Operational Amplifier Schmitt Trigger

In this section we will use an operational amplifier to create a Schmitt Trigger. A non-ideal operational amplifier must be used because the ideal op-amp model has trouble converging when it is used as a Schmitt Trigger. Wire the circuit  

This op-amp circuit is a Schmitt Trigger with trigger points at approximately 7.5 V. A sinusoidal voltage source will be used to swing the input from +14 V to -14 V and from -14 V to +14 V a few times. The frequency of the source is 1 Hz. This low frequency is chosen to eliminate the effects of the op-amp slew rate on the Schmitt Trigger performance. If you 

This dialog box shows us all of the possible attributes available for the sinusoidal source. The attributes are displayed alphabetically so not all of the attributes we can set are displayed on the screen capture above. We would like to change the phase of the source, so scroll the spreadsheet until you see the PHASE attribute and set its value to 90  

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Click the LEFT mouse button on the lower I2U in the upper right-hand comer to close the spreadsheet. The source we have created is Vi = 14 sin(2nt + 90°). 

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Fig. 3 A scheme of the LICRM setup operating under compressive stress, 1, Laser light source 2, movable corner reflector 3, polarizer 4 and 5, photocells 6 and 7, semi-transparent mirrors 8, stationary corner reflector 9, specimen 10, support 11, puncheon 12, clock-like scale micrometer for rough controlling deformation 13, dampers 14, figured lever providing a stress constancy 15, load 16, oil damper 17, cooling unit 18, heater 19 and 20, programmable temperature regulator 21, amplifier 22, tape recorder 23, oscillograph 24, shaper of a meander (Schmitt trigger) 25, computer with the interface board imbedded...

For amplification of the probe signal a negative feedback stabilized amplifier was employed, followed by a standard Schmitt trigger circuit of the type used in electronic scalers. This unit was arranged to be tripped by each pulse and its output was used to operate an electromagnetic counter showing total flow. This counter can be geared to indicate volumetric units directly. 

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