MASSACHUSETTS INSTITUTE OF TECHNOLOGY 6 071 Introduction to Electronics Signals and Measurement Spring 2006 Laboratory 18 Introduction to BJT Exercise 1 For this exercise our first encounter with the BJT we will explore its i v characteristics with the aide of a prepared instrument The instrument is called BJT1 vi and it is available for download from the Labs section Build the circuit shown below and make the connections as indicated on the schematic RC IC ACH1 VC RB ACH4 IB VBE VCC ACH3 VBB IE ACH0 supply VCE RE supply ACH2 VE ACH0 ACH1 ACH2 ACH3 ACH4 For the transistor we are using the 2N3904 npn BJT whose pinout is C B E 22 071 6 071 Spring 2006 Chaniotakis Cory Page1 First look over the data sheet for the 2N3904 npn transistor and note the relevant operating and maximum characteristics Find and list the values of the following parameters 1 Maximum collector emitter voltage 2 Maximum collector current 3 Transistor listed as hFE 4 Base emitter saturation voltage 5 Collector emitter saturation voltage Open the instrument BJT1 vi and note that it requires you to enter the values for the resistors Rc and RB For RB use 100k and Rc 100 and RE 2k Run the instrument vary Vcc do not exceed 10 Volts the data acquisition system has been setup for the range 10V to 10V and collect data and plot IC versus VCE for three different values of VBB 5V 8V and 10V From the data estimate the value of VBB 22 071 6 071 Spring 2006 Chaniotakis Cory VC IC Page2 IC VCE 22 071 6 071 Spring 2006 Chaniotakis Cory Page3 Exercise 2 Build the circuit shown below with RC 2k and RB 100k VCC RC VI RB IC Vo IB For VI use the variable power supply supply and measure it and the voltage Vo with the oscilloscope For Vcc use 5 Volts Collect the data and plot them on the figure below Indicate the relevant parameters and regions of operation V0 VI 22 071 6 071 Spring 2006 Chaniotakis Cory Page4 Exercise 3 For extra credit and only if you have time Now let s build the flashing circuit using a BJT The circuit is shown below For VI use a square wave varying between 0 and 5 Volts and observe the output VCC Rl VI RB How does this compare with the diode flasher circuit that you tested previously 22 071 6 071 Spring 2006 Chaniotakis Cory Page5
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