Hello,
I'm trying to understand the sorcery that transistors / semiconductors are…
Given this simple circuit (battery=9v, P1={0-100k ohm}, t1 has Hfe of about 330)
as far as I understand, once a semiconductor (like a diode or base-emmiter) is put in parallel with one of the resistors, ohm's law takes a break and goes fishing and voltage divider is no more, right?
In my tests, I got the following results:
|P1 |Vb |Ib |Ic |
4k 0.5 57uA 20mA
7k 0.53 111uA 40mA
17k 0.54 156uA 60mA
100k 0.5 177uA 80mA
that's actually pretty close to what the simulator predicts. However, I have no clue whatsoever how that potentiometer controls Ib and what the relation between its resistance and Ib is?
As far as I understand the voltage divider kinda works to the point when base actually starts opening, say about 0.5V, and after that point the voltage is constant (same as would be for a diode) and Ib starts growing. What is the formula for tor calculating Ib in relation to R2? What do I need to read to understand the basics of this (and not going all down to quantum level and holes etc).
Thanks
I'm trying to understand the sorcery that transistors / semiconductors are…
Given this simple circuit (battery=9v, P1={0-100k ohm}, t1 has Hfe of about 330)
as far as I understand, once a semiconductor (like a diode or base-emmiter) is put in parallel with one of the resistors, ohm's law takes a break and goes fishing and voltage divider is no more, right?
In my tests, I got the following results:
|P1 |Vb |Ib |Ic |
4k 0.5 57uA 20mA
7k 0.53 111uA 40mA
17k 0.54 156uA 60mA
100k 0.5 177uA 80mA
that's actually pretty close to what the simulator predicts. However, I have no clue whatsoever how that potentiometer controls Ib and what the relation between its resistance and Ib is?
As far as I understand the voltage divider kinda works to the point when base actually starts opening, say about 0.5V, and after that point the voltage is constant (same as would be for a diode) and Ib starts growing. What is the formula for tor calculating Ib in relation to R2? What do I need to read to understand the basics of this (and not going all down to quantum level and holes etc).
Thanks