Island 12V noise filter for CCD spectrometer

Schematic & Board Layout (PDF):
  • Schematic
  • PCB Silk
  • PCB Tracks
  • PCB Solder

    Express PCB Cad Files
  • Schematic
  • Board Layout

    Pictures of noise filter
  • Top view of PCB
  • PCB in enclosure
  • Bottom of PCB
  • Bottom of PCB tinned

    Scope pics of the power supply noise without any noise filter (about 1V of noise)
  • No filter, 6A draw, AC coupling, 200mV/div
  • No filter, 6A draw, DC coupling, 2V/div

    Scope pics of the noise with a 10,000uF generic electrolytic on the PS output (a quick test). Note: The noise is about 200mV (five times smaller)
  • 10,000uF electrolytic on PS output, 6A draw, AC coupling, 100mV/div
  • 10,000uF electrolytic on PS output, 6A draw, DC coupling, 2V/div

    Scope pics of the output of the noise filter with a 6A load (as shown in the schematic). Note: The noise is about 25mV (about 40 times smaller than not using any filter).
  • With filter, 6A load, AC coupling, 20mV/div
  • With filter, 6A load, DC coupling, 2V/div
  • Setup to test the noise filter at 6Av

    Scope pics of the output of noise filter with no load to light load (as shown in the schematic and pics). Note: The inductors don't do much at no current or very low current. With no load, the PS goes into a more efficient mode where it pounds the output about three times a second and causes about 70mV spikes. At 12mA the power supply looks to the switching frequency is around 66Hz and the ripple has dropped to about 35mV. At 120mA it's switching at about 570Hz with a ripple around 20mV.
  • With filter, no load, AC coupling, 20mV/div
  • With filter, 12mA load, AC coupling, 20mV/div
  • With filter, 120mA load, AC coupling, 20mV/div

    Brief description of how the filter works
  • noise filter readme.pdf