This lab provides experience with diodes.
Do the following exercises. Report your results in a Word document. Submit one report per group.
Construct the following circuit, shown in Figure 1, using a 100-300 Ω load resistor and a diode. You will need an accurate measurement of the load resistor so use the bench multimeter to make the measurement. Vs is the signal generator. Set the source frequency to 1 kHz and the amplitude to 5 Volts maximum (10 volts peak-to-peak).
Figure 1. Diode test circuit
Do the following for each diode:
The XY plot above can be obtained more precisely from a set of DC measurements, as you should do next.
Figure 2. Diode test circuit (DC input).
An example of measured data are shown in Figure 3.
Figure 3. Example experimental data
Calculate the turn on voltage Von from the x-intercept and the effective diode series resistance RS from the slope ρ of the linear part of the VL vs Vin curve,where
In the example above, the linear part of the curve includes input voltages 2 V and above.
Plot the diode characteristic curve by plotting the diode current ID = VL / RL versus the diode voltage VD = VS − VL, as shown by the example below.
Figure 4. Example diode characteristic curve, ID vs. VD
Figure 5. Full-wave diode-bridge rectifier.
The XY horizontal mode converts the oscilloscope from a volts-versus-time display to a volts-versus-volts display using two input channels. Channel 1 is the X-axis input, channel 2 is the Y-axis input. You can use various transducers so the display could show strain versus displacement, flow versus pressure, volts versus current, or voltage versus frequency.
Maintained by John Loomis, last updated 5 November 2012