I'm designing a circuit to detect a slight change in temperature and activate a motor. I used a Wheatstone bridge, with one leg being a 10kohm thermistor shown in schematic below. The signal is then amplified with an 741 op amp. When I read the voltage output (delta V) from the op amp it is exactly as I want it when the temperature changes, about 0.6V. When I attach the motor (0.5V threshold) as shown, it does not work and the output voltage (delta V) now reads -7.2V. What is wrong? What should I try to fix the problem?
Thanks!
Thanks!