
Originally Posted by
Strange
In what possible sense is 5v "typical"? Typical of what?
I missed that bit, mainly due to the badly broken quoting. Transpower, please wrap your quotes in quote tags, don't just stick your responses into the quote...
Before TTL logic came along, very few things used 5V power...tube radio circuits work at voltages from millivolts to hundreds of volts. Experiments with Leyden jars often dealt with hundreds or thousands of volts. Most audio circuits work at tens of volts. Your typical PC power supply has capacitors operating at several hundred volts. Even most digital electronics these days works at 3.3V or lower. (It also generally uses MOSFET logic, with an integral part of each transistor being...guess what? A capacitor.)
More than that, the very idea that it by chance produces the same results in 5V circuits is nonsensical. Even in 5V circuits, capacitors used as a functional component of the circuit (not just something like a power supply filtering or decoupling capacitor) charge and discharge through a range of voltages below 5V, quite often less than a volt or even just a few millivolts. We couldn't possibly build modern electronic devices with such a severe misunderstanding. Or mechanical devices for that matter, considering that the same math applies to springs, air tanks, etc. Virtually nothing would work right.
Transpower, one of your basic claims is that the energy stored in a capacitor is proportional to the voltage it is charged to, right? So the difference in stored energy from full voltage to half voltage should equal that from half voltage to zero voltage, right?
Well, what is the voltage waveform of a capacitor charging or discharging at constant current? A simple linear ramp up or down. Power is current times voltage, current is constant, so the power waveform is also a simple linear ramp. Energy is total power over time, equivalent to the area under the power waveform. To illustrate, with a vertical line drawn at the point where the capacitor reaches half voltage, and a horizontal to clarify the diagram:
Code:
|\
| \
| \
|______\
| | \
| | \
|______|_____\
Two identical triangles and a rectangle. The conclusion of your claim of stored energy being proportional to voltage is that the sum of the areas of the triangle and rectangle on the left half equals the area of the triangle on the right half. The areas of the triangles alone are equal, and the rectangle has twice the area of one of the triangles, so your claim leads to the conclusion that 1 + 2 = 1. Or perhaps that rectangles have zero area, take your pick. Personally, I conclude that your theory is bunk, and that stored energy is in fact proportional to the square of voltage...
(also note that full charge isn't 5V, or 1V, or 1kV or 1µV, it's whatever you want it to be)