ORIGINAL: CGRetired
You know, the way these iPhones, Droids, and so on, you can pretty much bet on there being an App that will work as a tach. The phone is just an afterthought.... ''oh my, we should build a phone into this thing.. ''
CGr.
Funny you mention that...
I use a "wind velocity meter" app, and a Doppler shift app on my iphone.
While both are NOT highly accurate due to utilizing the built in microphone, they are "good enough" for my meager needs.
I'll bet a variation of the doppler app could become an engine tach.