Hello. Ignoring my possible lack of correct terminology my question is about reading circuit diagrams in terms of understanding what they do, instead of just understanding how they are to be built. Have a look here: http://embedded-lab.com/blog/?p=1671 If you look in the middle of this article you see the following image: http://embedded-lab.com/blog/wp-content/uploads/2011/02/SignalAmplifier.jpg Now what I see is that what is happening is the diodes on the left drive the signal which is amplified across the two op amps and read by the microcontroller. My actual question is: 1. Between the diode circuit on the left and the input to the op amp you have 1 uF cap and a 68k resistor. What purpose does the resistor serve? What purpose does the capacitor serve? I've seen decoupling capacitors which, I believe, are used to quiet a noisy current before it is input to something else. The inline capacitors, I was told, sort of work to clarify a noisy current. I'm not sure what a decoupling resistor is for however I imagine that some percentage of the current will cross the 68 k resistor and so maybe it just acts as a current limiter? Thanks.