Nearly everytime you construct a new piece of equipment you have to design some filter. It's exactly the same for me! Now there are several ways to solve this problem: to look in catalogues and handbooks, to ask a colleague, etc. The quickest way, however, is to say your computer: "I need an active low-pass filter with no more than -0.32 dB up to 3.25 kHz and with more than 22 dB attenuation at 4.06 kHz.". "And should it be Tchebychev or Butterworth ?", it replies. "Butterworth!", you answer. The schematic diagram then appears on the screen instantaneously. It would be nice, wouldn't it ? But it IS nice! This program is in your hands. Its name is FILTRY (plural for 'filter' in Czech). It's a kind of "autonavigation program" and it needs no manual. Just type the word 'filtry' and then let the program guide you. You can print out the schematic diagram - hit <PtrScr>. You can also store the picture on the disk and print out it sometime later - by using the program "ZOBRAZ" (it means 'represent
