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#1 grippleboy


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Posted 11 May 2004 - 07:54 PM

what problems would you encounter operating thyristors from a dc supply;

#2 marke


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Posted 12 May 2004 - 06:20 AM

Hello grippleboy

Welcome to the forum.

Thyristors are usually either SCRs or Triacs, and both of these devices are switches that can be easily turned ON but not easily turned OFF.

The SCR is a rectifier, (passes current in one direction only) that is normally OFF (blocks current in both directions) and can be turned ON (conducts forward current only) by applying a pulse to the gate.
To turn the SCR OFF, you must interrupt the current flow through the device, and this requires another switching device in series. You can not turn an SCR OFF by use of the gate terminal.

A Triac is like an SCR except that when it is turned ON, it can conduct current in bothe directions. It is similar to two reverse parallel connected SCRs with only one gate.

To answer your question, we would need to know what you want to do from the DC supply, but if you were to use an SCR to control a lamp from a DC supply, once turned ON, the almp would not go out until you interrupted or bypassed current flow through the SCR.

Give us more detail and we may be able to help further.

Best regards,

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