I wish to take a 1kHz PWM signal and create a symmetrical 2.5V signal from it. I do not want to have polarisation effects altering my measurements. The frequency if that is the correct term is about 1kHz Any help would be appreciated
I want to measure water content (wetness) in plant pots. A dc signal causes polarisation about the electrodes. Using an alternating +2.5V pulse followed by a -2,5V pulse gets over this problem. Using a MCU is more practical in a greenhouse particularly as I am reluctant to "play" with mains voltages in a greenhouse with water and dampness all around.
I don't see how it can not be true. Suppose you have +2.5V feeding through a resistance to Gnd for 9 seconds, followed by -2.5V through the same resistance to Gnd for 1 second, i.e. a very slow PWM signal. Won't the ratio of the amount of charge transfered be the same as the ratio of time intervals, 9:1? Note that I'm talking about "charge" rather than "current" because while it's flowing, the current is constant. And I assume it's integrated charge that affects the electrodes chemically.
As a capacitor is incapable of passing a DC current then the " integrated charge that affects the electrodes chemically" is zero irregardless of the driving signal.
Aside: While it is possible to get a constant current to flow thru a capacitor, you need to drive it in a very special way to accomplist this, or in other words, the current in a cap is only a constant in very special circumstances. A linearly changing voltage can accomplish this.