Electric OU: Supplement: CAPACITORS… How do they WORK ?? Part 2
Please watch Part 1 first. Capacitors… how do they WORK ?? Part 2. And just how are they useful in your everyday life… if you are an oscilloscope. Here I show several things of interest: Capacitors will block the DC component of a mixed DC + AC signal. A DC offset can be added (or subtracted) from a Function Generator’s output by using an external series battery, as detailed in Agilent publications on the use of FG offset. The 10000 pF capacitance is practically invisible to the 1.5 MHz signal from the FG: the power is transferred to the load through the cap as easily as if it were a simple 10 ohm resistor experiencing a DC voltage. The battery itself even passes the 1.5 MHz signal from the FG when the battery and FG are placed in series. The bulb (and the scope) see the total voltage of the battery and the FG’s swings when the lead is connected to the positive bus bypassing the capacitor. The bulb and the scope see ONLY the 1.5 MHz oscillating AC voltage when the series battery and FG are connected to the bulb and scope probe through the DC-blocking capacitor. The entire scope trace moves up or down with respect to its zero baseline, showing the summed voltages of the 12 volt battery and the function generator’s AC waveform when the supply is connected directly to the positive rail, and showing only the FG’s AC waveform component at 1.5 MHz when the supply is connected through the capacitor. Finally, the punch line: this is exactly how and why an oscilloscope’s AC …