Based on rail-to-rail operational amplifier IC1, this circuit's input stage forms a diodeless, precision full-wave rectifier and enables the circuit of Figure 2 to display ac- or dc-voltage measurements on a dc meter
Figure 3. Based on rail-to-rail operational amplifier IC1, this circuit's input stage forms a diodeless, precision full-wave rectifier and enables the circuit of Figure 2 to display ac- or dc-voltage measurements on a dc meter