I am trying to make a voltmeter with a 10-bit ADC. The ADC can measure only positive voltages so I have made an input stage with Operational Amplifiers.
The idea of the circuit is to transform any negative voltage to positive.
V1 is the voltage output and
V Detect is 3.3V or 0V if the input signal is negative or positive, respectively.
The input frequency will not be more than 200 KHz. Will this circuit work ok whit the TL084? Is there any special parameter I should take into account?
Also I need
V1 not to exceed 3.3V, will a zener diode work or it will cause any problems with regards to capacitance? I know ADC are very sensitive to any external capacitance because of the internal sample-hold capacitor they have.