In case we need to seek a further reduction in the voltage regulator noise, Wenzel has kindly published their ideas for a little noise-eating circuit at the regulator output.
As it was observed that normal voltage supply is noisy and not suitable for our circuit, we plan to use a voltage regulator that will help us provide a clean supply. Referring to previous elog entries the corresponding corrections were made( polarity of electrolytic capacitors, ceramic cap in parallel to electrolytic, 3V difference between input and output of respective regulators).
Attachment 1: The Circuit Diagram of Voltage regulator
The component used Input Voltage Output Voltage
a. LM7915 -18 V -15.1 V
b. LM7815 18 V 14.86 V
c. LM317 18 V 14.96 V
Attachment 2: Output Voltage noise of regulator circuit
The noise observed using SR785 at the output of each regulator is shown. It clearly shows that LM317 manifests less noise in comparison to LM7915 and LM7815. It will be therefore a good idea to use this to provide 15V bias in our circuit.
Attachment 3: The Scripts
Find all the scripts and data used in this measurement.