Lab 9 RS

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Lab 9: Diode Circuits

Clipping Circuit

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

TF EIM Lab9.png

2.) Use a sine wave generator to drive the circuit so Vin=V0cos(2πνt) where V0=0.1 V and ν = 1kHz. (20 pnts)

3.)Based on your observations using a oscilloscope, sketch the voltages Vin and Vout as a function of time.

4.)Do another sketch forV0 = 1.0 V and another for 10.0 V (DONT LET ANY SMOKE OUT!). (20 pnts)

Differentiating Circuit with clipping

1) Construct the circuit below. TF EIM Lab9a.png

2) Select R1 and R2 such that the current from the +5V DC source is less than 1.0 mA and the DC voltage at Vout is 3 V when there is no input pulse.


Because we want to keep the current below 1 mA and using I=VR1+R21 mA. Solving this inequality we get the first condition for R1 and R2

 [math]1)\ \ R_1+R_2 \geq \frac{5\ V}{1\ mA} = 5\ k\Omega[/math]


Also because we want Vout=3 V and using Vout=VinR2R1+R2. Solving this equation we get the second condition R1 and R2

 [math]2)\ \ R_2 = 1.5\ R_1[/math]


I am going to use [math]R_1 = 2\ k\Omega[/math] and [math]R_2 = 3\ k\Omega[/math] which satisfy both conditions above



3) Select a capacitor (C) and a pulse width τ to form a differentiating circuit for the pulse from the signal generator. Hint: R12Cτ.


Taking (R1+R2)=5 kΩ and Cout=1.255 μF RC=6.28 ms.

And choosing the the pulse width τ80 ms6.28 ms I will be able to make good differentiator circuit.


4) plot Vin and Vout as a function of time using your scope observations. (20 pnts)


5) Now add the diode circuit from part 1 to prevent Vout from rising above +5 V. Sketch the new circuit below.


6) plot Vin and Vout as a function of time with the diode circuit you added using your scope observations. (the diode should clip off positive spikes) (20 pnts)

Questions

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


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