Ece 203 electrical circuit (4)

ECE 203 - ELECTRICAL CIRCUITS PRELIMINARY ASSIGNMENT – 4 – NONLINEAR RESISTIVE CIRCUITS

Preliminary Work: 1) Read the below notes on 1N4007 diode and learn about its functioning. On your preliminary report state that you read the below notes; a) Read the notes on: http://whites.sdsmt.edu/classes/ee320/notes/320Lecture1.pdf b) Read the datasheet information “1N4007.pdf” given in moodle(UZEM) under week 7.

2) Construct the circuit given in figure1 in 5spice. Vs1 has amplitude: 3 Volts, frequency: 1KHz. Vdiff is differential voltage test point.

Figure 1: Wheatstone bridge

Study the Wheatstone bridge circuit from: http://en.wikipedia.org/wiki/Wheatstone_bridge a) Get the plot of Vdiff through Transient Analysis. Make time axis between 0 to 4miliseconds (4m) and make the max. time step=5microseconds(5u). Add this plot to your preliminary report.

b) Now change only R3 to until Vdiff is 0V (meaning its plot should be 0). Write the value of R3 for Vdiff=0V. Explain and show how this value can be found theoretically (mathematically).

3) Read the below notes on “Full Wave Bridge Rectifier�.

The Full Wave Bridge Rectifier: (tutorial taken from [1], http://www.electronics-tutorials.ws) Another type of circuit that produces the same output waveform as the full wave rectifier circuit above, is that of the Full Wave Bridge Rectifier. This type of single phase rectifier uses four individual rectifying diodes connected in a closed loop "bridge" configuration to produce the desired output. The main advantage of this bridge circuit is that it does not require a special centre tapped transformer, thereby reducing its size and cost. The single secondary winding is connected to one side of the diode bridge network and the load to the other side as shown below.

The Diode Bridge Rectifier

The four diodes labelled D1 to D4 are arranged in "series pairs" with only two diodes conducting current during each half cycle. During the positive half cycle of the supply, diodes D1 and D2 conduct in series while diodes D3 and D4 are reverse biased and the current flows through the load as shown below.

The Positive Half-cycle

During the negative half cycle of the supply, diodes D3 and D4 conduct in series, but diodes D1 and D2 switch "OFF" as they are now reverse biased. The current flowing through the load is the same direction as before.

The Negative Half-cycle

As the current flowing through the load is unidirectional, so the voltage developed across the load is also unidirectional the same as for the previous two diode full-wave rectifier, therefore the average DC voltage across the load is 0.637Vmax. However in reality, during each half cycle the current flows through two diodes instead of just one so the amplitude of the output voltage is two voltage drops ( 2 x 0.7 = 1.4V ) less than the input V MAX amplitude.

The ripple frequency is now twice the supply frequency (e.g. 100Hz for a 50Hz supply)

References [1] Tutorial on full wave rectifier, http://www.electronics-tutorials.ws/diode/diode_6.html, Accessed on November 7th, 2013.