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LED control via a reed switch and SCR Answered

n00b question:

I've got an RGB LED that has a forward voltage of
3.7v and a 3.7v battery pack. I want to trigger the
LED to light via a magnet and reed switch. If I wire
the reed switch to the gate of the SCR and have
the SCR power the LED, will I be able to turn the
LED on and off via the magnet by bringing the
magnet near the reed switch?


4 Replies

steveastrouk (author)2013-02-22

SCR's can't be turned off by turning off the trigger. Why use an SCR ? The reed switch is all you need - and a resistor to the LED

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d0ugparker (author)steveastrouk2013-02-22

Ah, yes, that would work with the magnet remaining nearby,
but I want to latch the LED so it continues to run after taking
the magnet away. Then I want to power the LED off with the

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Orngrimm (author)d0ugparker2013-02-23

Then you need to feed the signal from the reed-switch to a toggle-flipflop which in turn needs a supply-voltage of at least 3V or even 5V.

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steveastrouk (author)d0ugparker2013-02-22

Ah, now that's a completely different problem, and an SCR won't help that one either !! For that, you either need a couple of relays or a small logic chip

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