This short program will use voltage measurements on the base and collector of a transistor and resistor values entered to calculate the current gain. Of course different value resistors will result in different beta values. I tried to use the smallest collector resistor possible without causing the collector voltage to rise too much. I used the USB (5V) output for the collector resistor, so make sure the collector voltage doesn't rise over 3.3V or I think bad things will happen.
main.cpp
- Committer:
- RobOnk
- Date:
- 2012-04-16
- Revision:
- 0:1dd4e19ed08e
File content as of revision 0:1dd4e19ed08e:
#include "mbed.h" AnalogIn base_voltage(p15); AnalogIn coll_voltage(p16); int base_resistor, coll_resistor; float base_current, adj_base_voltage; float coll_current, adj_coll_voltage, beta; int main() { printf ("Please enter a base resistor value\n"); scanf ("%i", &base_resistor); printf("Please enter a collector resistor value\n"); scanf ("%i", &coll_resistor); //calculate base current adj_base_voltage = (1 - base_voltage) * 3.3; //voltage across base resistor base_current = adj_base_voltage/base_resistor; //calculate collector current adj_coll_voltage = (1.515 - coll_voltage) * 3.3; //1.515 is 5V as 1 is 3.3V coll_current = adj_coll_voltage/coll_resistor; //calculate current gain beta = coll_current / base_current; printf ("Transistor beta is %f\n", beta); printf ("The voltage across Rb is %f\n", adj_base_voltage); printf ("The voltage across Rc is %f\n", adj_coll_voltage); }