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Neural Circuits Lab

Please download the schematic for the lab.

In groups or individually:

-Build the basic comparator circuit following the schematic. R2 controls the reference voltage while R1 supplies the input voltage. Use a voltmeter to measure the vref and set it to a desired voltage, ie. 4.0 volts. Use a voltmeter to measure the voltage on R1 and verify that the LED changes state when the reference voltage on R2 is exceeded by R1. Does it behave as you would expect?

-Build the Comparator with photocell circuit from the schematic. Use the voltmeter to measure the voltage on the photocell/resistor junction while you cover it up. Adjust the reference voltage if necessary so that when you cover the photocell the LED changes state. What is your threshold voltage?

-Create a network of 3 input photocells as in the schematic for comparator with multiple photocells and adjustable weights. Adjust the potentiometer weights and the reference voltage so that covering 2 photocells changes the state of the LED but covering 1 does not. How is this similar to the perceptron and how is it different? How could the circuit be changed to be more similar to the perceptron?

As a class:

-How could we combine the class’s circuits into one larger network? How could we make this larger network recognize a specific pattern (or could we)? And how could this circuit be modified to make it a feasible neural network?