Hey,
I built a simple capacitive sensor consisting of a simple coil wire connected to the analog input pin of my Arduino and a high-impedance pull-down resistor.
Like this: GND -- 10M -- COIL -- A0
Now I need to amplify the signal since its not working on distances over 10 cm. I tried to use more high-impedance resistors, up to 40M, but then the input data was very interference-prone. The coil length is about 20 cm has it to be longer? I just want to catch human nearness and maybe some electromagnetic radiation of electronic devices.
So is there a simple transistor circuit to amplify the signal without creating massive interferences?
Best regards,
Dennis
EDIT: does it make any difference to use the resistor(s) as pull-up connected to +5V instead of GND?