from either the SCR or the SCS, the transistor equivalent is exactly the same and the characteristics are similar. The main advantage of the GTO over the SCR...
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Silicon Unilateral Switch

jojo September 16, 2009 3 Comments

The diac and the silicon bilateral switch are grouped as bilateral or bidirectional devices because they can breakover in either direction. There are also breakover devices which breakover in only one direction; they fall in the category of unilateral or unidirectional breakover devices. Although unilateral breakover devices are more frequently employed in SCR triggering, they can also be employed in triac triggering circuit if they have some extra supporting circuitry. Silicon unilateral switch (SUS) is one of the important...
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Silicon Bilateral Switch

jojo September 16, 2009 2 Comments

Silicon bilateral switch (SBS) is another breakover device which is capable of triggering triacs, and it is popular in low-voltage trigger control circuits. They have breakover voltages lower than those for diacs, ± 8 V being the most popular rating. V-I characteristic curve of an SBS is similar to that of the diac, but it has more pronounced “negative resistance” region i.e., its decline in voltage is more drastic after it enters the conducting state. The schematic symbol and...
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Shockley Diode

jojo October 2, 2013 9 Comments

To know more on the invention and history of the device click on this link - Shockley Diode – Invention History The four-layer diode, also called the Shockley diode after its inventor William Shockley, is essentially a low-current SCR without a gate. It is classified as a diode because it has only two external terminals through anode and cathode. Because of its four doped regions it is often called a P-N-P-N diode. The basic structure, two transistor version, equivalent tran­sistor...
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SCS-Silicon Controlled Switch

jojo September 16, 2009 2 Comments

Silicon controlled switch (SCS), like the SCR, is a unilateral, four layer three junction P-N-P-N silicon device with four electrodes namely cathode C, cathode gate Gx, anode gate G2 and the anode A, as shown in figure. Infact, the SCS is a low power device compared with the SCR. It handles currents in milli amperes rather than amperes. SCS differs from an SCR in the following aspects. It has an additional gate—the anode gate.It is physically smaller than SCR.It...
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GCS-Gate Controlled Switch

jojo September 16, 2009 1 Comment

As mentioned earlier, low-current drop out is the normal way in which the SCR is turned off. Gate-controlled switch is designed for easy opening with a reverse-biased trigger. A gate controlled switch (GCS) is closed by a positive trigger and opened by a negative trigger (or by low-current drop out). Gate-controlled switch circuit is shown in figure. Each positive trigger closes the GCS, and each negative trigger opens it. Thus a square-wave output is obtained, as shown in the...
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