MarkII

 

MM_01 on gdrive (new)

MM_01 on gdrive (old)

 

Generator Measurement

 

Current Measurement Board

• This single channel AC/DC current measurement board has variable gain and a filter.  It's based on the schematic in the ACS712 datasheet.
• First Board fabbed, September 2017, r_0_2, archive on gdrive

 

• https://drive.google.com/open?id=0B27wuPBwl_tbQnJsa2F4T3pNTjA schematic
• https://drive.google.com/open?id=0B27wuPBwl_tbOTFOT2VTeERvQUU  ACS712    datasheet which schematic is based on, page 12, Application 3

• https://drive.google.com/open?id=0B27wuPBwl_tbWjJhYXE5LXk4UmM  ACS722 datasheet which is actual chip used

 

 

ACS722

• ACS722 Homepage
• ACS722 Datasheet
• Trimmer Potentiometer DigiKey Search
• ACS712 Datasheet for reference amplifier schematic
• ACS722 chip Digikey Search
• https://www.digikey.com/product-detail/en/allegro-microsystems-llc/ACS722LLCTR-05AB-T/620-1634-2-ND/4915375

 

LM321 Op-Amp

• http://www.ti.com/lit/ds/symlink/lm321.pdf

 

 

Timmer Potentiometer

• https://www.sparkfun.com/datasheets/Components/General/TSR-3386.pdf  

     TSR-3386U,EY5-10k-

     pin spacing 0.100" 

     .375" square on each side

 

Timmer Potentiometer search

* https://www.digikey.com/products/en/potentiometers-variable-resistors/trimmer-potentiometers/80

Two Candidates:

* https://www.digikey.com/product-detail/en/adafruit-industries-llc/356/1528-1997-ND/6827130

     Data sheet not correct?

 

* https://www.digikey.com/product-detail/en/sparkfun-electronics/COM-09806/1568-1616-ND/7319606

 

 

Digikey Order

• Cart for the parts needed:  http://www.digikey.com/short/qczmd9
• https://drive.google.com/open?id=0B27wuPBwl_tbOTl4Z28xZDFwSEE  BOM as ordered
• https://drive.google.com/open?id=0B27wuPBwl_tbcXhaSUUzUVE0dDA BOM as ordered from digikey

 

 

ACS712

Obsolete, less accurate version of 722.  BUT important thing is the amplifier schematic is in this datasheet, and not the ACS722 datasheet!!!!!

• Obsoleted, see ACS722
• Product Page, Allegro
• Datasheet
• Recommend filter cap size = 10 - 100 nF for 40us to 160us or 25kHz to 6kHz bandwidth
• Recommend circuit is "Application 3" with configurable gain, as observed voltages are low!
• Typical Dev Board

 

 

Other

 

 

Voltage Measurement

• R1 = 10k
• R2 = 220k
• gain = R1 / ( R1 + R2 ) = 10/230 = 0.0434782608695652

 

PCB Design

• 5 current channels
• buffered mid-point voltage
• six op-amp stages total, recommend two 4-channel ICs
• two channels for buffering voltage measurement?

 

Software

Software on mbed

 

 

References

http://www.maximintegrated.com/en/app-notes/index.mvp/id/746

http://www.ti.com/lit/an/slva385/slva385.pdf