Buzzing sound from gauge with Voltage hooked up using PWM pin

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As PWM is a on/off voltage with a duty cycle and period you need a low pass filter to smooth the on/off signal into a smooth voltage change.

Why don't you use a standard gauge bridge circuit?

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I understood from your initial post that the resistance IS changing. Your further calculations are based on which secret details?

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I don't know what you mean by a "bridge circuit" that does not work with any voltage. Connect the bridge to Arduino Vcc to get proper readings from the ratiometric ADC.

Where one gets a resistance change in a series meter circuit it is normally supplied a regulated voltage otherwise the reading is meaningless.

Nobody seems to understand "bridge" and "ratiometic" :frowning:

DrDiettrich:
Nobody seems to understand "bridge" and "ratiometic" :frowning:

The floor is yours, take the opportunity.

Two sensible resistors can form a single voltage divider or, with the same direction of change, with one resistor each two voltage dividers which together form a bridge. See bridge sensor interface circuits.

A ratiometric ADC returns the ratio between the voltage divider or bridge supply and its tap. The highest value (1023 with a 10 bit ADC) means 100% of the supply voltage on the tap, and 0 means grounded. If the voltage divider or bridge is fed the ADC reference voltage, the result is independent of that voltage. That’s the Arduino default with AREF=Vcc.

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