----- Original Message ----- From: "Wan Zulhelmi Wan Ahmad Kamar" Subject: [EE] BandPass Filter > Hi, I've designed a 40khz bandpass filter. When I simulate it on > pspice, the center frequency is 40khz. However on breadboard, the > center frequency seems to be at 37khz and not at 40khz. Can this be > ignored or do i really need it at 40 khz since my ultrasonic > transducer is at 40khz. Any suggestions on what's the problem with my > circuit? Here's my circuit. Thanks in advance. Caps are only 10 or 20%, resistors 5 or 10%, seems like closer than 10% is doing well. If you want to get closer, you might try adjusting the C values a tiny bit by using a few in parallel and serial combinations. I guess at KHz you can forget about lead inductance. --McD _______________________________________________ http://www.piclist.com View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist