522 Chapter 18 Table 18.1: PSRR Specs for Common Opamps Opamp Type 5532 LM4562 TL072 PSRR Minimum dB 80 110 70 PSRR Typical dB 100 120 100 Table 18.2: Typical Additional Supply Rails for Opamp Based Systems Supply Voltage +5 V +9 V +24 V Function Housekeeping microcontroller Relays LED bar-graph metering systems, discrete audio circuitry, relays There is however another point to ponder; if you have a number of electrolytic-sized decoupling capacitors between rail and ground, enough noise and ripple can be coupled into the non-zero ground resistance to degrade the noise floor. Intelligent placing of the decouplers can help--putting them near where the ground and supply rails come onto the