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I am using below scheme for generating different voltages using transformer.

Transformer

T1 transformer generates 15V and 48V ac and then rectified by AC-DC converter to generate different DC voltages (12V_Op amp Supply, -12V_Op amp supply, 16V_Logic, 38V_Constant Current Source) for my circuitry. But transformer is generating noise which is hampering ADC circuit and variation observed in ADC.

What techniques I can ensure to eliminate noise from transformer, please someone guide.

Thanks in advance.

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  • \$\begingroup\$ What type of noise? EMI? Acoustic? \$\endgroup\$ – winny Apr 13 '17 at 6:00
  • \$\begingroup\$ @ Winny, EMI noise. \$\endgroup\$ – Electroholic Apr 13 '17 at 6:01
  • \$\begingroup\$ This is a sine-output Royer oscillator and shouldn't be a noise on its output. Can you share a scope-measurement? Is that noise audible? An off-chance it might come from switching action. \$\endgroup\$ – Rohat Kılıç Apr 13 '17 at 6:04
  • \$\begingroup\$ Unfortunately, i don't have scope to share waveforms... but noise is not audible... As you said, switching action is there for solenoid valve and relay circuitry.. Is there any precaution i can take in pcb design or any shielding can be used for noise reduction? \$\endgroup\$ – Electroholic Apr 13 '17 at 6:09
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    \$\begingroup\$ "switching action is there for solenoid valve and relay circuitry" are you sure the noise is from the transformer, and not from the inductive loads you're switching? At a minimum, I hope you have freewheel-diodes placed across those inductive loads to prevent inductive spiking back into the rest of the circuit every time one is deactivated. \$\endgroup\$ – Robherc KV5ROB Apr 13 '17 at 6:57

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