UK 70TPS12 Thyristor - Help!

[mangoelectrics]

Hello All,
I am new here and I don't know if I'm posting in the correct place but I need some help with wiring up my Thyristor.

I have added below a photo of my thyristor.

I don't know why, but I cannot get it to work as a switch.

I will be running the gate off around 1.4v DC and I need to be able to switch around 400v DC.

I am simply trying to use it to switch off and on a 400v DC supply.

Any answers would be much appreciated!

 

[mangoelectrics]

Also, if I test across pins 1 and 3, I get an ohms rating of 120 Ω. But across pins 2 and 3 or 1 and 2 there is nothing.

 

[James]

http://www.datasheet.hk/download.php?id=1843527&pdfid=5535644E9C5EC6C2EE5E0CCF73222D96&file=0423\70tps16_5025539.pdf

 

[mainline]

Hello All,
I am new here and I don't know if I'm posting in the correct place but I need some help with wiring up my Thyristor.

I have added below a photo of my thyristor.

I don't know why, but I cannot get it to work as a switch.

I will be running the gate off around 1.4v DC and I need to be able to switch around 400v DC.

I am simply trying to use it to switch off and on a 400v DC supply.

Any answers would be much appreciated!

Is the circuit switching at all ?
can you show the circuit your proposing ?

 

[mainline]

I suggest using a battery circuit before playing with the higher voltage.

 

[mangoelectrics]

I suggest using a battery circuit before playing with the higher voltage.

Yep, that's exactly what I have been trying all day!

Will try to send you a schematic of my mini battery test circuit soon.

Thanks!

 

[mangoelectrics]

@mainline Here is the schematic. What I want is when I press S1, it should then light up LED 1. That is, if I have connected everything correctly!!! Hope this helps, and thanks for your help so far!

 

[mangoelectrics]

@mainline This is what it looks like. I am using an Arduino to power it with 5V just for testing purposes.
Thanks!

 

[mainline]

@mainline Here is the schematic. What I want is when I press S1, it should then light up LED 1. That is, if I have connected everything correctly!!! Hope this helps, and thanks for your help so far!

Once the thyristor switches on its going to latch on.
looks like your led is the wrong way around.

Have a read of this.

https://www.electronics-tutorials.ws/power/thyristor-circuit.html

 

[mangoelectrics]

Still nothing. Tried reversing the LED and still no light.

When I try this schematic below, it immediately lights up when plugged in, then when I press S1 the light goes out and immediately comes back on when S1 is released.

Obviously the power to the LED (LOAD) is coming through the 1k ohm resistor going into the SCR Gate.
When I remove that resistor the LED goes out and does not come on when the switch is pressed. Also if I leave the resistor in and remove the Negative lead to pin K of SCR the LED still works without the S1 pressed.

Still can't find the issue!!!

 

[mainline]

Still nothing. Tried reversing the LED and still no light.

When I try this schematic below, it immediately lights up when plugged in, then when I press S1 the light goes out and immediately comes back on when S1 is released.

Obviously the power to the LED (LOAD) is coming through the 1k ohm resistor going into the SCR Gate.
When I remove that resistor the LED goes out and does not come on when the switch is pressed. Also if I leave the resistor in and remove the Negative lead to pin K of SCR the LED still works without the S1 pressed.

Still can't find the issue!!!

Have you tried a resistor from the Gate to -

 

[mangoelectrics]

Have you tried a resistor from the Gate to -

Yes, here is another photo.
It lights up VERY dim. Obviously the only negative input is from the resistor coming through the gate pin.

Sorry, very poor image!

 

[mainline]

Yes, here is another photo.
It lights up VERY dim. Obviously the only negative input is from the resistor coming through the gate pin.

Sorry, very poor image!

have you a lamp or something instead of an led to try.

 

[mangoelectrics]

Will try something and get back to you on Monday. But thanks very much for your help so far!

 

[mangoelectrics]

have you a lamp or something instead of an led to try.

Just connected up a dc motor and have the same results as with the LED.

 

[mainline]

Just connected up a dc motor and have the same results as with the LED.

try another thyristor

 

[mangoelectrics]

try another thyristor

No difference!!!

 

[mainline]

No difference!!!

What happens if you put the gate to - and then power the circuit



What do you actually want to do ?

 

[mangoelectrics]

What happens if you put the gate to - and then power the circuit



What do you actually want to do ?

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!

 

[Moley]

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.