How do I step down a 12V pulse width modulation signal to 5V?
I would suggest using a bi-directional level shifter, they are inexpensive, apparently less then unidirectional modules and are readily available. They are not that expensive and the parts are already soldered to a PCB. There are a lot of different ones available. Try searching for&quot;level translator arduino 12V 5V&quot; There are many types and sources available for them. If you want to build it yourself consider using a MM74C914 hex inverter, it will take 25V on its inputs. Simply connect two in series.  You are correct capacitors in the circuit will definitely mess up the PWM signal. Be sure to ground the 4 remaining inputs and leave the outputs open.