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Assembly changes:

  • Remove R5, R6
  • R105, R118, R131, R144 - change from 10.0k to 35k (+/-10% ok)
  • Install wire jumpers from pins 2-3 of JP2-JP9 (8 places).
  • Install wire jumper across JP1

Proposed PCB ECOs:

  • Add test point for current limit set (R47 etc).
  • (Add photodiode readout)
  • Add hardware "laser on" indication
  • Add low-pass filter on temp sensor inputs


Resistor values R105,107,108 set temperature window. Default values wont work. Details depend on thermistor but a good start would be to change them as follows for a modest range around 25 deg C:

Pot R47 sets current limit for laser shutdown.

Laser wont turn on unless the following are true:

  I_SHUTDOWN - backplane INTERLOCK must be at 0V (needs connector or resistor if no system controller)
  EN0/1/2/3 - must be logic ''1' from backplane (pull-down 10k on Laser/TEC)
  L_SHDN - uC output PD7 must be ''0'

Last modified 9 years ago Last modified on Nov 8, 2013, 10:17:53 AM