The board is 1.5" x 10.4" - or if you cut each amp section into individual boards, 1.5" x 1.15"

• Sallen-Key Active Filter Dual Amplifier PCB Up Close

• Sallen-Key Active Filter Schematic

• Voltage Regulator Schematic

• Active Filter Design Guide and Texas Instruments FilterPro Software Download

• Pricing

Our RoHS compliant Sallen-Key Active Filter PCB

• Use between Data Acquisition (DAQ) inputs and sensors to remove noise and gain the voltage to utilize the full scale of your Analog to Digital Converter for the best resolution per bit
  • If you depend only on digital filtering, your analog input voltage range can be wasted on unwanted noise.  Use this Active Filter PCB to remove the noise and to gain your desired input waveform level to maximize the resolution of the Analog to Digital converter for your Data Acquisition device
• Use to make custom audio preamp crossovers
• RoHS compliant Lead-Free solder tinned pads
• High Quality board design for low frequency through high frequency applications
• Any SOIC-8 Dual Amplifier IC can be used per your application
  • Click here for a recent list of in stock amplifiers & Data Sheets
• SMT 0805 resistors & capacitors in filter circuit (0805 capacitors are easily available from Digi-Key in ceramic chip up to 22.0uF and tantalum up to 47.0uF)
• SMT 0605 (R3 & R4) resistors for gain biasing, or for unity gain, short feedback resistor pads (R3) with bus wire, or 0 ohm resistor, and leave the grounded resistor (R4) open
• SMT 1812 pads for optional 4.7uF capacitors (C5 & C6) on + and - Voltage supply inputs for noisy power supplies - similar sized capacitors as small as  1206 size will fit as well -  Click here for a 3528-21(metric) tantalum 20 Volt cap that is the best price & fit I found (Kemet PN: B45196H4475M209)
• SMT 1206 (R5 & R6) resistors for current limit/sense, or removing a channel circuit to isolate for troubleshooting
• D2Pak voltage regulators
• DO-214 or through-hole rectifier diode in regulator circuit
• Many configuration options with one PCB - each amplifier section can be configured as:
  • Low Pass Sallen-Key Butterworth, Bessel, or Chebychev filter
  • High Pass Sallen-Key Butterworth, Bessel, or Chebychev filter
  • Band Pass Sallen-Key Butterworth, Bessel, or Chebychev filter
  • with gain or unity gain
  • voltage follower
• 8 Dual Amplifier sections:
  • can be connected in series to filter/gain up to 16 amplifier stages
  • or 8 separate channels of 2 amplifier stages each
• Each Amplifier section is connected to (+) & (-) voltage supply rails with a current limiting/sensing resistor on each rail, so you can easily isolate failures
• Dual Power Supply
  • populate both (+) & (-) voltage regulators
• Single Power Supply
  • populate R6,C4,C6 and solder a short across C3 to connect V- to GND
  • populate the (+) voltage regulator and solder a short across all three pads of the (-) voltage regulator
• Flexible mounting options:
  • Each Amplifier section and Power Supply section has identical standoff holes allowing you to cut each section and stack them with size #256 metal standoffs allowing power to pass through the standoffs to each Amplifier PCB
  • you can cut and remove the unused amplifier sections of the PCB to fit your specific mounting requirements
• Thick 2 oz. copper used
• The board is 1.5" wide x 10.4" long x 0.065 " thick
   or if you cut into individual boards, each section is 1.5" wide x 1.15" long
• We can build the board to your specs

Click here for a PDF with a 1:1 scaled plot of the PCB, and a single dual-amp section, and one with the 0.090" dia (for -256 size screws) hole placement dimensions as shown here...
Make sure you set "Page Scaling:" (in the Adobe Acrobat Print window) to "None" if you want to print a life-size image

Sallen-Key Active Filter Dual Amplifier PCB Up Close          Return to Top of Page

Configured for single power supply, no filter, 2x gain 1st stage + 5x gain 2nd stage = 10x gain:

Configured for dual power supply, no filter, 2x gain 1st stage + 5x gain 2nd stage = 10x gain:

Use SMB, SMC connectors, or wire terminal blocks for the signal input and output (3.5mm spacing)

Single 5 Volt power supply & 100x gain Amp PCB for this thermal couple - In your DAQ software, [Analog Input Channel voltage - Offset voltage] / Gain.

EXAMPLE: output specs for this Amplifier are =101.849x gain & 0.0394 Volt offset... (OFFSET=short the signal input to GND & measure the signal output)

Sallen-Key Active Filter Schematic          Return to Top of Page

Click here for the Dual Amplifier section schematic

Voltage Regulator Schematic          Return to Top of Page

Click here for the Voltage Regulator section schematic

Active Filter Design Tools          Return to Top of Page

• Download this Active Filter Design Tutorial 
• Use Analog Devices' online Active Filter calculator, however, their Band-Pass schematic places C2 after C1 instead of before C1, but the component calculations are still usable. The proper schematic is in the Active Filter Design Tutorial and professional Active Filter programs such as Filter Wiz Pro which can calculate for up to 20 poles (10 amplifier stages)

Filter Wiz Pro Band-Pass schematic...

 

• Download this free Texas Instruments FilterPro software install to design your active filter.  It will calculate the resistor and capacitor values for Low Pass or High Pass as Butterworth, Bessel, Chebychev, or other custom filter types for Sallen-Key Circuit type up to 10 poles (5 Amplifier stages) with or without gain
  • Filter Pro setup .exe file
  • Filter Pro .pdf manual
  • Both files .zip archive

Pricing          Return to Top of Page

We can also sell it on

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Last modified: 06/16/08