POT4b

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Also see : POT4 and POT4a

revisions from POT4a

• changed reference from TL1431 to fixed voltage MAX1631
• added circuit to make REF- and REF+ approximately symmetrical about COM
• OPAMP drives REF- and REF+ is a precise voltage above REF-
• instrumentation amplifier is INA122 - which has a gain*freq product of about 200KHz.

gain and filter variations

• default gain 502x, amp cut-off 400Hz, LP2 cut-off freq of 1.6KHz, amplifier cut-off =

• B1 gain 502x, amp cut-off 400 Hz, LP2 cut-off = 497 Hz
• B2 gain 980x, amp cut-off 204 Hz, LP2 cut-off = 497 Hz
• B4 gain 4005x, amp cut-off 50 Hz, LP2 cut-off = 497 Hz

Identification

top side

bottom side

• POT4b is a green PCB with white silk screen on two sides.
• Dimensions 1.75" x 0.85"
• Two mounting holes (diameter = 0.125"), top side clearance > 0.25"
• The color of DL1,DL2 indicates the input configuration of the board

Led Indicators

• (DL1, DL2) : A pair of single LEDs indicate the present of power. These LEDs are aligned with the power input to the boards.
• DK1 : The intensity of this dual RED/GREEN LED indicates the voltage of the "position signal".

board status / history

• 4-5-06 : B5 when powered by CEB and Greddy smokes RN1 and associated PCB trace. Replaced and controlled power to board to discover that UA1 gets hot. Most likly power was applied to the input side of the board and destroyed the device.

• 3-15-05 : B3 has power application problem.

Design Files

• Media:Pot4b-sch-revb-062205.pdf
• Media:Rpot4b-pcb-top-revb-061605.pdf
• Media:Rpot4b-pcb-bot-revb-061605.pdf
• Gerber files and Tango DOS source (6-16-05)

Bill of Materials

Bill of Materials