Civic EG

Ok, I understand that I need a Speedohealer to turn my analog signal from the speed sensor into a digital signal to make the AP1 cluster work in my EG hatch. Can I just design and create a module that converts analog to digital without buying the $120 Speedohealer or going to a motor cycle salvage yard? It seems simple enough. I'm assuming that the digital signal is 12V. Am I making any sense? I'd like any constructive input. Thanks

honestly i think it should work just gotta get your wiring right i really dont see why it wouldnt

if it goes through the ECU, I doubt its 12v. most all sensors on our engines are 5v.

I think its a varying 0-12v. Can someone please confirm this? THanks