Hey everyone,
I've been trying to understand (NPN) transistors (i.e. BJTs) for the past two weeks now. I think I understand the basic rules about active, saturation and cut-off now, and I even got some simple inverters to work.
However, they're probably drawing way too much current, and thus influencing the rest of my circuit. I chose my resistor value for the base transistor to be 100 ohms, however, that was like a complete guess, and it just worked, although only when operating alone... so not quite useful ...
So, I started reading a lot of texts about how to calculate the correct values.
My calculations can be found below...
So I want a couple of things to happen:
- The output of the inverter should be 20 mA and 2V
- Exactly all output current should be drawn by the collector of the transistor when I supply a 2V voltage on the base
I calculated that R1 (see picture below) should be 50 ohms, and that was (probably ) correct, since it seemed to work in a simulator. However, R2 probably isn't, and R3 is absurd (negative!)
I greatly appreciate any help!!
Thanks a lot in advance!
Regards,
Abel.
Original Size image
I've been trying to understand (NPN) transistors (i.e. BJTs) for the past two weeks now. I think I understand the basic rules about active, saturation and cut-off now, and I even got some simple inverters to work.
However, they're probably drawing way too much current, and thus influencing the rest of my circuit. I chose my resistor value for the base transistor to be 100 ohms, however, that was like a complete guess, and it just worked, although only when operating alone... so not quite useful ...
So, I started reading a lot of texts about how to calculate the correct values.
My calculations can be found below...
So I want a couple of things to happen:
- The output of the inverter should be 20 mA and 2V
- Exactly all output current should be drawn by the collector of the transistor when I supply a 2V voltage on the base
I calculated that R1 (see picture below) should be 50 ohms, and that was (probably ) correct, since it seemed to work in a simulator. However, R2 probably isn't, and R3 is absurd (negative!)
I greatly appreciate any help!!
Thanks a lot in advance!
Regards,
Abel.
Original Size image