The data sheet for the SCR BTW67-1000 is not clear as to which pin is the gate. The diagram shows a pin to be parallel to the centre line of the mounting holes but on the device there is no pin as such. Is the smaller pin with a smaller hole the gate

[Abrid.11]

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[Saurabh SONA]

Yes, the smaller pin with smaller hole should be the gate. With the flat surface facing down and the gate pin oriented towards you, the pin on the right of gate pin is A while the left pin is K. This info is missing in the DS0642 - Rev 6 of the device currently available on ST website. I was able to verify the info from Ver 5 of the datasheet discovered through online search.