I am making a Sallen-Key topology second order low pass filter with 10Hx cutoff frequency:
I am using the LM248 op amp. The resistor and capacitor values are specified in the drawing. However, when I input a waveform of 5Hz with 100mV amplitude(and a power supply voltage of 3V), the resulting output from my circuit is a straight line at -1 V:
The interesting observation was that when I raised my power supply to 4V, the output became a straight line at -2V, when I increased it to 5V, output became a straight line at -3V and so on. So the difference between the output voltage and power supply differed by 2.
I have checked my breadboard circuit four times and all the connections are right so I am very confused as to what is happening.