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Questions tagged [thyristor]

A three-terminal semiconductor device consisting of four layers of alternating type (N or P). The main terminals are the anode and cathode, connected to opposite ends of the four layers. The third terminal is called the gate, and a current trigger at the gate causes the device to conduct if it is forward biased.

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16 votes
3 answers
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Can a thyristor be built from two transistors?

Supposedly, an SCR/thyristor is just a simple, four layer PNPN semiconductor. If that's the case.. When a circuit calls for a SCR/thyristor, and there isn't one available, can it be substituted by (...
voices's user avatar
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7 votes
2 answers
3k views

Triac spurious triggering issue

I have a circuit where I am using triacs to switch home appliances like fan, tube light etc. This is the circuit I am using: (TRIAC1, TRIAC2, TRIAC3 come from arduino GPIO pins) First load is a fan ...
Whiskeyjack's user avatar
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1 vote
1 answer
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time delay circuit keeping line high

I'd like to create a simple circuit for keeping a line "high" for a few seconds after being triggered high, without any external power. To specify it in more detail: given three inputs, 3.3V, GND and ...
Nakedible's user avatar
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14 votes
1 answer
26k views

Optotriac+triac: how do I calculate the gate resistor

I am building a small circuit to turn on/off a 200W heater. I am using a MOC3023 and a BT136. At the datasheet of the the ...
Vorac's user avatar
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13 votes
7 answers
14k views

How to build a 2N6027 PUT?

Similar to this question, I need a replacement for a programmable unijunction transistor [PUT]. Specifically, I'm trying to emulate the behavior described in the 2N6028 datasheet. However, I would ...
glenneroo's user avatar
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7 votes
2 answers
2k views

Thyristor/SCR \$i^2t\$ and \$i^2\sqrt{t}\$ Rating

I have commonly seen the \$i^2t\$ rating for fusing in a SCR datasheet. This is a helpful rating for assessing if pulses which exceed the surge current rating (Itsm) of the SCR will damage it. ...
Oneneo's user avatar
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7 votes
6 answers
12k views

Replacement for 2N6027

I am working my way through Make: Electronics. For some experiments in this book, you need a 2N6027 programmable unijunction transistor (PUT). The shop I am buying my parts from doesn't have this ...
ubiyubix's user avatar
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6 votes
3 answers
916 views

what is a thyristor

As part of my 2330 lv3 am required to know about thyristors. I just want to confirm my understanding is correct. A thyristor is basically similar to a transistor, only it stays switched on when it's ...
Ageis's user avatar
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3 votes
3 answers
25k views

Average output voltage of a fully controlled full wave rectifier

What is the average voltage for a fully controlled bridge rectifier with firing angle \$\alpha\$ ? In a lot of web resources it is said to be: $$\frac{V_{max}}{\pi} (1+ cos(\alpha))$$ For example ...
Blue7's user avatar
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2 votes
3 answers
2k views

Does Thyristor (SCR ) works for Inrush current protection?

Does a SCR ie Thyristor work for Inrush current protection in a circuit ?
NSR's user avatar
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1 vote
2 answers
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SCR Gate to negative

Is a short circuit that occurs for as long as an instance safe? In the following schematic done from here, I have a silicon controlled rectifier that is used as a latch (the circuit simulation doesn'...
Bradman175's user avatar
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0 votes
6 answers
25k views

How to throttle power consumption of a heating coil?

Which is an appropriate but simple electrical circuit to reduce the energy (power) consumed by a heating coil which has an AC feeding without generating an asymmetric load (large DC component, e.g. ...
erik's user avatar
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0 votes
1 answer
120 views

Requesting clarity on the di/dt rating of thyristors

simulate this circuit – Schematic created using CircuitLab I have a general question about thyristors. I know that the di/dt limitation of thyristors is due to high currents flowing through ...
CaptainFantastic's user avatar
0 votes
1 answer
275 views

Zero Crossing Detector for Microcontroller

Im trying to design a control circuit for charge a battery, for this i will be controlling the battery charge by a 40tps ( SCR ), phase control. So my little understanding for what i read is that i ...
samuel mattio's user avatar