All Questions
51 questions
0
votes
2
answers
104
views
Using IGBTs for controlling heating loads
I know traditionally antiparallel connected SCRs (Thyristors) are used in phase-angle control mode to control the heat delivered to an industrial furnace or to control heating loads. Can the same be ...
0
votes
1
answer
51
views
Why does adding an LCD to my Arduino project break the controlling of the SCR?
I found this project which is about controlling the firing angle of SCR using Arduino and it works well.
https://simple-circuit.com/arduino-scr-half-wave-controlled-rectifier/
Then I modified the code ...
- 1,940
4
votes
2
answers
100
views
SCR not latching when triggered [closed]
I am attempting to design a circuit to discharge an electrolytic capacitor through a bleeder resistor when someone breaks the line of sight between an IR emitter and phototransistor as a safety ...
- 87
1
vote
0
answers
27
views
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 ...
0
votes
1
answer
174
views
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 ...
- 155
0
votes
2
answers
130
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 ...
- 77
0
votes
0
answers
191
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 ...
- 23
2
votes
1
answer
164
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 ...
0
votes
0
answers
195
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 ...
- 155
0
votes
1
answer
91
views
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 ...
- 593
2
votes
1
answer
76
views
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 ...
- 593
0
votes
1
answer
3k
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 ...
- 45
1
vote
3
answers
606
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 ...
- 11
2
votes
1
answer
1k
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 ...
- 285
1
vote
2
answers
154
views
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?
...
- 593
0
votes
1
answer
175
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 ...
0
votes
0
answers
50
views
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 ...
0
votes
0
answers
80
views
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 ...
- 366
0
votes
3
answers
391
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, ...
- 101
0
votes
0
answers
196
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:...
- 465
0
votes
2
answers
451
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-...
- 465
0
votes
1
answer
341
views
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 ...
- 366
2
votes
2
answers
4k
views
SCR inverter (thyristor H-Bridge) schematics/working principle?
Several online articles mention the so-called "Single phase SCR Inverter". Sample schematic is attached below.
Source: Single Phase Full Bridge Inverter Explained | Electrical Concepts
In ...
- 392
0
votes
1
answer
207
views
If you have a MOSFET in series with a thyristor, can turning the MOSFET off cause the thyristor to turn off?
This is a purely theoretical question. The values in the circuit below do not matter, and I understand the circuit is completely useless.
Consider if SCR1 and M1 are both turned on so that current is ...
0
votes
1
answer
207
views
control ac motor with SCR
I want to repair the circuit of a Mixer that used the TS820 thyristor.
The other components were healthy except the thyristor so I replaced the TS820 with the BT151 but the circuit did not work.
Now I ...
1
vote
1
answer
159
views
Common Ground across SCR and Diode Bridge
I am trying to use a common ground to enable a regulated output across the circuit, however as you can see the SCRs and Bridge use the common earth to relay the positive channel in the bus..
Is this ...
- 177
0
votes
4
answers
3k
views
How does a capacitor and resistor affect an SCR's firing angle?
Greetings! High schooler here studying SCRs. I've been looking at sites and books on the concept of increasing an SCR's firing angle, and what I've noticed with these references is that they show you ...
1
vote
1
answer
80
views
A question on thyristors and phase control
High schooler here reading on thyristors.
Videos online and books say they can be used as light dimmers. I assume that's because we can control the amount of current that can enter a load. But what ...
1
vote
1
answer
377
views
Controlling underdamped LC circuit with thyristor
I am trying to design a circuit that gives me an underdamped sine wave.
I am controlling the SCR from an external transformer by microcontroller.
When I simulate this circuit, V3 has no effect on the ...
- 79
2
votes
1
answer
132
views
What type of vintage semiconductor device is this? Is it an SCR?
I found this circuit board from an 1980s old humidity controlled chamber. This definitely looks like a temperature regulator of some sort. It has a M logo which means made by Motorola. It has the ...
- 1,524
4
votes
2
answers
1k
views
Thyristor SCR gate trigger
I'll work for the first time with a Hockey Puck type SCR with a high di/dt application. So far I've mounted it properly, with the proper clamp and heatsinks. Now I'm concerned with the gate drive, ...
- 155
1
vote
1
answer
301
views
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,...
- 91
3
votes
1
answer
1k
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 ...
- 45
1
vote
0
answers
2k
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 ...
- 13
-1
votes
3
answers
499
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?...
user234225
1
vote
0
answers
47
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 ...
0
votes
1
answer
66
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 ...
- 101
0
votes
3
answers
920
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 ...
- 141
10
votes
1
answer
2k
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 ...
- 38.5k
3
votes
3
answers
3k
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 ...
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.
...
- 71
0
votes
1
answer
2k
views
How do I find the firing angle of SCR practically? [closed]
Our teacher told us to find out the time period and then multiply it by 18.Then 180-(∆t*18) gives firing angle.Why 18 as a multiplier?
- 55
1
vote
1
answer
3k
views
LTSpice Simulation Problem - Controlled Rectifier Single Phase Dual Converter
So I am having problems simulating a Single Phase AC/DC Dual Converter on LTSpice. At the first converter I am getting the perfect output but when I take the voltage probe from the second converter ...
- 11
1
vote
2
answers
4k
views
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'...
- 1,191
3
votes
2
answers
1k
views
thyristor equation
I know how does an I-V curve of a thyristor look like, but is there any thyristor equation that can represent the curve?
- 33
0
votes
1
answer
3k
views
Is it possible to replace a DIAC circuit with an SCR circuit to drive a TRIAC
I have a triac DIAC cirtcuit. I don't have any DIACs on hand, but I do have plenty of TN1215s. Is it possible to generate the required pulses using an SCR to drive the TRIAC's gate?
- 2,417
1
vote
2
answers
624
views
Why are the wires of thyristors always twisted in pairs?
I have always been told that you should never untangle the wires of a thyristor or subset of thyristor (such as TRIAC and SCR). Why is this? Is this just for convenience or is there a use for the ...
- 615
0
votes
2
answers
1k
views
SCR "current gain" - calculating gate resistance
Trying to understand the SCR. Have made this outlay which I shall find the right resistors for.
edit
or
The SCR is a TYN1225
But since I have found it difficult to understand \$I_{GT}\$ and \$V_{...
- 88
1
vote
2
answers
923
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 ?
- 300
1
vote
2
answers
2k
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 ...
- 357