Revision as of 05:01, 22 February 2011

Lab 9: Diode Circuits

Clipping Circuit

1.) Construct the circuit shown below using a silicon diode.

2.) Use a sine wave generator to drive the circuit so $V_{in} = V_0 \cos(2 \pi \nu t)$ where $V_0 = 0.1$ V and $\nu$ = 1kHz. (20 pnts)

3.)Based on your observations using a oscilloscope, sketch the voltages $V_{in}$ and $V_{out}$ as a function of time.

4.)Do another sketch for $V_0$ = 1.0 V and another for 10.0 V (DONT LET ANY SMOKE OUT!). (20 pnts)

Select $R_1$ and $R_2$ such that the current from the +5V DC source is less than 1.0 mA and the DC voltage at $V_{out}$ is 3 V when there is no input pulse.

Select a capacitor $(C)$ and a pulse width \ $tau$ to form a differentiating circuit for the pulse from the signal generator. Hint: $R_{12}C \ll \tau$ .
plot $V_{in}$ and $V_{out}$ as a function of time using your scope observations. (20 pnts)
Now add the diode circuit from part 1 to prevent $V_{out}$ from rising above +5 V. Sketch the new circuit below.
plot $V_{in}$ and $V_{out}$ as a function of time with the diode circuit you added using your scope observations. (the diode should clip off positive spikes)(20 pnts)

Explain your results in parts 1 & 2 in terms of the diode turn-on voltage. (20 pnts)

@@ Line 21: / Line 21: @@
 #Select <math>R_1</math> and <math>R_2</math> such that the current from the +5V DC source is less than 1.0 mA and the DC voltage at <math>V_{out}</math> is 3 V when there is no input pulse.
-<math>I = \frac{V}{R_1+R_2} \leq 1\ mA \rightarrow R_1+R_2 geq \frac{5\ V}{1\ mA} = 5\ k\Omega</math>
+<math>I = \frac{V}{R_1+R_2} \leq 1\ mA \rightarrow R_1+R_2 \geq \frac{5\ V}{1\ mA} = 5\ k\Omega</math>
 #Select a capacitor <math>(C)</math>and a pulse width \<math>tau</math>  to form a differentiating circuit for the pulse from the signal generator.  Hint: <math>R_{12}C \ll \tau</math>.