I have to construct suitable circuits to show the operational principles of some sensors: pH meter, sound, light and temperature. Would these count as circuits? or diagrams? (I'd say diagrams). I am finding it hard to find circuits showing how sound sensors and pH sensors work etc and the ones I do find are beyond my level such as: I under stand how the sound sensors work, such as the diaphragm microhphone (shown in first picture). Just wanting to know if I could use diagrams as circuits it would make my life easier.