Calculating the base and the collector value of the transistor with base voltage restriction

Thread Starter

Ashad@27

Joined May 28, 2021
5
The voltage at the base will never be more than about 0.7V. As it approaches that level, the transistor will turn on, and the current will flow from the 3.3V supply through the 10K resistor and drop Vce(on) across the collector-emitter junction. As AGA has mentioned there is no way to make this circuit reliable and repeatable. Every transistor will be different.

Here is a simulation that shows the transistor threshold in the neighborhood of 590mV to 605mV and Vce(on) at about 6mV. I can change the base resistor and the voltage won't change much.
What if we increase the base resistor to decrease the voltage at the base when we give a 1.3V input,Please correct me if I am wrong
 

Thread Starter

Ashad@27

Joined May 28, 2021
5
Not the way I read it at all. I think he wants 5V on the right end of the 4.3K resistor in his drawing to turn the transistor on, and 1.3V to turn it off.

Bob
You are right, how can I drow this 1.3V through a base resistor so that the transistor turned off
 
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