Introduction to Systems Lab, CeNSE
Comparision of cellphone chargers
This videos demonstrates the behavior of output voltage when the charger is turned ON and OFF respectively. The analysis is performed without load that means no cellphone is connected to the charger.
Comparision of cellphone chargers part 2
This video shows the comparison between Samsung,Sony,Apple, and Icube cellphone chargers.These chargers have USB interface, here we show voltages at different pins of the USB connector for all the four chargers.
          Know your multimeters
Resistance of a standalone test resistor is measured using one multimeter, the current flown through it is measured by another multimeter and voltage drop across it is measured by a third one. Note the way multimeters measure resistance and current.
Measuring Internal Parameters of Multimeter
This video explains how a multimeter measures current and resistances. Here one multimeter is connected in ammeter mode and another in resistance mode. For lower resistances we get high current values. This video shows the variation of current for different range of resistances and vice versa.
Using Multimeter in Ammeter mode
We connect a power suppy (Agilent 3634A) to a resistor (3.3 Ohm) and measure current flow by putting three different multimeters (Fluke 287, Vartech MP9A, DT830D) simultaneously in series. And compare the measured current flow with the expected current. We point out the voltage drop across the MMs and it varies from one MM to other. We also show the result of exercise conducted for measuring internal resistance of the MMs in ammeter mode. Method of current measurement by a MM is also presented in a simplified way.