Hi
The galvanometer shown in the photos looks like a classic D'arsonville
mirror galvanometer, sometimes called a spot galvanometer as a light beam
takes the place of a needle pointer.. It looks like it could be a torsion
suspension type with the coil and mirror suspended on a quartz thread if
there are no signs of pivots or point bearings. Not easy to tell from the
photos but I suspect there are parts missing. The cover is to prevent the
delicate suspension from being affected by air currents. A light source
placed external to the galvanometer is essential to the operation of the
instrument as is an external scale placed at a distance from the mirror.
The sensitivity is multiplied by the arc / distance. These were capable of
recording micro amp currents flowing in circuits. The sensing coils were
usually of several thousand ohms resistance, very fine wire!
On Tue, May 22, 2012 at 9:05 AM, rchadwic <spam_OUTrchadwicTakeThisOuT
att.net> wrote:
{Quote hidden}> subject=Re:[EE:] Anyone know anything about galvanometers?
> source= www.piclist.com/piclist/2012/05/22/001229a.txt?
> Up until the change to digital and DSP technology, galvanometers were used
> as the amplifying elements in seismometers. They were (are) much less
> sensitive to variations in leakage and offset currents than operational
> amplifiers, and can be made to have large gains when combined with optics,
> mirrors and a good, solid platform (vibration-free).
>
> I never had the opportunity to work with them while I was in the Air
> Force, but talked a lot with techs that did. You might find some
> application info googling under seismology or thereabouts.
>
> Bob Chadwick
> PilList Lurker
>
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