Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.
do you really want us to go give you a mathematical solution for all cases you can think of?
* DC, what range?
* AC, what frequency, amplitude
* What values of the parts?
****
some approches for DC cases: (for DC cases you may omit C1)
* when V_IN is about 5V7 --> no current flow through D1, R2, R1 --> Ib is about zero.
* when V_IN < (5V7 - D1_forward_voltage) ... (= when D1 becomes conductive) calculate: V_R1 = (5V7 - V_in - V_d1) * R1 / (R1 + R2)
* now you have some new cases:
.. * when V_R1 < V_BE_th: then ib is about zero
.. * When V_R1 > V_BE_th: then consider V_R1 is about V_BE. Calculate I_R1. calculate anew I_R2, the difference between both is Ib.
It all depends a lot on device types, temperature and so on.
you missed the brackets:
((5V7-V_in-v_d1)*R2/(R1+R2))/R2
then you may simplify it:
--> ((5V7-V_in-v_d1)*R2/(R1+R2))/R2
--> (5V7-V_in-v_d1)/(R1+R2)
(simple Ohm´s law: I = V / R)
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.