Without giving too much detail, I have an application that requires that a load cell be used to detect the presence of an applied force and work as a switch. When a force is applied above the basal force, the circuit goes high. When the force is removed, the circuit goes low.
The load cell is based off of a 1.5 kOhm strain gauge model, and I have it in a Wheatstone bridge of 1.5 kOhm resistors with 9VDC applied. When a force is applied, the change in voltage across the nodes is, as expected, a VERY low voltage (we're talking fractional volts). So, I've been looking at using an instrumentation amplifier to up the output voltage:
http://en.wikipedia.org/wiki/Instrumentation_amplifier
However, this doesn't solve the "switching" part of the circuit. I need the load cell to be connected to some sort of a circuit that will go high (5VDC) when a load of +-10 lbs is applied to the load cell (output of something like 0.05 VDC).
How do I do this? An analog-digital converter? I'm not familiar with how they work. My background is Mechanical Engineering (some electrical courses).
Thanks for your help!!!
**Edit: Perhaps as a way of abstracting out the complications, is there a circuit that can detect a small change in voltage and throw a digital circuit high? If I used an ADC, something that could give an output of 5V for every input that is >0.05V. Make sense?
The load cell is based off of a 1.5 kOhm strain gauge model, and I have it in a Wheatstone bridge of 1.5 kOhm resistors with 9VDC applied. When a force is applied, the change in voltage across the nodes is, as expected, a VERY low voltage (we're talking fractional volts). So, I've been looking at using an instrumentation amplifier to up the output voltage:
http://en.wikipedia.org/wiki/Instrumentation_amplifier
However, this doesn't solve the "switching" part of the circuit. I need the load cell to be connected to some sort of a circuit that will go high (5VDC) when a load of +-10 lbs is applied to the load cell (output of something like 0.05 VDC).
How do I do this? An analog-digital converter? I'm not familiar with how they work. My background is Mechanical Engineering (some electrical courses).
Thanks for your help!!!
**Edit: Perhaps as a way of abstracting out the complications, is there a circuit that can detect a small change in voltage and throw a digital circuit high? If I used an ADC, something that could give an output of 5V for every input that is >0.05V. Make sense?