Transducer Amplifier Circuit

This is a design circuit for transducer amplifier circuit diagram. Here’s the figure of the circuit;

In this circuit, Pins 9 and 15 are not connected. Connect the other pins as shown. Capacitors on the supply (470uF and 0.1uF) need to be close to the IC. Keep in mind that the electrolitic capacitors have polarity (see top one). Although the amp outputs and speakers have polarity as well, it does not make a difference how you connect them, as transducers are on separate areas anyway, so do not cancel. The 1uF input coupling capacitors make a high-pass filter with the output amplifier’s 30k input resistance at about 5Hz.

Differential Instrumentation Amplifier Circuit Using Bridge Transducer

This is a design circuit for a simple differential instrumentation amplifier that has a resistive transducer (Rt).  A resistive transducer is a device whose resistance changes when a certain physical energy applied to it changes. Common examples include transducers with resistances that vary with temperature, pressure, and light shining on it. Here’s the figure of the circuit;

As in most bridge circuits, the components in this circuit's bridge network (consisting of Ra, Rb, Rc, and Rt) are chosen so that the bridge is balanced at a certain reference condition, i.e., Rc/Rb = Rt/Ra.  One way to do this is to make Ra=Rb=Rc=Rt=R at the chosen reference point. 
  
When the bridge above is balanced, Va = Vb, causing the input voltages to A3 to be equal and the output of A3 to be zero.  When the resistance of Rt changes, however, the bridge becomes unbalanced, causing a non-zero voltage Vab to appear across the inputs of A3. This, in turn, results in an output voltage Vo that is proportional to the change in resistance of Rt, i.e., Vo = (RF/R1)(ΔR/4R) Vdc where ΔR is the change in Rt's resistance. By attaching an indicating meter to the output of A3 and calibrating this accordingly, this circuit may be used to measure various physical quantities with the appropriate transducer.