Nefarious ?
I guess I am taking money away from the button cell manufacturers ?
I dont know why , but they never last ( button cells ) for any length of time .
Except maybe in digital watches …

But every other device that uses one seem to always be flat , requiring a new battery .
Which is a little annoying !

And I do fly RC , so a Tachometer is standard kit .
Probably not something that Flashaholics might need , but I thought it an interesting mod . ( To share )

Micro Wing !