DiscoverCircuits.com, has 30,000+ electronic
circuits, cross-referenced
into 500+ categories. We have searched the web to help you
find quick design ideas.
We make every effort to link to material posted by the designer.
Please let us if you would like us to link to or post your
design.
The contents & graphics of
Discovercircuits.com are copyright protected.
LINKING to Dave's circuits is permitted but DO NOT COPY any files to your WEB
SITE server
Low Pass Active Filters
3KHz LOW PASS FILTER PLUS AUDIO AMP
This circuit uses a switched capacitor filter IC from National Semiconductor to
filter signals withfrequencies higher than the 3KHz
needed for voice audio. The schematic includes an audio amplifierthat is designed to drive a standard audio head phone. The circuit is
described in more detail in thereceiver section of Dave
Johnson's Handbook of
Optical Through the AirCommunications. (this link is
off-site)
AUDIO AMP + 3KHz FILTER
This circuit is the audio amp section for a complete optical transmitter. The
circuit amplifies and filters the voice audio signals from an electret microphone.
The circuit is described in more detail in the transmitter circuit section of Dave
Johnson's Handbook of
Optical Through the Air Communications. (this link is off-site)
LOW PASS ACTIVE FILTER DESIGN COLLECTION
This is a collection of inverting and non-inverting active low pass filter circuits.
I included one, two, three, four and six pole filter circuits. You can change the
component value ratios shown, to achieve any frequency cut-off you may need. The
circuit does not specify an operational amplifier. The circuits should be used to
select the needed resistor and capacitor components for a particular frequency knee and
roll-off slope.
