Basic DC Power Supply

Transcription

1 Basic DC Power Supply Equipment: 1. Analog Oscilloscope 2. Digital multimeter 3. Experimental board and connectors. Objectives: 1. To understand the basic DC power supply both half wave and full wave rectifier. 2. To understand the filter and the regulator circuit. 3. To understand the effect of load. Cautions 1. This is power supply lab. Lot of power will be delivered to Load (RL) via diode. These components will become very HOT. Don t touch them. 2. Since both scope probes have their ground clips connected to the same point (whether or not earth-referred), Student must make sure that both ground clips are connected to the same node in the test circuit. Or leave one ground clip open. Example of wrong connection of two ground clips (

2 1. Half Wave Rectifier Circuit 5W This is a BIG power resistor. Fig.1 Theory: Calculate voltage across load (R L ), average voltage, average current and peak inverse voltage. Assume = 15 V(RMS). Also draw the waveform of voltage across load (R L ) in a graph provided. V in Volt/Div Time/Div Volt/Div Time/Div

3 2. Center Tapped Full wave rectifier circuit 1k Theory: Calculate voltage across load (R L ), average voltage, average current and peak inverse. Assume = 15 V(RMS). Also draw the waveform of voltage across load (R L ) in a graph provided. V in Volt/Div Time/Div Volt/Div Time/Div

4 3. Bridge Full wave rectifier circuit (Note. In this part, only one probe will be used to measure voltage across load (R L ). Don t use another probe to measure in the same time. This will cause a short circuit) 1k Theory: Calculate voltage across load (R L ), average voltage, average current and peak inverse voltage. Assume = 15 V(RMS). Also draw the waveform of voltage across load (R L ) in a graph provided. Volt/Div Time/Div

5 4. Filter Circuit Theory: Calculate average voltage, average current, ripple factor and ripple voltage, using R L = 120Ω, C = 470μF. Assume = 15 V(RMS). Also draw the waveform of voltage across load (R L ) in a graph provided. V in Volt/Div Time/Div Volt/Div Time/Div

6 5. Regulator Circuit using Zener Diode From the circuit given below do the following Build the circuit and measure the voltage across zener diode by using oscilloscope and multimeter. - Using C= 470 μf, R S = 150 Ω(0.5 watt), R L = 0 kω (no load) V in Volt/Div Time/Div Volt/Div Time/Div - Using C= 470 μf, R S = 150 Ω(0.5 watt), R L = 1 kω V in Volt/Div Time/Div Volt/Div Time/Div

7 - Using C= 470 μf, R S = 150 Ω(0.5 watt), R L = 120 Ω(5 Watt) V in Volt/Div Time/Div Volt/Div Time/Div Lab Question: From the results of regulator circuit using zener diode in Part 5, Explain the reason why VDC is changed when RL is changed? Assignment: Determine the ripple factor of the filtered bridge rectifier with a load as indicate in this figure and show the voltage waveforms across R L. Assume the secondary voltage of transformer is 30 V(RMS) and forward voltage across diode is 0 V when diode is ON. Revised by WL 06/9/2018