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2answers
45 views

SCR “current gain” - calculating gate resistance

Trying to understand the SCR. Have made this outlay which I shall find the right resistors for. The SCR is a TYN1225 But since I have found it difficult to understand \$I_{GT}\$ and \$V_{GT}\$ I ...
0
votes
1answer
28 views

AC circuit to act as a relay for another DC circuit

In this circuit, I have caused an AC current to power the gate pin of the Thyristor, which in turn should allow the 10v DC current to pass even after the AC current inverses - it is not a ...
3
votes
1answer
36 views

Why does a triac trigger with gate current in either direction?

I've been coming up to speed on thyristors, and triacs in particular. I've found detailed material on them a little hard to find, in particular on the device physics. Horowitz & Hill is silent on ...
2
votes
1answer
229 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 ...
1
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0answers
46 views

thyrsitor leakage

I have built a circuit to switch a thyristor* on and off . The circuit is like the circuit below. when the gate is on all is right and the device is latched when the gate voltage is removed , but ...
0
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1answer
274 views

Thyristor gate resistor calculation

I am working on a thyristor (in my case: Semikron SKKT 253/08) circuit operating at 400 V mains (3 phase). What I'm wondering is how one can calculate a thyristor gate resistor so 12 VDC applied at ...
-1
votes
1answer
87 views

Design of three phase thyristor circuit for temperature controller

Circuit is powered by 3 phase, 415 V AC. This is connected to nri halogen tubes to heat a chamber up to 20 kW and 700℃. I have to control temp using delta controller DTA 7272 which will sense ...
0
votes
1answer
50 views

Resistance firing circuit of thyristor

can someone explain the following conditions shown in the image: why condition 1 and condition 2 are there? In condition 1 they have taken the current as Vm/R1 while in the 2nd condition curren is ...
1
vote
2answers
79 views

Negative gate pulse to a thyristor

If a positive gate pulse is given to a forward biased thyristor, it gets turned on. What will happen when a negative gate pulse is given to a reverse biased thyristor ?
2
votes
1answer
48 views

How to isolate a zero-cross detector from phase-controlled simistor?

To control the average voltage, output by a triac, the controller needs to know the time of the zero crossing. But the circuit for detecting the zero-crossing is a sensor, vulnerable to noise; taking ...
0
votes
1answer
69 views

Why do we need zero voltage reference circuit for micro-controller?

I am designing a circuit for controlling triac firing angle. For controlling purpose i'll be needing a micro-controller. Now the confusion is why do i need zero voltage reference circuit for ...
0
votes
1answer
462 views

IGBT vs. SCR rectifier

I simulated three phase rectifier using a thyristor like so: I get the expected result. But if I change the thyristors to IGBTs as shown below, it does not work. Why do these two circuits behave ...
1
vote
1answer
37 views

Low on state voltage clamp

I have an +- 10V/1A sawtooth signal that needs to be clamped to gnd when a trigger pulse is received. The signal is supposed to stay clamped until the next zero crossing, upon which the circuit is ...
0
votes
1answer
45 views

Gate controlled turn-on time

Under DYNAMIC CHARACTERISTICS for BT137 is Tgt value set to typically 2us. If I then look under BTA16, I see no mention of the pulse width. Is there a minimum pulse width as a standard value for all ...
0
votes
2answers
1k views

Thyristor voltage regulator with different fireing angle for each period with simulink

First of all I'm really low with EE so please, go easy on me. As home assigment we have to design Thyristor voltage regulator in simulink. It should run for 5 periods with different thyristor fireing ...
1
vote
1answer
101 views

Thyristor not switching on when 'cold'

I have breadboarded a simple circuit using a 2N6395 thyristor to drive a resistive load. In simulation all works well, and even the physical implementation works sometimes. simulate this ...
0
votes
1answer
214 views

How do I convert 50Hz AC to 60Hz AC using a cyclo-converter?

I want to design a 3 phase cyclo-converter to run a 7.5kW induction motor. The input to the cyclo-converter is 50Hz AC and the output of the cyclo-converter should be 60Hz AC. What are the specific ...
3
votes
2answers
452 views

My half wave rectifier graphic is wrong

Here is the circuit we used (BT169 thyristor): And this is the output: In theory it should be a straight line when AC source goes negative. The question is "Why does it go into the negative ...
1
vote
2answers
69 views

High frequency use of thyristors

Can I use an SCR such as BT151 or BT136 (or even a triac such as TYN616), to pass a high voltage(400V) high frequency signal (pulsed DC at 50KHz) for a fixed period? such as 1 second on, then off for ...
0
votes
1answer
314 views

Low Breakover Voltage Diac [closed]

I wanted to know if there is commercially available Diacs with Breakover Voltage of 20V or less. I tried to find in the internet but always ending up to Diacs with Breakover Voltage of around 30V or ...
0
votes
1answer
275 views

How can I convert very high, fluctuating, AC voltage to 240VAC at 50Hz?

I'm about to finish a generator-alternator setup which will generate 9-phase AC electricity at (as yet unknown) very high voltage, most likely around 4800V. I'm not sure what the frequency will be, as ...
1
vote
2answers
295 views

What are the two gate leads on a thyristor?

I have a simple question: what is the second gate lead on a power thyristor (see the figure below) ? What is it physically attached to ? I understood that the thyristor turns on when you force a ...
1
vote
2answers
299 views

Why are thyristor stacks hung from the ceiling?

The Wikipedia article on thyristors as well as the one on valve halls mentions that thyristor stacks in HVDC applications can be hung from the ceiling or supported by insulators mounted on the floor. ...
1
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0answers
660 views

What is a Thyristor Switched Series Capacitor (TSSC)?

I'm struggling to understand the physical difference between the Thyristor Switched Series Capacitor (TSSC) and the Thyristor Controlled Series Capacitor (TCSC). From this book, I understand that a ...
0
votes
1answer
179 views

High power power regulators - thyristor regulator?

I am currently working on a system design that intends to control heating in different zones. All zones in total is calculated to use approx 340kW (230V). This will be divided into 11-12 smaller ...
0
votes
1answer
790 views

Three-Phase Thyristor Converter Simulation Question

I am required to simulate a three-phase full wave thyristor converter using MATLAB Simulink. The circuit I have so far is given below: The three input sources are 230V each at 50Hz, the first ...
0
votes
7answers
3k 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. ...
0
votes
1answer
199 views

Controlling AC devices using ATmega8

I have an microcontroller ATmega8, TRIAC MOC3083 and thyristor M166P. I need to develop and device which will turn on/off lamp(220V). But while I'm developing I don't want work with AC 220V now, DC ...
2
votes
2answers
4k 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 ...
3
votes
2answers
343 views

Why doesn't the leakage currents automatically turn on thyristor?

I understand that when \$TR_1\$ and \$TR_2\$ are ideal transistors, we need an initial \$I_G\$ current pulse signal in \$G\$ to turn on the thyristor. This \$I_G\$ will turn on \$TR_2\$ and the ...
9
votes
1answer
8k 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 optotriac, this circuit is recommended: My question is how is the 180Ohm ...
1
vote
1answer
580 views

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 ...
0
votes
3answers
614 views

Turning ON a Thyristor

Well, I've recently started reading about thyristors and I have been stuck by something my instructor said about the turn-on process. During the forward-biased state of the thyristor the junctions ...
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7answers
7k 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 ...
8
votes
1answer
778 views

Thyratrons: How they work, what they are used for, and how to read their datasheets

I recently ran into an interesting device called a thyratron. I have a basic understanding of thyratrons as gas filled vacuum tubes. I understand that they can switch large amounts of currents and ...
5
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3answers
393 views

Switching-on/off 1000V * 1000A in 10ns

I know that kind of things could be done by thyratrons, but wikipedia says that they are being phased out by semiconductor devices. Could anyone suggest which kind of devices can switch on that fast ...
4
votes
3answers
555 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 ...
5
votes
6answers
5k 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 ...