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T O P I C R E V I E W
mathew086
Posted - Oct 16 2009 : 10:48:26 AM I am planning to make a capactive touch sensor. I have seen many circuits from google. But i need to know how are the components chosen and how is the circuit designed.? for example how much R or C is to be used? how is the value found?
can anyone help me?
Thanks
Mathew
1 L A T E S T R E P L I E S (Newest First)
Aaron Cake
Posted - Oct 18 2009 : 10:31:42 AM On the most basic level, circuit components are chosen based upon requirements of other components. For example, in a touch switch circuit there is likely a main FET or MOSFET that has the touch plate on it's gate. That was chosen bu looking at it's specs and picking a MOSFET of appropriate gain and current/voltage capacity. The components surrounding it (resistors, capacitors) were chosen by applying some basic formulas based on the voltage and current they will see to properly bias the MOSFET (info on that is on the datasheet). Then larger circuits are built from these basic circuit building blocks.