There are 35 circuit schematics available. Last circuit added on Tuesday, 19 May 2015.

CircuitCategoryDate AddedOK?
Design of active filters with operational amplifiers (includes circuit and Java filter calculator)FilterJan 16, 2010
Filters for the RadioJove ReceiverFilter 
Low pass filter for subwooferFilter 
Fourth order Butterworth BPF circuit diagram and design notesFilterJun 19, 2011
Chebyshev low pass filter, rolls of at 30MHzFilterJun 19, 2011
Collection of quartz crystal ladder filter circuit diagramsFilterOct 07, 2009
45 to 90Hz hum filter circuit diagramFilterSep 13, 2006
1KHz 4th order Butterworth filter using LT1367 quad operational amplifierFilterJul 03, 2011
20KHz Butterworth active filter using Linear Technology LT1124, LT1355 or LT1169FilterMay 25, 2012
'A' Weighting Filter For Audio MeasurementsFilterSep 13, 2006
Multiple Feedback Bandpass FilterFilterNov 01, 2002
Active bandpass filter with TDA2320AFilter 
Higher Order Analog Butterworth Filter Designs, includes on-line filter calculatorFilterJan 16, 2010
4th Order Butterworth filter schematic and calculatorFilterJan 16, 2010
Sallen-Key Low Pass Filter Calculator (handles Butterworth filters, Bessel filters and Chebychev)FilterJan 16, 2010
3KHz low-pass filter plus audio amp (PDF)FilterJan 26, 2001
Series Notch Fliter Designer / Calculator (displays circuit diagram after calculation)FilterJan 16, 2010
Analog Filters for Data Conversion (ADC filter)FilterJan 16, 2010
RC Low-Pass Filter with Op Amp Buffer (single pole filter) with SPICE simulation filesFilterJan 17, 2011
Sallen-Key Low-Pass Filter (Double-Pole) with SPICE simulation filesFilterJan 17, 2011
Active bandpass filtersFilterNov 01, 2002
Bandpass filtersFilterNov 01, 2002
A-weighting filter from an old Ampex service manualFilterMay 07, 2010
3 KHz low pass filter plus audio amplifier circuit diagramFilterApr 14, 2010
Sallen-Key Active Butterworth High Pass Filter Calculator and circuit diagramFilterJan 16, 2010
Sallen-Key Active Butterworth Low Pass Filter Calculator and circuit diagramFilterJan 16, 2010
Discrete Component Audio-Frequency RC FiltersFilter 
440 Hertz Peaked Low Pass Audio Filter ExperimentsFilter 
Chebyshev / Butterworth filtersFilterJun 13, 2002
Biquad Active Bandpass Filter SchematicFilterNov 01, 2002
Digital signal processor (DSP) for radio communicationsFilterJun 06, 2003
29.85 MHZ bandpass filter schematicFilterNov 01, 2002
29.85 MHZ notch filter schematicFilterNov 01, 2002
Variable notch filter with both high and low pass filtersFilterSep 13, 2006
LC filter design on-line calculatorFilterJun 13, 2002