Self-levelling laser level

[BurningTantalum]

A friend acquired a cheapy laser level, of the type used in building work. It was new to the previous owner but had a fault in that it does not auto level.
It has a a pair of motors driving jackscrews to adjust the platform holding the rotating laser head. I cannot find any information on the net on how the electronics detects 'level', and nothing seems to be obvious.
Does anyone have any idea how this system works?
The supplied manual is a very poor example of 'Chinglish' and no calibration or set-up procedure is documented.
Regards, BT.

[H.O]

Most likely a MEMS accelerometer.

[BurningTantalum]

Thanks for that info- plenty to read on that subject!
I'm still not sure if there has been a fault from new, or we have not found the calibration procedure but the instrument doesn't seem to realign itself in 'Auto' when disturbed, but pauses and then sets off spinning again as if it had. One for a rainy day, I think...
Thanks, BT

[H.O]

Those that I've come in contact with (which, granted, aren't THAT many), both professional grade and cheap stuff from the DIY store has not had any calibration procedure described in the manual. I suppose if you take them appart you might be able to mechanicaly adjust the relationship between the leveling platform and the acceleromenter but, I have not seen any sort of "user calibration" on them.

You say it spins. When it does, is the laser actually on? That would be a bad thing if it's not actually leveled. I mean, sure it can THINK it's leveled but since the platform doesn't move the neither should the output from the accelerometer, yet it does sense when its being bumped.

Perhaps it's a manufacturing problem, putting the accelerometer on the board in the wrong orientation. Does it do anyting differently if try laying it down its side so it throws a line around vertically instead of horisontally?