- Analysis and Reporting -

Testing the LVPS

Carefully check each component for excessive heat.
If any component is hot to the touch, unplug the circuit and check the wiring.

Three activities are suggested below to evaluate the LVPS; a check of critical voltages, a test of voltage under load, and a current test.

  1. Measure the critical voltages with your multimeter

  2. Test the LVPS with a load Connect two #47 bulbs in series to the output of your LVPS. Use a clip lead or a switch so its easy to turn the bulbs on and off.

    Figure C7
    Test Circuit

    Choose eight voltage settings in your range of output voltages. Set the voltage before connecting the bulbs. Then record the voltage after the bulbs are connected (it will be different!). You should make a table of eight trials, each with a measurement of the voltage with no load (bulbs off) and the voltage with a load (bulbs on). Record your data in a table like the shown one below.

    Figure C8
    Table ofo voltages

    Graph your data to show how the voltage varies. Graph voltages vs. trial #, one plot of V with load and another plot of V without load)

    Measure the current through the LVPS
    A voltmeter can be made into an ammeter by attaching it across a one-ohm resistor.
    ( I = V / R , so if the resistance = 1, the voltage reading = current)

    Attach the LVPS, the bulbs, and a one-ohm resistor all in series. Use the voltmeter to set the voltage of the LVPS and also to measure the voltage drop across the one-ohm resistor.

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