Back to "How a JFET Works"
About this Animation
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Using the Animation
Start by clicking and dragging up either of the handles on the blue voltage sliders. This applies appropriate voltages to the JFET. Watch the "What´s Happening" box for information about the transistor´s operation as you adjust the VGS and VDS sliders.
The "SHOW/HIDE " icon turns on or off, labels for the various parts of the transistor as you move your mouse over it.
Try to find suitable values for VDS and VGS So that you are controlling current flow through the transistor by using just VGS.
Using just the gate-source voltage to control current flow allows us to control a relatively large drain current by using a changing voltage and practically no gate current. The advantage of a JFET is that, although it´s gain (it´s FORWARD or MUTUAL TRANSCONDUCTANCE) is not very high we are controlling current with only a FIELD EFFECT caused by the gate-source voltage. When you have found a suitable operating condition for the transistor compare the voltages you have chosen with the graph of the output characteristice in Figure 3.1.17a on the "How a JFET Works" page.
Updated 18th August 2007