Hey all, just found this place, looks like a sweet little forum.
anyway, I built an amplification circuit for my wheatstone bridge thats in 1/4 bridge setup. I tested the whole thing in lab with a function generator and voltage supply. I'm using a LM741 for the +/- 6V supply and a LM348N for the amplification circuit. I realize these aren't the best to be using but they're all i had at the moment.
In the lab, it worked well. amplified correctly and everything seemed kosher. Hooked it up on the car and I'm experiencing some issues. It will work....sometimes....lol....The only time i can get it to work, is if i touch my pinkie on the + terminal of the battery and my thumb on the - terminal of the battery. Then if i push on the strain gauge with my other thumb, i get a reading through our data acc system. However if i don't "bridge" the terminals with my hand I get no output.
tried higher and lower capacitor values from about 1μ all the way up to 1M and it didn't seem to have any effect.
I'm guessing that there's a ground issue...or a capacitance issue somewhere. I'm also betting to guess that my problem is in my voltage supply circuit since it worked fine in lab but not in the field.
attached is an image of the circuit. thanks!
anyway, I built an amplification circuit for my wheatstone bridge thats in 1/4 bridge setup. I tested the whole thing in lab with a function generator and voltage supply. I'm using a LM741 for the +/- 6V supply and a LM348N for the amplification circuit. I realize these aren't the best to be using but they're all i had at the moment.
In the lab, it worked well. amplified correctly and everything seemed kosher. Hooked it up on the car and I'm experiencing some issues. It will work....sometimes....lol....The only time i can get it to work, is if i touch my pinkie on the + terminal of the battery and my thumb on the - terminal of the battery. Then if i push on the strain gauge with my other thumb, i get a reading through our data acc system. However if i don't "bridge" the terminals with my hand I get no output.
tried higher and lower capacitor values from about 1μ all the way up to 1M and it didn't seem to have any effect.
I'm guessing that there's a ground issue...or a capacitance issue somewhere. I'm also betting to guess that my problem is in my voltage supply circuit since it worked fine in lab but not in the field.
attached is an image of the circuit. thanks!
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