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I'm curious if there is a way to reverse the way an SCR works(Current flow to load UNTIL a gate signal arrives). I think this would come in handy for a bunch of hobby circuits I may want to design/build. I tried the following to test out the only way I could think to do it, but it did not work...

My test schematic

Anyways, is it possible to do this and if so, can someone post a schematic of how this is accomplished?

[Edit by OP]

I just tried this, but still no luck...

enter image description here

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  • \$\begingroup\$ "Current flow to load UNTIL a gate signal arrives" ... Ok, I get that you want the current to stop at this point, but what condition (if any) do you want to resume current flow to the load? Reset button? Cycle power? Release of gate signal? Timeout? Something else? \$\endgroup\$ – Tut Apr 1 '14 at 11:58
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I think the problem with both proposed circuits is that the hold-current through the SCR is not met. Probably not the most elegant solution, but the easiest way to fix your circuit is with the lower one. Basically make sure there is a current flowing through the SRC (5mA minimum according to the datasheet), and limit the base current of the transistor.

schematic

simulate this circuit – Schematic created using CircuitLab

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  • \$\begingroup\$ Thanks! I will try that later on today and get back to you on how it works out! \$\endgroup\$ – Zack Frost Mar 2 '14 at 15:22

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