# Selecting bridge resistances for strain gauge

Discussion in 'General Electronics Chat' started by aamirali, Mar 22, 2014.

1. ### aamirali Thread Starter Member

Feb 2, 2012
415
2
I am learning quarter-bridge strain gauge.
Now how to select bridge resistance so that I can get 2mV/V or 5mV/V & so on.

My strain gauge resistance is 1000ohm.

2. ### ericgibbs Moderator

Jan 29, 2010
7,064
1,398
hi,
What are the manufacturers specifications for your 1000R strain gauge.?

ie: mVolt output at its rated excitation voltage, max load etc.??

E

3. ### Dodgydave AAC Fanatic!

Jun 22, 2012
7,723
1,280
What is the model of strain gauge?

Feb 2, 2012
415
2
5. ### t06afre AAC Fanatic!

May 11, 2009
5,936
1,226
The guage resistance is something that construction of the guage it self decide. Strain guages need an excitation voltage. So as long as the latter exitation source can deliver enough current to "drive" the guage you OK

6. ### aamirali Thread Starter Member

Feb 2, 2012
415
2
As given in datasheet strain is 1K , gauge factor = 2 & max starin = 30000E-6.

So considering gauge factor and microstrain, total %age change in resistance = 2*30000E-6 = 6%.
So change in resistance = 60ohm

1. I have to conect starin in bridge mode where I will give excitation voltage to get desired ouput like 2mV/V or 10Mv/V.
How to select that.

2. On what load I will get maximum strain for current selected strain. Datasheet says 30000 microstrain but on what kilogram of load???

3. Since I have selected strian with 1K resistance so I have kept othree three arm resistance also to 1K. So current drawn is above 4mA
But my circuit is battery operated so what should I do in this case. Increase other bridge arm resistances????
How to select arm resistances for minimum power consumption & zero output at no load.