Polarised cap is fine. Value is from a rule of thumb that says that the impedance of the coupling capacitor should be less than a tenth of the impedance of the load. It’s value isn’t critical. But avoid the resonant frequency!
Rules of thumb are much quicker than simulation software. Sometimes you come unstuck, but not very often. That’s why they are rules-of-thumb!
By the way, 74AC125 would be a nice device to drive the coil with a square wave. When switched off, it lets the output float, instead of forcing it to 0V.
Rules of thumb are much quicker than simulation software. Sometimes you come unstuck, but not very often. That’s why they are rules-of-thumb!
By the way, 74AC125 would be a nice device to drive the coil with a square wave. When switched off, it lets the output float, instead of forcing it to 0V.