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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How to turn off charging while SCR is latching?
So I'm trying to make a CDI for my old motorcycle that can be controlled using Arduino, after a bit of research (mainly Googling) and prototyping I come up with this design, this design has been ...
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How does this half bridge inverter charger charge the battery?
I just can't understand how this inverter charger actually charges the battery. The charging circuit uses two SCRs on the mains side of the transformer. The same transformer is also used to step up ...
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Will Any SCR Trigger Optically If It Is Exposed To Light?
I read somewhere that all SCR's are photosensitive, in the same way that all diodes emit light, but some are optimized to take advantage of this property while others are not.
There is an SCR I want ...
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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 ...
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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 ...
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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 ...
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Can I use a voltage divider instead of an external battery with an SCR?
I have this circuit
12VDC battery
boost converter up to 390V DC-DC
capacitor 1000 uf 450V
diode 10A10
thyristor BTW69-1200 (I gt 8-80 mA / V gt 1.5v max)
I managed to make this circuit work with an ...
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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 ...
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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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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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Can I make active devices share voltage equally using ad hoc shunt resistors?
I have 3 active devices in series, SCRs in this case but I'm guessing that's not important. Each is rated for 2.4 kV. The total voltage I will actually apply is 6.6 kV.
Leakage current is guaranteed ...
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In practice, is the ganging of a large number of SCRs in parallel often more expensive than an equivalent hockey puck?
In a separate but related question, I asked how EEs normally wire a large number of SCRs in parallel for high current applications. For this 1 example (sample size = 1), I found a single hockey puck ...
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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?
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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 ...
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Different firing angles of SCR
Considering this circuit, what would happen if T1 and T2 had different firing angles, let's say 45° for T1 and 60° for T2?
Is it the same thing as both of them having 60°? (I think that the circuit is ...
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What is the purpose of the unijunction transistor in this circuit?
Trying to figure out the purpose and functionality of this circuit. Apparently, this is some sort of temperature controller. There is no information on parts values or the load type (heater, probably?)...
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Trying to get a 10uS pulse width to fire an SCR using a PIC16F884
I have the circuit built and running but I need to shorten the pulse width of the SCR. I am using a PIC16F884 running at 16MHz. I am using a half wave to control a device. When I use a for next loop, ...
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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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Will swapping a SCR with an SSR increase max current?
We have a system at my work that controls a furnace via a NI cRIO. This circuit currently uses a SCR (model listed below) with the cRIO to switch power out to the furnace. I don't want to get into the ...
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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, ...
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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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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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Cheapest solid-state way to turn a 240 VAC, 15 W resistive load on/off
I need to be able to pulse a 240 VAC, 15 W resistive load on and back off. I need it to turn on only for a single line cycle, then it will remain off for at least 60 seconds, so perhaps the components ...
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How to determine saturation in DC smoothing choke with capacitor, and how to simulate in LTspice?
This question addresses some of the issues with a choke made from a microwave oven transformer for producing smooth DC from a phase-fired SCR controller, as discussed in this question.
The choke ...
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What is the reason for the "back porch" current requirement on an SCR gate driver?
I am studying SCR gate drivers at the moment and I would like to understand their fundamentals.
Looking at a SCR datasheet (for example, this one section 7 or this application note fig 6 p4,) one see ...
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What is minimum holding current in CT based SCR switch?
I am looking to use a CT based SCR switch to switch an AC contactor. The switch specs list the following:
Off state voltage: 240 VAC RMS max.
Minimum holding current: 10 mA.
On state current: 1.0 AAC ...
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Kiln SSR zero-cross frequency
I am planning on using a WATLOW DC2T-24C0-0000 power controller for a three phase electric kiln.
It is a zero-cross 3 phase, 2 leg controlled contactor capable of driving 46 amps with its huge heat ...
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How do I calculate the potentiometer value for the controlling of Alpha angle of a phase control IC? [closed]
The datasheet suggests to use a 10Kohm pot to control the Alpha angle, however no matter how much I try I can't control it. I used 1Mohm pot instead and now I can control it more, but still with very ...
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Why aren't smoothing capacitors used in smoothing the output of fully controlled bridge rectifiers?
I was wondering why smoothing capacitors are not used in smoothing the output of fully controlled bridge rectifiers, like it is used in the uncontrolled bridge rectifiers.
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Recommendation for optocoupler for SCR and TRIAC Gate driver
I want to use an SCR having gate current "Igt" = 50mA and a TRIAC with Igt = 50mA to 100mA. I am looking for an optocoupler IC to drive the SCR and TRIAC. I saw MOC3021 but it's "LED ...
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How I can calculate the switching frequency of an SCR and replacing diode with SCR in boost converter? [closed]
I want to find the switching frequency of SCR. I want to use an SCR or a GTO thyristor so I can use a switching frequency up to 20 kHz, but as I am new so I am unable to find the SCR frequency from ...
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Semi-controlled full wave rectifier
First, a little background.
I picked up a Canadian-made 1971 Lincoln Idealarc 250 on the cheap with the intention of turning it into a constant voltage capable machine for wire processes. The fan ran ...
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Is it possible to use an MOV instead of a flyback diode in a pulse circuit?
I am working on a small high-voltage pulse circuit to protect my animals. I have a question about the flyback diode D2 to protect the SCR.
The flyback diode seems to waste a lot of energy between ...
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SCR inverter (thyristor H-Bridge) schematics/working principle?
Several online articles mention the so-called "Single phase SCR Inverter". Sample schematic is attached below.
In reality, this, of course, will not work, since SCR2 when activated after ...
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Need help building simple burglar alarm circuit
I'm trying to build a simple burglar alarm circuit and I've found one online that uses a knife switch, 9 V power source and an SCR. I'm trying to change it over to a PIR motion sensor but am unsure ...
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How to control voltage using PID when driving SCR?
I am designing a scr based digital battery charger for the first time and have successfully driven scr to provide 110V-DC from a 140V singe-phase transformer. 2 SCR-diode combination forms full bridge ...
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Turning on SCR without latching it
The picture shows a typical SCR circuit. I have already simulated this circuit in multisim. Since multisim assumes this to be an ideal SCR (zero voltage drop for example,) the characteristics may not ...
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SCR latching current and holding current equivalent definition
understanding the definitions of Latching and holding current.
suppose a particular value of the gate current I_g is given. Now that we increase the voltage across the SCR from 0V and onwards. Forward ...
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What circuit is used in industry for SCR firing?
I am a hardware developer. I have a requirement for designing a firing card for SCR. I am not very used to using thyristors and it has been a long time since I used one.
I see on the internet there ...
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SCR bridge control circuit
I want to design a single phase 400V 1A power supply using mains (230VAC,50Hz). For which I plan to use a step up transformer which will step up to 400V and then an SCR Bridge rectifier to convert it ...
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Industrial SCR rectifier/battery charger circuit: best place for blocking diode, reverse diode, and dropper diodes?
I am working on a three phase 110 VDC & 100 A SCR rectifier/battery charger. I'm not sure which one of the circuits in the image is better for filter and diodes. Please help me with these ...
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How to build a DC motor speed controller with DC source and SCR?
So after asking a question from the book "Practical electronics for inventors" and getting recommendations to burn the book, I'm going to start this thread with the premise that I'm not ...
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Replacing Darlington with MOSFET for capacitive discharge circuit into a solenoid?
I have the following circuit and criteria and am wondering if it makes sense to replace the Darlington transistor with a MOSFET, and if so how would that change the circuit? This circuit turns on T1 ...
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How does this Snap Circuits SCR circuit work?
I came across some custom Snap Circuits projects. One of them was a homemade SCR out of non polarized capacitors, two bipolar (NPN) and (PNP) transistors, some resistors, and an L.E.D. I am very ...
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3 phase controlled soft starter and motor vibration
I want to make a soft starter for 3 phase induction motors. TRs are SCR pairs and ZCs are the zero-cross timing respect to line voltages (400V), not phase voltages (230V). I control the firing angle ...
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Can a Triac be driven using only positive voltage due to the laws of Q1 and Q4 quadrants?
I have a BTA12-600B Triac and an Arduino.
Is it possible I can trigger both positive and negative amplitudes of an AC cycle by suppling only a positive voltage from the Arduino digital pin to the ...
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How does this regulator/rectifier circuit work?
I am working with the following circuit from a motorcycle. It provides 13.8V DC out from a 15V-100V AC generator input.
I understand how the bridge rectifier (BR1) and smoothing capacitors (C1, C2) ...
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SCR vs diode VI characteristics
We know in an SCR when in conduction mode, triggered by some gate voltage, the lower three junctions will essentially turn into a single N junction and so the SCR essentially becomes a PN junction ...
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