wuchy143
Member
Hi All,
I'm interested in finding out the real life capacitance of two pads which I have shown in my attached picture. Essentially this is a capacitively sensed switch. Also in my attached picture is the metal foil which, when pressed, comes down and hovers just over the two pads on the left side of the picture. So, you start out with the switch unpressed and you get the model on the left. This is just the capacitance of the two metal half moon pads along with trace capacitance because there is an excitation signal(square wave at about 1Mhz) on one of the pads coming from the Micro. When you press down the metal foil to hover over the two metal pads this creates two capacitors in series ultimately decreasing the capacitance. This change in capacitance is sense by electronics which I probably don't need to get into at this point.
What the best way to approach this to find the capacitance of first the pads? I'd like to actually calculate than say have an excitation signal and experimentally find it. I would also like to find the equivalent capacitance of adding the metal foil into the circuit.
Any thoughts, theories, or web pages with suggested reading would help. Thanks!
I'm interested in finding out the real life capacitance of two pads which I have shown in my attached picture. Essentially this is a capacitively sensed switch. Also in my attached picture is the metal foil which, when pressed, comes down and hovers just over the two pads on the left side of the picture. So, you start out with the switch unpressed and you get the model on the left. This is just the capacitance of the two metal half moon pads along with trace capacitance because there is an excitation signal(square wave at about 1Mhz) on one of the pads coming from the Micro. When you press down the metal foil to hover over the two metal pads this creates two capacitors in series ultimately decreasing the capacitance. This change in capacitance is sense by electronics which I probably don't need to get into at this point.
What the best way to approach this to find the capacitance of first the pads? I'd like to actually calculate than say have an excitation signal and experimentally find it. I would also like to find the equivalent capacitance of adding the metal foil into the circuit.
Any thoughts, theories, or web pages with suggested reading would help. Thanks!