Turn off a transistor with another transistor or a switch?

Thread Starter

sciengart

Joined Mar 25, 2020
36
Hey guys and gals,

this one should be pretty easy, I am 100% certain it can be done...
I can short an led between a resistor and ground, that will turn off the led.
That part I grasp. But teacher google can't seem to answer this one for me so I am turning to you.

I want to switch off a transistor with another switch.
I feel like this is the role of the pnp, but i really dont use pnp much so I have no idea.Z

Thanks for any help.
While I wait as always, I will try to solve it on my own.
 

DickCappels

Joined Aug 21, 2008
7,553
I think you figured it out. If you replace the LED anode and cathode with the base and emitter respectively of the transistor you are turning off, yes. That will work.
 

ElectricSpidey

Joined Dec 2, 2017
1,762
You turn off a transistor by bringing its base/gate to the same potential as its emitter/source.

You can also turn off a BJT by depriving its base of current, (open the circuit)

That's the condensed version.
 

Dodgydave

Joined Jun 22, 2012
10,035
Hey guys and gals,

this one should be pretty easy, I am 100% certain it can be done...
I can short an led between a resistor and ground, that will turn off the led.
That part I grasp. But teacher google can't seem to answer this one for me so I am turning to you.

I want to switch off a transistor with another switch.
I feel like this is the role of the pnp, but i really dont use pnp much so I have no idea.Z

Thanks for any help.
While I wait as always, I will try to solve it on my own.
Here is an example, Q1 shorts Q2 B/E thus turning it off...


NV_0903_Marston_Figure03.jpg
 
Top