﻿ Work tasks - Basic characteristics of the bipolar transistor
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## Basic characteristics of the bipolar transistor

### Work tasks and measurement procedure

##### The transfer (current) characteristic
1. Measure point by point dependence of the collector current IC depending on the size-base current IB at a constant voltage between the collector and emitter UCE.

2. Plot and qualitatively compare the shape obtained according to the theory.

3. Determine the directive, which corresponds-current amplification factor β transistor in common emitter configuration, by fitting a linear regression (eg. in a spreadsheet) over the linear part of the dependence.

##### Output (collector) characteristic
1. Measure point by point dependence of the collector current IC in dependence on the voltage between collector and emitter UCE for different values-base current IB (e.g.  IB = 0 mA; 0,5 mA; 1 mA; … 2,5 mA).

2. Plot obtained according to a common chart and qualitatively compare shapes obtained with addiction theories.

3. Compare the size of the base-current IB and the collector current IC at saturation transistor. Values of the ratios compare with the current amplification factor β.

#### Measurement procedure:

1. We run a remote experiment Basic characteristics of the bipolar transistor.

##### The transfer (current) characteristic
1. We select the transfer characteristic measuring on the control panel of the remote task.

2. We set the voltage between the collector and emitter UCE to approximately 3 V by using the slider for the collector circuit.

3. We will increase mildly the size of the base-current IB by using the slider base circuit. We observe the voltage between the collector and emitter UCE. We adjust its value by using the slider for the collector circuit when UCE changes significantly from the originally settled value.

4. We save the experimental values to the table after the current stabilization of the base IB and collector IC (respecting the conditions of constant the voltage between the collector and emitter UCE).

5. We will change the size of the base-current IB and repeat the measurement (see paragraphs 4 to 5) after saving of experimental data to the table.

6. The experimental values can immediately plot on a graph (button Show graph). This option can be used for continuous control of the shape of the measured dependence. In the case of transfer characteristics is a linear dependence, the directive of this dependence corresponds to the current amplification factor for circuit with common emitter.

7. We save the experimental data to disk of PC, and stop the remote task after measuring the required data.

8. We open the resulting file in a spreadsheet (MS Excel, Oo Calc, Kingsoft Spreadsheets…).

9. We plot to the graph an dependence of the collector current IC to base current IB in the spreadsheet.

10. We interlace the obtained dependence in a spreadsheet by using linear regression (y = a.x + b) with displayed regression coefficients.

11. The value of the linear coefficient a in the regression equation is (see the expression (1)) is finding the value of the current amplification factor β.

12. We compare the obtained value of the current amplification factor β with the value of the coefficient h21 specified in the datasheet of 2N3055 transistor.

##### Output (collector) characteristic
1. We select the output characteristic measuring on the control panel of the remote task.

2. We set a fixed size of the base current IB by using the slider for base circuit. We begin with the value IB = 0 mA, then we will gradually set other values, eg.  0.5 mA; 1 mA; … 2.5 mA, in other series of measurements.

3. Now, we start to gradually adjust the voltage between the collector and emitter UCE by using the slider for the collector circuit. Collector current IC will change as a consequence (also depends on the chosen value of the base-current IB). We check that does not change the size of the base current IB! If so, we adjust the value of its size using a slider base circuit.

4. We impose experimental values to the table after the stabilization of the measured variables IB, IC and UCE (a separate table is always ready for measuring conversion and output characteristics, and it can switched between tables by selecting the measurement characteristics).

5. We change the voltage between the collector and emitter UCE) after saving of experimental data to the table, and we repeat measuring (see paragraphs 15 to 16).

6. The experimental values can immediately plot on a graph (button Show graph). This option can be used for continuous control of the shape of the measured dependence. This is a bundle of dependencies set by base current IBin case of the output characteristics. Displaying experimental values will be important until after measuring several dependencies for different values-base current IB.

7. We will change the size of the base current after measuring a dependence – interdependence IC and UCE for const. IB – and we measure the same thing again. In other words: We repeat measuring from point 14. to 18. with another base current.

8. We save the experimental data to disk of PC, and stop the remote task after measuring the required data.

9. We open the resulting file in a spreadsheet (MS Excel, Oo Calc, Kingsoft Spreadsheets…).

10. We split the experimental data for each series according to the specified base current IB in the spreadsheet. We plot in the same chart all dependencies. We create the bundle of output characteristics where the base current IB is a parameter.

11. We compare the shapes obtained dependencies plotted into a common graph with the theory.

12. We compare the size of the base current IB and the collector current IC at saturation of the transistor ("constant" part of the characteristic). We compare the values of mutual ratios of the currents with the value of the current amplification factor β obtained from the transfer characteristic.