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I've built current sink to drive wheatstone bridge. I've counted that I must reach current ~0.2mA to properly working whole measure system. Picture below present my current sink (I use MCP6001 op amp): current sink

Before constructing whole device I've simulated it in LT-spice, and simulation looked good.

Simulation

Op amp is powered ofc. MCP6001 is low power amp with Rail-to-Rail Input/Output feature. When I measure voltage on opamp output I've got zero volts... Is it possible to reach 0.2mA with this current sink based on MCP6001?

Thanks in advance!

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  • \$\begingroup\$ How are you powering your op-amp in the real world? I suspect that your device is not working because that op amp is not rail to rail... \$\endgroup\$ Jun 13, 2014 at 9:00

1 Answer 1

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Options: -

  • IC broken
  • Power pins reversed or
  • Input pins reversed
  • Resistor values are not what you think
  • 8k06 Resistor might be an inductor - check it out
  • Maybe the output pin is not connected correctly (wrong pin)
  • Output shorted to ground (solder splash/error)
  • 1.6 volt input not connected to correct place
  • 1.6 volt input shorted with solder splash
  • Power supply broken or not switched on
  • Oscilloscope/meter not connected properly
  • Meter not reading DC but AC
  • Oscilloscope/meter not working
  • The laws of physics have finally decided not to work LOL

The last one is a really scary thought.

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