# 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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### Thyristor power factor problem [closed]

A thyristor half-wave controlled converter has a supply voltage of 240V at 50Hz and a load resistance of 100Ω. What is the overall power factor when the firing delay angle is 120°?
49 views

### Potential ground loop issue in DC-DC common ground circuit

I am trying to setup a dedicated battery for my dash-camera, this will provide continuous power when the ignition is OFF and has a manual NC switch to turn off the circuit when not needed. I ...
182 views

### How does this overcurrent circuit work?

Could someone explain how this short-circuit protection circuit works? As I understand it, Q4 and Q3 form an equivalent circuit of a thyristor, and it functions as a switch. When the thyristor ...
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119 views

### Conduction of Thyristor and Diode

Consider the following circuit: Let $\phi$ denote the angle for which the thyristor T1 is triggered, i want to know why when $\omega t = \theta \in (0, \phi)$ T2 and D2 are conducting i see ...
65 views

### Thyristor Choppers

I want to simulate this circuit to analyse its behavior: First I tried working the theoretic part of it: we suppose that the capacitor is charged initially thus $V_c = V_1 , i_l = -i_c = 0$ and ...
1 vote
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### Quantifying the reduction in a thyristor's turn-off time in response to increasing reverse voltage: Seeking data or graphs

From a previous question of mine (here: What factors affect a thyristor's "circuit commutated turn-off time"?), which was asked about 5 years ago, a user presented this very helpful ...
246 views

### How to interpret critical rate of rise of on-state current in a thyristor datasheet?

I'm looking at a number of thyristors (for example, this N2593MK160). Each has a critical rate of rise of on-state current. This limitation surprised me; I don't understand why the derivative of ...
489 views

### Thyristor blowing up in a coilgun

I am making a six-stage coilgun. I know the optocouplers are switched in the diagram, but the thyristors keep blowing up. They are blowing up randomly. That's my fourth thyristor I have replaced. ...
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### SCR phase control

I'm making a battery charger with phase control. While making the circuit I had some doubts. The transformer has a center tap, in this way I can make a full wave rectifier without diodes. Then ...
95 views

### Turn on control of antiparallel SCRs to pass AC

If you are trying to pass an AC signal through antiparallel SCRs (there to isolate the signal when required) where the AC frequency is low enough to satisfy the turn-off time requirements during the ...
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### Are Bridge AC to DC Rectifiers using thyristors still considered Linear Rectifiers considering their switching mechanism of action?

While I tried not to make the title confusing, Whether if the question is about Non-Linear/Linear PSUs or just the Rectifier circuits, I believe This one covers both matters. Considering that the ...
1 vote
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### Is my basic coil gun schematic correctly wired?

Recently, I came up with the idea of integrating a coil gun into a marble machine to accelerate an iron marble. I've done a fair bit of research into other people's projects, and ended up mixing what ...
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119 views

### Unable to fire thyristor simscape electrical matlab simulink

Hello, I am unable to fire a thyristor on simscape. I have tried to connect the gate to a pulse generator with a simulink-ps conversion symbol but it doesn't work ( the lines will not connect). I ...
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1 vote
278 views

### SCR gate drive options when optotriacs not suitable due to high voltage of 1600V

I am designing a 3-phase circuit to switch 1kV 50kW using thyristor pairs. The circuit is simple on/off switch, and needs to be simple as possible. I thought this precludes the use of pulse ...
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172 views

### Is it possible to make a halfbridge coilgun with high side IGBT and low side SCRs?

In a rather simple coilgun, the problem of freewheeling current from the coil is solved with a diode in parallel with the coil. The energy of the reverse current is wasted this way and even slows the ...
1k views

### Series thyristor circuit

I want to build a pulsed energy source and consider up to 6 kV for the storage capacitor voltage. The application is similar to a defibrillator but not for medical purposes. So any insights into what ...
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1 vote
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### How can I control a DC circuit via a high voltage AC signal?

I have a low voltage circuit of 9V DC supply voltage and a bunch of LEDs, and another circuit with 50V AC voltage. I want the DC circuit to work only if there is current flowing in the AC circuit. I ...
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1 vote
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### Thyristor T901N

The thyristor T901N in the Sinamics SL150 datasheet indicates constant operation limits based on temperature. In the datasheet, the continuous operation limits for this thyristor are as follows: ...
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### Can I use thyristor in place of pass transistor withvoltage regulator

I am making a circuit using an LR8 voltage regulator, and because the current may go over the recommended 10ma I will be putting a pass transistor to carry a little more current. The one I see most ...
59 views

### MOC3020X phototriac: Does minimum latch current affect other specs of the IC?

I use MOC3020 IC to control a thyristor for AC mains voltage. My project works as expected and I would like to make an improvement on the current consumption, as I saw that there are other MOC302X ICs ...
149 views

### Why is the SCR in this circuit switching off even though current is still above th holding current?

I am designing a circuit that controls DC power to a load through the use of SCR thyristors. I have been testing things out using the CLA20EF1200PZ part from Littelfuse. It has a 25 mA holding current ...
151 views

### Budget friendly battery charger controlled by phase angle ( SCR )

My circuit circuit is below so you can understand what I'm saying. I want to make a lead battery charger that can control the charging voltage and current (no discharge.) I have a circuit that ...
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### Is It Possible To Choose a Higher Holding Current When Designing SCR?

I'm looking at this data sheet: SCR data sheet on Digikey This device seems perfect for what I want to do, with 1 exception: The holding current is way too low. Various forums have suggested that (on ...
317 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 ...
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### For sufficiently low duty cycle, can you get away with driving SCR above rated current as long as A^2 * s are maintained?

I'm wondering if the A^2-s rating of an SCR is what ultimately decides whether a given current for a given time is okay, even if the data sheet does not list such a number. For instance, right now I ...
2k views

### SCR based rectifier vs IGBT based rectifier

I am wondering what is the difference in performance of rectifiers when used with SCR and IGBT. I searched on internet but all i can find is that IGBT is voltage triggered and SCR is current pulse ...
1 vote
482 views

### Thyristor gate triggering issue

We are using an MOC3041 to trigger the gate of a thyristor (BT155Z-1200TQ). We use the circuit design from the datasheet of the MOC3041 (Figure 12: Inverse−Parallel SCR Driver Circuit). We detect zero ...
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851 views

### How to make a driver circuit / trigger circuit /gate circuit for SCR?

Ii would like to ask you for help to understand the SCR, thanks in advance! I also hope this question helps another to understand this device too I have read about SCR in Boylestad book but it's ...
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### Three-Phase Thyristor Bridge Converter Simulation on Matlab

I am looking for a 24 pulse rectifier to power an electrolyser using a universal thyristor bridge from matlab. I am using a phase shifting zig zag transformer for this. The transformers are shifted by ...
1 vote
263 views

### What is Vac(peak) in this question?

Bit confused at what Vm/Vac(peak) is. Either 230V or 325V. rest seems simple
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### Can an SCR conduct backwards in large amounts while the gate is asserted?

I am driving an inductive load and have a situation where an SCR will be forward biased but conduct in reverse. Can it do that if I strobe the gate the entire time I want it to conduct in reverse? ...
1 vote
60 views

### Connecting the GND of an isolated circuit to the positive side of a 450V transformer output

I moved to a new company that makes very big old-style controlled rectifiers. They asked me to make a new modified, and enhanced thyristor-controlled rectifier. The strangest problem I faced is that ...
148 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 ...
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### Do commercial products exist for lab-scale thyristor triggering?

Hello fellow stack exchange members! We're excited about our novel high-voltage voltage-source-converter design that utilizes SCRs/thyristors and commutation circuits. We're now looking to build a ...
396 views

### Why does a MOSFET or IGBT's surge current rating stop increasing with decreasing pulse width beyond a point, unlike thyristors?

Thyristor The surge current rating of a thyristor increases as the width of the pulse decreases. For a single non-repetitive pulse, it's not uncommon for a thyristor to have a surge rating that is 10x ...
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### Help with this 3-phase thyristor triggering board

I need a triggering board which is able to drive thyristors such as (s8006l), and I found this board on Aliexpress which might be the hidden gem I am looking for. enter link description here enter ...
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### What is the most efficient circuit to control a 3-phase controlled rectifier circuit with the ability to control the firing angle?

I am trying to design a board to control a 3-phase full wave rectifier with the ability to control the firing angle (alpha) through a potentiometer or a selector, and I was wondering what are the most ...
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418 views

### Floating high-side thyristor switch is destroyed by massive gate voltage undershoots

I'm building a capacitor discharger with a thyristor for high-voltage impulse generation into an inductive load. To make the circuit easier to use, I wired the thyristor as a high-side switch. Then I ...
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954 views

### How does a TRIAC work?

I’m trying to understand the concept of a TRIAC. I’ve heard that a TRIAC is made with 2 SCRs (thyristors) connected in anti-parallel. But in the diagram I looked at, it looks like two SCRs were ...
344 views

### Calculating reactors for parallel connection of thyristors (SCRs)

I have been looking for more information on how to connect two thyristors in parallel in order to balance the load. From what I have found there are two options: either using balancing resistors, ...
163 views

### Difference between thyristor I(tsm) and I T(AV)

For example I have a capacitor send intermittent pulses to a coil send about 85A for few msec then off for 3-4 seconds (for 5mins) I was looking for a scr to switch it i found 40tps12 thyristor https:...
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364 views

### Connect two thyristor in parallel

I have 2 BTW69-1200 thyristor Vrrm = 1200 V Irms = 50 A I tsm (Non repetitive surge peak on-state current) = 610 (8.3 ms) - 580 (10 ms) Here is the datasheet https://pdf1.alldatasheet.com/datasheet-...
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130 views

### Thyristor external power supply

I am trying to make a kicker solenoid. My circuit is: 12 V battery connect to DC step up booster 300 V diode thyristor BTW69-1200 with external circuit (battery 1.5 V - resistor 1/4 W, 39 Ω) ...
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### Replace transistor-latch with thyristor: is my circuit correct?

Please consider the following two circuits: On the left, is a transistor-latch using a PNP and an NPN transistor. I'd like to replace those two transistors with a thyristor, mainly to get a little ...
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### Why is my SCR controlled by a photodiode pulsing when supplied with high voltage

I am working on a circuit which when a photogate (consisting of a photodiode and a corresponding LED) is interrupted, an SCR is triggered which discharges a capacitor through a solenoid. I built and ...
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### Basic thyristor questions TYN1225

I have the component TYN1225 that I believe to be a thyristor. I just read about thyristors that are described as rectifiers enabled or non enabled on demand. According to what I read and understood ...
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### Why do NPNP thyristors remain on but NPN transistors don't after gate voltage is removed?

My understanding is that when a positive voltage is applied to the gate in a thyristor, the P region can store excess electrons which can then move to the n region. I don't understand why it continues ...
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### Thyristor holding current Vs VD (turn off voltage)

I am working on a LC discharge which use a thyristor when the C capacitor voltage exeed a reference voltage. The capacitor is charged by a flyback converter. The flyback converter is stopped during ...
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