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vivek_pv
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The thing is:

There is one circuit which is "normally closed" so that one LED is on.
If one particular signal comes, I want, that the "normally closed" circuit should be open, till that signal lasts.

This I can do it by a relay. But I wish to know what is the transistor equivalent for this type?

Regards,
Vivekanand

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A transistor can easily turn an LED on and off, and be controlled by certain types of signals, but you don't say the details of your signal.
We need to know the voltages and currents of the signal when it is active and when it is inactive. Also we need to know if it is DC or AC.

If your signal is too complicated to describe in words then attach its schematic.

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Hi,

I am attaching the schematic design of this. It is not so complicated design. Rather very simple.

Details : Source = 3V DC, Always the path AB is closed (NC). If I press the switch, then the closed path of AB should be cut off as long as the switch is closed.

I hope it is clear.

regards,
v

post-22103-14279143019632_thumb.jpg

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Hi,

Ofcourse, there is nothing in the dotted square. It is to show the point of question only.

I know about push to break switches and relays to do this.

But basically I need such transistor topology to adapt in my various projects.

I will be grateful if one tells me how to use transistors to do this.

regards,
Vivekanand

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This simple transistor circuit will turn on the LED because the 3.3k resistor applies base current to the transistor when the switch is open. Then the transistor and LED turn off when the switch is closed.
The battery will have the 0.9mA of the 3.3k resistor as a current when the switch is closed.

post-1706-14279143019848_thumb.jpg

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Is this the only way to create?

No. Transistors can be used as switches many other ways.

is there any other way so that battery power is saved? (When this switched is closed, the 3.3k will consume some little current)

Yes. You can add a 2nd transistor to make your own darlington transistor or buy a darlington transistor. Then the 100k resistor consumes very little current. See my modified schematic

Is this model called a "digital inverter"

No. It is a transistor inverting switch. A digital inverter inverts a digital voltage level or pulse.

post-1706-14279143019919_thumb.jpg

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