sabato 14 gennaio 2012

12 db low pass lep filter

Simple 12 db low pass filter.
This filter use 2 BC547 NPN transistor and a stereo 100k pot
 for the cutoff, instead of the pot. it's possible to use 2 photo resistor.
This filter is calibrated for 5v use but also 9\12 volt for simple application.
I've develop it with Peppo at LEP lab. in Milano.
I use it in this 6 bit noise generator, video.
Val Pastel made this filter audio test listen



A small revision for the 12 db filter, this schematics is calibrated for 12 volt use.
Here you can found an eurorack version made by Danny of TAT on Etsy
Here an High Pass version of the same filter.

3 commenti:

  1. Hi Tony,
    I'm christian from italy.
    I've built your low and high pass filters and they works very fine. I would like to point out to you that, however, there is a small error in the high pass filter scheme: a polarization resistance on the last transistor is missing.
    I momentarily added a 1M resistor and the filter works. Let me know if another resistor value is better.
    Good work!

    RispondiElimina
    Risposte
    1. Can i have it on my mail please 😃 zotycheff@gmail.com

      Elimina
  2. Am a bloody beginner, but good with soldering iron, etc. good deal!
    Which of the capacitors are foil capacitors and which electrolytes? Is the 470nf a foil?

    Thank you in advance

    RispondiElimina