Lightning DetectorGoalsProject DescriptionDesign CriteriaOriginal Circuit SchematicModified Circuit SchematicPhototransistorDifferentiatorSlide 9AmplifierSlide 11MOSFETSlide 13Slide 14Future WorkDecember 11, 2002December 11, 2002 11Lightning DetectorLightning DetectorMichael BloemMichael BloemJustin WilsonJustin WilsonDecember 11, 2002December 11, 2002 22GoalsGoals•Develop knowledge of circuit theoryDevelop knowledge of circuit theory•Use Pspice/Cadence to produce a working Use Pspice/Cadence to produce a working simulationsimulation•Build a working breadboard prototypeBuild a working breadboard prototypeDecember 11, 2002December 11, 2002 33Project DescriptionProject DescriptionThe device will be used to supplement the The device will be used to supplement the functionality of my camera (Nikon N70). It functionality of my camera (Nikon N70). It will allow me to take pictures of lightning will allow me to take pictures of lightning in a variety of lighting situations.in a variety of lighting situations.December 11, 2002December 11, 2002 44Design CriteriaDesign Criteria•Circuit must detect Circuit must detect variationsvariations in light levels in light levels not just lightnot just light•Circuit must amplify the light signal enough Circuit must amplify the light signal enough to operate the MOSFET with a low to operate the MOSFET with a low resistance (Vgs>>Vt)resistance (Vgs>>Vt)•Circuit must “hold” signal long enough for Circuit must “hold” signal long enough for the camera to recognize itthe camera to recognize itDecember 11, 2002December 11, 2002 55Original Circuit SchematicOriginal Circuit SchematicDecember 11, 2002December 11, 2002 66Modified Circuit SchematicModified Circuit SchematicDecember 11, 2002December 11, 2002 77PhototransistorPhototransistor•Difficult to model in Difficult to model in CadenceCadence•Modeled with a pulse Modeled with a pulse voltage supplyvoltage supplyDecember 11, 2002December 11, 2002 88DifferentiatorDifferentiatorVOt( ) C RtVIt( )ddi t( ) CtVIt( )ddDecember 11, 2002December 11, 2002 99DifferentiatorDifferentiator Time400.0ms 400.2ms 400.4ms399.9msV(U1A:OUT) V(V1:+)-10V-5V0V5V10V Time500.0ms 500.2ms 500.4ms499.9msV(U1A:OUT) V(V1:+)-10V-5V0V5V10VDecember 11, 2002December 11, 2002 1010AmplifierAmplifierVoVI1R12R11 501VVDecember 11, 2002December 11, 2002 1111AmplifierAmplifier Time400.0ms 400.2ms 400.4ms399.9msV(D6:2) V(V1:+)-5V0V5V10V Time500.0ms 500.2ms 500.4ms499.9msV(D6:2) V(V1:+)-5V0V5V10VDecember 11, 2002December 11, 2002 1212MOSFETMOSFETFor Saturation:VGSVTVDSVGSVTFor Triode:VGSVTVDSVGSVTDecember 11, 2002December 11, 2002 1313MOSFETMOSFET Time499.9ms 500.0ms 500.1ms 500.2ms 500.3ms 500.4ms 500.5msV(M3:d)5.0V5.5V6.0VSEL>>ID(M3)-200uA0A200uAV(D7:2)-2.0V0V2.0VV(V1:+)0V5V10VDecember 11, 2002December 11, 2002 1414MOSFETMOSFET Time399.9ms 400.0ms 400.1ms 400.2ms 400.3ms 400.4ms 400.5msV(M3:d)-10V0V10VID(M3)-2.0mA0A2.0mAV(D7:2)-10V0V10VV(V1:+)0V5V10VSEL>>December 11, 2002December 11, 2002 1515Future WorkFuture Work•Test circuit in lightning stormTest circuit in lightning storm•Make modifications if neededMake modifications if needed•Build final deviceBuild final
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