Re: ATM 2 Piece Poles - and how trusses really work

["Don Clement" <clement.focuser@verizon.net>]

how would an atm actually practically measure the compression or extension
> of an aluminum pole in the range of forces involved in a typical atm
> telescope?



One method would be to attach a stain gauge to each pole. An electrical
strain gage could be as simple as a nichrome wire bonded  to each pole. (or
even measure the change in resistance of the aluminum pole itself). The
change in resistance, which is proportional to compression or extension,
could be measured with a circuit such as a Wheatstone bridge see
http://www.dwiarda.com/scientific/Bridge.html and instrumentation amplifier
with A/D , PC,  LabView software...   I am sure this isn’t the only way to
instrument a strain gage.



Don Clement

Running Springs, California

http://www.clementfocuser.com