Hi all,
I'm trying to calibrate an LM335 temperature sensor using a 2kOhm resistor on the voltage divider output and a 10kOhm potentiometer on the Adj pin. I've got an audio sensor module and an IR sensor both running from the 5v pin on the arduino with the LM335 - with inputs from all 3 returning to the arduino from the appropriate pins.
I'm checking the inputs periodically using the millis() function so I'm not interrupting the main loop. I'm using the audio input as a clap sensor, so there is a threshold which I'm planning to use as a switch later in the process. I appreciate that over time the temperature sensor will warm up so I'm starting by leaving it on for 10 minutes before attempting calibration. I'm finding that once I calibrate the sensor and then make too much noise, the temperature readings become unstable. I think I'm experiencing interference from the audio circuit and I gather that if this is the case then I need to de-couple them from each other - at least that's my noob guess.
I do not have an oscilloscope. If onterference is probably the case - Can anyone suggest a formula for calculating which kind of capacitor/s may be appropriate for de-coupling the sensors from each other? And also, which would be the best way to integrate them? I'm more after the calculation for future reference than the actual capacitor values themselves, although they'd be useful if that is, in fact my issue?
Many thanks and best wishes,
Cyclic