Well there I was , reaching for my tacho to get a
RPM reading on a Electric motor prop combo and .......... nothing !
Once again a dead battery .
I can tell you I was a little miffed , and on
opening the tacho and finding the button cell ( I didn't remember what
size / voltage it was ) to be 3v , I decided no more . It was time to
mod the tacho to AA batteries ( 2xAA = 3v ) ...
I started by cutting up the button cell carrier
inside the tacho , then drilling a hole for the AA battery case wires .
The case is hot glued to the tacho cover and the leads soldered to the
board on the inside , you know ! Positive to positive and negative
to negative . Then screwing the covers back and inserting some AA
And viola , it works just fine ... No
more expensive rubbish button cells , now I can use cheap rubbish AA