SCR problem (always conducting)

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Harold
Level 1
Level 1
10 questions asked 10 sign-ins 5 questions asked

I have recently been messing around with some SCR's. I am aware that once you activate the SCR's gate the SCR will start conducting and remain conducting even if the gate is removed as long as the cathode to anode potential difference is favorable. The issue I am having is that my SCR conducts no mater what. I remove wiring from the gate before applying voltage to cathode, I ground the gate before applying voltage to the cathose, either way the SCR conducts. I have bought 10 SCR's (2N6403) I have tried brand new ones with no gate connection, cathode to 5V and anode to ground etc. still conduction persists. I am very confident that the new ones I have tested have not been internally shorted/damaged. It seems which ever method I use I continually get a conducting SCR without having induced it. If anybody has any input on the subject it would be greatly appreciated.

Thank you.

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Anshika_G
Moderator
Moderator
Moderator
First question asked 50 likes received 250 replies posted

Hello Harold,

Thank you for posting on Infineon Community.

Regarding your query, please let me know the following:
1. What are the different voltage levels you are trying to use or apply to SCR?
2.  As you have mentioned that you are applying cathode to 5V and anode to ground, I am not able to understand why are you using a reverse polarity connection?
Because for an SCR to operate in normal mode, the connection should be from anode to cathode.

Thanks and Regards,
Anshika

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Anshika_G
Moderator
Moderator
Moderator
First question asked 50 likes received 250 replies posted

Hello Harold,

Thank you for posting on Infineon Community.

Regarding your query, please let me know the following:
1. What are the different voltage levels you are trying to use or apply to SCR?
2.  As you have mentioned that you are applying cathode to 5V and anode to ground, I am not able to understand why are you using a reverse polarity connection?
Because for an SCR to operate in normal mode, the connection should be from anode to cathode.

Thanks and Regards,
Anshika

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