2N2222 VCE can go beyond 20V so this circuit should work, based on your intent. You can use PWM outputwhich ever viable RPi pin you have for GPIO12, thenboth the PWM output and the RPM input for GPIO13pins.
2N2222 VCE can go beyond 20V so this circuit should work, based on your intent. You can use PWM output for GPIO12, then PWM input for GPIO13.
2N2222 VCE can go beyond 20V so this circuit should work, based on your intent. You can use which ever viable RPi pin you have for both the PWM output and the RPM input pins.