Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations TugboatEng on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Recent content by rfonboard

  1. rfonboard

    Inductor for low frquency filter

    Tnanks! I did try the air core coil used for speaker crossover. The distortion was still bad. Finally I got the idea that the distortion was caused by the 1 uF ceramic chip capacitors used in this filter. It seems that at such a low frequency the dielectric material of the caps has a high...
  2. rfonboard

    Inductor for low frquency filter

    I discussed this problem with an enginner from Coilcraft. I thought this distortion might still be caused by the saturation distortion of the inductor. It seemed that the ferrite core used for inductor would not work well at such a low frequency. I am going to try the inductor built with either...
  3. rfonboard

    Inductor for low frquency filter

    Right now, the problem is the harmonic distortion. With 1V pk-pk fundamental signal, the harmonics are way way higher than the noise floor. They suppose to be less than the noise floor.
  4. rfonboard

    Inductor for low frquency filter

    You are right. Shielding will help for 110 dB attenuation. But at this frequency it should be very easy to achieve 90 to 100 dB attenuation. It did not gete close to it and the harmonics out of the filter were much higher than the input. Talking with the inductor manufacturer, I know the...
  5. rfonboard

    Inductor for low frquency filter

    Sorry! I thought my post weren't updated.
  6. rfonboard

    Inductor for low frquency filter

    The filter is designed to filter out the harmonics of 5KHz, which are 10KHz and 15KHz. Since the harmonics of 5KHz signal from the synthesized generator are -80 dBc relative to the fundamental, through this filter, the harmonics should be -110 dBc, which should noe be observed by using a...
  7. rfonboard

    Inductor for low frquency filter

    I have tried all kinds of active filter, like Chebychev, Multi-feedback, GIC, GIC elliptic, etc. Even the distortion performances of some OP AMP can be -120 dB in data sheet, once built in filter, the harmonic distortion can not be better than -80 dBc. Active device normally be more distortable...
  8. rfonboard

    Inductor for low frquency filter

    The filter is designed to filter out the harmonics of 5KHz, which are 10KHz and 15KHz. Since the harmonics of 5KHz signal from the synthesized generator are -80 dBc relative to the fundamental, through this filter, the harmonics should be -110 dBc, which should noe be observed by using a...
  9. rfonboard

    Inductor for low frquency filter

    I am trying to build a 5KHz passive elliptic LPF for harmonic supression. The problem was that the 1.2mH axial high current inductor caused a severe harmonic distortion. The frequecy response was exactly as it supposed to be designed. But the filter introduced higher harmonics rather than to...
See more

Part and Inventory Search

Back
Top