Questions tagged [scr]

A Silicon Controlled Rectifier - A PNPN or NPNP semiconductor device that once triggered stays in permanently conductive state until the current is removed. USed in protective circuits and chopper style light dimmer switches. Also know as a thyristor.

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Why are thyristors used in xenon trigger coil circuits?

Looking at the datasheet for the ZS1031-11(H) trigger coil, the test setup activates the trigger coil with a thyristor: In the datasheets for other trigger coils, and in other circuit diagrams online,...
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33 views

Datasheet/pinout for S116T (1A 400V SCR)

In my inventory, I found a component labeled S116T. I bought it a long time ago from a shop which describes it as "THYR 1A 400V". So the device is an SCR, but I can't find any datasheet for ...
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35 views

Problem with SCR latching circuit

I put this circuit together to demonstrate latching properties of SCRs but I'm finding that the SCR doesn't behave as I expected it to from the datasheet values. Specifically, I found that in the ...
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39 views

Simple security Alarm incorrect schematic diagram

I am a student and my Applied Physics teacher gave an assignment to create a schematic diagram of a security alarm. The main Components are, Switch (Simple on/off) SCR C106B (Silicon Controlled ...
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32 views

Is there a one trigger latch for AC?

SCR is good for latching DC source, one trigger will turn on the source indefinitely. But how about AC source? Latching mechanical relays is good but it is too big for me. Triac is designed for AC ...
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24 views

Is there a protection needed in the mcu connected to SCR?

When an SCR is connected to high voltages (220Vrms) while it's gate is being controlled by pulses using a microcontroller powered by only 3V, is there a protection needed in the microcontroller? My ...
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63 views

SCR surge voltage rating

A question on SCR/thyristor voltage rating: For SCR rated at 100A 400V. i.e. It seems common the rated current can take 10x more surge current so 1000A surge for 100A SCR without damage. Can also ...
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42 views

High power heating element control

How to control high power (~5kW) heating element using MCU? I need a very simple application that shuts down the element, when it reaches set temperature. Maybe I can do it using SCR? F.e. Т161-160 (...
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50 views

Snubber circuit to protect SCR/Diode

In my circuit I need to discharge a capacitor into an inductive load using SCR. In order to make the circuit oscillate there'll be a diode antiparallel with the SCR, as you can see in the picture. My ...
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44 views

interfacing MOC3021 with high current back to back scr

I want to drive two back to back thyristor with moc3021 for soft starter.Here is the circuit: This circuit works for medium power SCR such as BT152,But I want to drive a couple of disk thyristor that ...
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25 views

back to back SCR firing circuit

I am trying to design a 3-phase soft start circuit.Are these two circuits different? My PCB design and RC snubber between anode & cathode is based on the second one.I want to make sure my circuit ...
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63 views

Triacs are getting damaged BTA41 BTA24

guys, I tried to make an SSR for my window Air conditioner 2 Tonnes "2.5kW" the problem the Triacs get damaged instantly I tried 4 Triacs so far 2 BTA41 and 2 BTA24 I tried different circuits, I'm ...
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72 views

Why crowbar is needed?

I know it is to protect sensitive load, but doesn't the zener diode in the power supply already do that? zener diode inside the power supply already limits the voltage to its breakdown voltage. Why do ...
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102 views

Can I use any digital component to avoid 7805 killing my microcontroller directly when its ground is disconnected (hence 12v goes to uC directly)?

My idea is to have an intermediate cheap component that will blow-up before my uC if the voltage goes above 5v from 7805 (or even some fuse, but I am not sure if a fuse will blow-up with over-voltage ...
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162 views

TL431 crowbar simulation problem

I'm trying to simulate crowbar circuits, which is mentioned on page 8 of ON SEMI TL431 datasheet (https://www.onsemi.com/pub/Collateral/TL431-D.PDF). I'm using TINA TI for this. There are two circuits,...
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48 views

What happens when we discharge a capacitor through a SCR which we leave open?

I am wondering what would happen when we discharge a capacitor, by using a SCR, through a coil and we leave a current applied to the gate of the SCR. The coil should generate a ‘reverse’ current right?...
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Open load detection using SCR

I have a load I control via back to back SCR during zero crossing circuit. The load is powered via 208Vac and pulls about 15A. I have an EMI filter using safety caps at the output. I need to detect ...
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2k views

Why in the world would the tab on a TO-220 package have a connection to anything (but GND, if applicable)?

I know this is in some way a different version of the prior question In i.e. a TO-220 package, why is mounting the (pin connected) tab to case safe? But I am not looking for ideas what to do to mount ...
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102 views

Debugging a battery charger circuit

I have built a circuit of a battery charger here. Here is the circuit in the original project: However, it doesn't seem to work. The output I measure at the battery charging clips is only 1.2 V or so ...
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287 views

How DIAC works?

I edited my whole post for more refreshed information I learned about DIAC. Let's consider the following circuit and how it works. First of all the Vs must be higher than break voltage of diac, so ...
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70 views

SCR for load bank switching?

I'm building a load bank for testing high power lead acid batteries, and expect to pass up to 800 amps at 12 VDC. I could do it with contactors but would like to use an SCR with a pot and allow the ...
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768 views

How to install a scr model in ltspice

I have downloaded an scr model file from this website and pasted it in the same folder as that of my .asc file. But ltspice still shows unknown subcircuit called for the scr present. What am I doing ...
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126 views

Arduino died when grounds got disconnected

Alright bear with me since English is not my first language and it's my first time posting here. So I was using my Arduino Nano (not genuine) to drive a single phase full bridge rectifier. The ...
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54 views

Turn on Mosfet by SCR

can the Mosfet be turned on as shown on picture? My desire is voltage on M1 fire the SCR stay on forever. V2 is ramp voltage.
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34 views

Is zero loss turn-off possible for thyristors?

Consider this very basic circuit: simulate this circuit – Schematic created using CircuitLab Don't mind the values - they don't matter, as this question is conceptual. Imagine that Vcomm is ...
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35 views

SCR reverse current during switch off

In the figure below is shown the dynamic behavior of an SCR in terms of its current during switch off. I'm interested in calculating the maximum reverse current (iR in the plot). The parameters that ...
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47 views

Question regarding the trigger circuit for an SCR-based coilgun

I'm an EE student, trying to design a coilgun project. I have had luck with a basic prototype similar in construction to the one on this site, however with smaller flash capacitors in parallel (total ...
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145 views

How to reduce spike in Power Supply and GND (SCR + Ignition Coil)

My circuit: Signal coupled in power supply (3.3V) of STM32F103 during spark: Is there any benefit to using this diode (circled in red) or not (without this diode the snubber circuit will start ...
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3answers
256 views

Crowbar Circuit Resistor

I have a crowbar circuit which uses an SCR with 100mA gate current shown below. In order to use this resistor value at 100mA it would need to be rated for 60W. Obviously here the resistor will pop. ...
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189 views

What can I use to turn on a circuit at 5V?

I'd like to power an Arduino using a supercapacitor. I already have that part of the circuit figured out. But I want to charge the supercapacitor using an external power source, without the ...
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51 views

Why on shutdown the SCR can be compared to a power diode?

I have this as a homework question and can't seem to find the answer in my notes, book or internet. I know they will behave similarly when there is a reverse polarity on both, but the way my professor ...
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293 views

Xenon Flash thyristor trigger

I'm building a xenon flash unit with a power of 50Ws (300V 1000uF capacitor). I need to trigger it from a microcontroller. For that I use a MOC3041 to opto isolate my µC from the HV circuit and ...
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561 views

What happens for the SCR if I connect gate with ground when it is turned on?

When I connected a silicon control rectifier by applying positive voltage in anode and negative voltage in cathode, after that I triggered the gate by pulse voltage and it connected, after that I want ...
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881 views

What distinguishes an ordinary thyristor from a GTO thyristor?

A thyristor, I know, is a four-layer PNPN structure, with an anode on the first P section, a gate on the second P section, and a cathode on the second N section. This simple structure suggests that ...
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455 views

Trouble with simulating an SCR

I was reading about SCRs and I'm trying to simulate 2N5060 SCR but having some issues when I plot the currents and voltages: First by looking at the datasheet, I set the R4 to keep the gate current a ...
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377 views

Confused with turn on time definition of an SCR

The following question I encountered is asking about the minimum time for applied voltage to the gate of an SCR to turn it ON: And below is the solution: I can understand the solution looking for ...
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922 views

Testing a thyristor

I have a very large high voltage device that a friend asked me to take a look at. It has a bunch of BIG thyristor packages (Semikron, SKKT 106/18 E, Dual Thyristor Module, 600A 1800V). I'm testing ...
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102 views

Switch operating at particular touch IC voltage [closed]

Is there any circuit to perform such task more efficiently? I am trying to control a small motor (like a smartphone vibration motor) with specific outputs from the touch IC, so that it can be turned ...
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167 views

“Active Low” SCR

Background: I'm working on a circuit that uses an ATmega 328 processor, and a hall effect sensor. We're creating a small wireless sensor, so what we're focusing on now is power consumption. We want ...
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1answer
1k views

Dimensioning SCR crowbar circuit

I need to dimension an SCR crowbar circuit to reach a certain level of protection against overvoltage, without increasing much the complexity of the circuit of my control card. The need is to protect ...
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101 views

What's the best way to detect zero crossing in this design?

The design that I am talking about: I want to be able to detect the zero point with an MCU of which pin can withstand only 3.3 V. I'll forgo optocoupler because A. I want everything to be as cheap as ...
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663 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. ...
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230 views

GTO Driver circuit

i am new to power electronics.I am working in project where input is pulsating dc and i have to control it, i try with scr but we can control only on of scr not off so in some case the cycle cut ...
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551 views

Ideal component to switch 84V DC?

I wanted to control a 84V LED strip using a ATtiny13a microcontroller with minimal power wasted. I just want to turn it on and off, don't need any PWM dimming. The strip uses 270mA current and is ...
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576 views

What is the purpose of the SCR in this circuit?

I am trying to repair an old SMPS. The first step is to reconstruct the schematic and work from there on. The schematic on the low voltage side is completed for the +12V and the +5V circuits. However ...
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128 views

Why Does The NTE5465 SCR In My Circuit Remain Closed, Even With No Current?

See attached circuit. Circuit is designed to have the bulb light, when a very low amperage momentary switch is pressed. In the final circuit, the bulb will draw 4 to 5 amps for a short period of ...
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332 views

SCR switching conducted emissions

I have a circuit that drives a 240Vac line to line power to a resistive load. I am testing for radiated and conducted emissions. Radiated emissions went fine but conducted emissions failed with "broad ...
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233 views

How to know if a SCR is still working?

I'm using a TIC116 to control the power over an electric grill. However, I didn't use a heatsink and it got very warm. On the data it says that its upper limit is 110 °C. I suspect that the gate is ...
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234 views

Problem with using SCR to control power for an electric grill

I'm doing a power controller for an electric grill, where through PWM I allow to pass x number of cycles from the 124V @ 60 Hz source of my lab. Here you have the diagram: simulate this circuit &...
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3k views

Why are bulky SCR power controllers used when the same can be achieved with a relay?

This is kinda noob question. I recently got an SCR Power controller (WATLOW DIN-a-mite DB20-24CO-0000 Style B). This is the first time I actually got to test an SCR controller for myself. The input ...