typos... http://www.allaboutcircuits.com/vol_1/chpt_13/2.html If we to move the potentiometer's wiper http://www.allaboutcircuits.com/vol_1/chpt_13/5.html Equivalent circuit: Since the plates in a capacitors have some resistance http://www.allaboutcircuits.com/vol_2/chpt_1/2.html The ECG is a special-purpose oscilloscope expressly designed for medical use. http://www.allaboutcircuits.com/vol_2/chpt_1/3.html An RMS voltage produces the same heating effect as a the same DC voltage error.... http://www.allaboutcircuits.com/vol_2/chpt_1/2.html#02277.png This picture shows that an octive covers 7 keys.... but down below it says, "As you can see, one octave is equal to eight white keys' worth of distance on a piano keyboard." P.s. This is a great online book .... it's been very helpful so far. I also like the practical perspective.