Problem: Op-amp comparator is switching before reference (threshold) voltage is reached.
As far as I can tell the comparator (non-inverting, +5v single supply, tlc2274) takes the output of low pass filter and "digitizes" it. The reference voltage on the inverting input is a voltage divider formed by a potentiometer. The reference can be adjusted from +5 to 0v. The wierd thing in this circuit is a 2200pF cap connected between the output and inverting (reference) input. I only know enough to be dangerous in regards to op-amp circuits. Does anybody have an idea what it wrong with this circuit? What is the capacitor for?
Thanks it advance,
MikeS
PS, U2B is the device reference on the schematic attached in reply #8.
As far as I can tell the comparator (non-inverting, +5v single supply, tlc2274) takes the output of low pass filter and "digitizes" it. The reference voltage on the inverting input is a voltage divider formed by a potentiometer. The reference can be adjusted from +5 to 0v. The wierd thing in this circuit is a 2200pF cap connected between the output and inverting (reference) input. I only know enough to be dangerous in regards to op-amp circuits. Does anybody have an idea what it wrong with this circuit? What is the capacitor for?
Thanks it advance,
MikeS
PS, U2B is the device reference on the schematic attached in reply #8.
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