xenoflauge Posted May 30, 2006 Report Share Posted May 30, 2006 This is the receiver of a laser sensor... I can't seem to get the desired output voltage.This stage doesnt involve any modulation/demodulation yet, the problem is just with the output from the OP-AMP...Q1 is where the laser is pointed. Q2 is a compensator for ambient light...When laser is present, voltage Vb is approx. 4v... When no laser, approx. 7v, room light condition.When I hit the photo trans with laser.... The volatages Vb=4, Va=7, which would render a difference of "3V"... The gain of op-amp is R7/R1 = 10! The output should be 10(3) = 30, or limited by the supply to be 12 peek2peek.But, my output is only approx. 2 volts... what could be the problem? Quote Link to comment Share on other sites More sharing options...
audioguru Posted May 30, 2006 Report Share Posted May 30, 2006 The output voltage of a 741 opamp cannot go near its supply voltage. It should be about 10V without a load when the laser shines on Q1.If the laser is too close to Q1 then the input voltage at Va will be too low for a 741 opamp. Quote Link to comment Share on other sites More sharing options...
xenoflauge Posted May 30, 2006 Author Report Share Posted May 30, 2006 Tnx. i figured it out already.. Quote Link to comment Share on other sites More sharing options...
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