Hi all,
I intend to measure (small) strains on a metal plate. I have run into a problem which I can not get rid of.
Problem:
I am using a BA 660 amplifier to amplify the signal of a half-bridge setup (see setup.png) consisting of two general purpose strain gage (350 Ohm) of Vishay and two resistors of 270 Ohm. The amplified reading seems to drift and is not very stable. Additionally, it has come to my attention that the excitation voltage of the bridge is not constant and drifts initially.
Could someone please tell me:
I have attached:
Additional information:
Any help would be greatly appreciated,
Thanking you in advance,
-FlyingSwissman
--------------------------------------------------------------------------------------
Edited:
Change made: gaph-excitation-drift.jpg changed
Reason: wrong graph initially uploaded.
I intend to measure (small) strains on a metal plate. I have run into a problem which I can not get rid of.
Problem:
I am using a BA 660 amplifier to amplify the signal of a half-bridge setup (see setup.png) consisting of two general purpose strain gage (350 Ohm) of Vishay and two resistors of 270 Ohm. The amplified reading seems to drift and is not very stable. Additionally, it has come to my attention that the excitation voltage of the bridge is not constant and drifts initially.
Could someone please tell me:
- what could be causing this or a procedure to find the orgin of the problem
- how I could remove this drift/instability i.e. how I may obtain a stable readin
I have attached:
- Test setup diagram: setup.png
- Graph of initial drift of setup: graph-drift.png
- Graph of Voltage development after initial drift and compensation: graph-drift-after-offset.png
- Graph of initial excitation drift: graph-drift-excitation.jpg
Additional information:
- Power Supply (amp):
12 [V], 42 (sometimes also 39, 40 or 43) [mAmp] - Strain Gage:
Currently temporary attachment (double-sided tape), untouched/moved/altered during data acquisition
Any help would be greatly appreciated,
Thanking you in advance,
-FlyingSwissman
--------------------------------------------------------------------------------------
Edited:
Change made: gaph-excitation-drift.jpg changed
Reason: wrong graph initially uploaded.
Attachments
-
100 KB Views: 174
-
20.3 KB Views: 145
-
33.5 KB Views: 142
-
41.5 KB Views: 152
Last edited: