UK 70TPS12 Thyristor - Help!

[mainline]

Can you tell me which pin you think is the gate? 1, 2, or 3? From the photo I think it’s pin 3, but thought I would get a second opinion. Thanks!

 

[mangoelectrics]

Looking at some data sheets the gate should be the one you've got marked up as 3. Also the minimum gate current to turn on should be 100mA.

Thanks both of you. That’s very helpful to know for sure which is which. If I put - to the gate then the led or motor immediately is powered continuously even without the negative lead going into pin 2.

Hope this helps.

 

[mainline]

use a lamp or a motor.

Connect one wire of the motor to - of the battery.
Connect the other side of the motor to the K of the Thyristor.
Connect the A of the thyristor to + of the battery.

Connect a 1k resistor to G of the thyristor and - of the battery.

Power the circuit the motor shouldnt run.

If you run a bit of wire from + of battery and just touch it on to the Gate of the thyristor the motor should run and continue to run.

 

[mangoelectrics]

use a lamp or a motor.

Connect one wire of the motor to - of the battery.
Connect the other side of the motor to the K of the Thyristor.
Connect the A of the thyristor to + of the battery.

Connect a 1k resistor to G of the thyristor and - of the battery.

Power the circuit the motor shouldnt run.

If you run a bit of wire from + of battery and just touch it on to the Gate of the thyristor the motor should run and continue to run.

Will try this in the morning, thanks for your help!

 

[mangoelectrics]

use a lamp or a motor.

Connect one wire of the motor to - of the battery.
Connect the other side of the motor to the K of the Thyristor.
Connect the A of the thyristor to + of the battery.

Connect a 1k resistor to G of the thyristor and - of the battery.

Power the circuit the motor shouldnt run.

If you run a bit of wire from + of battery and just touch it on to the Gate of the thyristor the motor should run and continue to run.

Just tried that now. It does work as you say it should although it takes the positive power in through the gate pin and does not seem to activate the thyristor. Do you know why this might be?

Thanks again!

 

[mangoelectrics]

Also, when I remove the 1k resistor from - to gate then power the gate with + 5v the motor immediately runs, but does not continue to run after I remove the power to the gate, it should continue to run as I have permanent power to the K and A of the thyristor.

Im beginning to think my thyristors are no good?

Thanks!

 

[mangoelectrics]

@Moley Do you have any suggestions?
Thanks!

 

[mainline]

Also, when I remove the 1k resistor from - to gate then power the gate with + 5v the motor immediately runs, but does not continue to run after I remove the power to the gate, it should continue to run as I have permanent power to the K and A of the thyristor.

Im beginning to think my thyristors are no good?

Thanks!

What test gear have you ? I think you should have a read up on how to test scrs.

There are lots of videos on basic electronics etc i think you need to learn a bit more, especially when dealing with mains supplies.


If you just want to switch a higher voltage with a lower one then just use a contactor.

View: https://www.youtube.com/watch?v=dCEt_oaFPMY

 

[mangoelectrics]

What test gear have you ? I think you should have a read up on how to test scrs.

There are lots of videos on basic electronics etc i think you need to learn a bit more, especially when dealing with mains supplies.


If you just want to switch a higher voltage with a lower one then just use a contactor.

View: https://www.youtube.com/watch?v=dCEt_oaFPMY

Thanks, let me explain a bit further.

According to the video, mine are no good. They have measurements of between
G and K: 138 Ω
K and A: 63M Ω and always rising
A and G: 76M Ω and always rising

I am building a coil accelerator and so am needing to use the thyristor to switch on the coil when I give the command. But obviously I am running a 1900uf 450V DC capacitor charged to 400V DC so when I fire it, it gives a HUGE amount of power instantly and this was burning out normal switches.

This is why I was trying to use a thyristor. But if you have another idea of what I could use I would be happy to try that.

Thanks again!

 

[mainline]

Thanks, let me explain a bit further.

According to the video, mine are no good. They have measurements of between
G and K: 138 Ω
K and A: 63M Ω and always rising
A and G: 76M Ω and always rising

I am building a coil accelerator and so am needing to use the thyristor to switch on the coil when I give the command. But obviously I am running a 1900uf 450V DC capacitor charged to 400V DC so when I fire it, it gives a HUGE amount of power instantly and this was burning out normal switches.

This is why I was trying to use a thyristor. But if you have another idea of what I could use I would be happy to try that.

Thanks again!

If you have used those scrs on a coil the back emf may have destroyed them you would need a diode to stop that.

 

[UKMeterman]

A number of points. It needs a continous current of 100mA to hold it on,.
2. A motor has a comuninator in it, so the current is lumpy and so can drop below 100ma
3. You need to arrange safe isolation between the 400V and your control circits.
4. 400V with that capacitor will kill you.
5. You need a current limiting element in that circuit or stuff will blow up.


If you need this kind of help I wouls suggest you need to consider if you are competent to be working with 400V dc.

 

[mangoelectrics]

THREAD CLOSED

This issue has now been resolved.

Here is the final working schematic:

 

[mainline]

A number of points. It needs a continous current of 100mA to hold it on,.

An scr will latch on once triggered and will stay in that state even with no gate current.

2. A motor has a comuninator in it, so the current is lumpy and so can drop below 100ma

The motor will continue to run until the positive voltage at the anode stops.

 

[mangoelectrics]

An scr will latch on once triggered and will stay in that state even with no gate current.


The motor will continue to run until the positive voltage at the anode stops.

THREAD CLOSED

 

[mainline]

THREAD CLOSED

Is it ?? you could have fooled me.

 

[mangoelectrics]

Is it ?? you could have fooled me.

It is now working! STOP arguing please!

THREAD CLOSED

 

[mainline]

It is now working! STOP arguing please!

THREAD CLOSED

Nobody is arguing.
Misinformation is better to be corrected than just left.

 

[mainline]

If your circuit shows a transformer you cant drive it with DC
Transformers work by the principle of electromagnetic induction. A changing current in the primary coil (the input) creates a changing magnetic field, which then induces a voltage in the secondary coil.