Hi,
it is a fact, that PWM is ON OFF only. There is no inbetween.
A PWM is defined by: frequency, duty cycle, HIGH (ON) level, LOW (OFF) level.
So if you drive a solenoid with PWM it is driven ON/OFF only. --> please use a scope to show the PWM waveform to verify this.
Now it depends what you connect to the PWM signal.
* A scope shows ON / OFF voltage
* a resistor shows ON / OFF, voltage as well as current
* a capacitor will show current peaks.
* an inductive load will show ON / OFF voltage (square wave) but will smooth the current. You may see some DC current with some current ripple.
Your solenoid is an inductive load. Independent of duty cycle the voltage will show ON/OFF. In your case 0V/12V.
Only if you low pass filter the voltage (with extra circuit) you may see that the average voltage is about: 12V x duty_cycle
The solenoid current is (due to it´s inductivity) already low pass filtered. Thus the solenoid current will be about: 850mA x duty_cycle
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"Average" can be of any waveform. 6V average may come from 6V DC, from 60V ON/OFF PWM with 10% duty cycle ..and it may come from 12V with 50% duty cycle.
Average is a mathematical function... to define "average" in detail you need to specify the averaging time.
Often "averaging" is made with low pass filters. They are defined by: cutoff frequency, filter order and filter type.
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Did I read wrong or is a logic mosfet for 5v low voltage like an arduino?
Logic level means: The "drive" voltage = gate-source-voltage (V_gs) is in logic level range. Mabye 5V, for details you need to consult the datasheet.
But even a "logic level MOSFET" may have higher or lower drain-source-voltage (V_DS). This depends on circuit and needs to be within datasheet specifications.
Klaus