• Activity 4
Logic circuits
The understanding of sign conversion is essential for the understanding of our information-
technology world.
Computers digitally store signs which are used to complete various logical operations with
the help of the so called logic gates. The function of processors is also based on logic gates.
Devices/means:
Accessories for the simple circuit: conductor, power source, switch, bulb, computer, internet
Description of the task:
Teacher describes the logical operation, then the students individually complete some more
comlicated tasks involving logical operations for example (A or B) and (C or A). Individual
solutions are checked, errors are discussed and corrected. Having dealt with the theory
students in groups complete the and, or, and not logic gates regarding simple circuit.
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Operations are fulfilled by the logical gates
Operations are defined with the help of their truth tables
The truth table contains all the combinations of the input values as well as the output
values based on the input
The lamp only lights up when
both switches are on
The lamp lights up if any one of
the switches is on
Figure 1. Logical multiplication and summation with switches
Negation is implemented when the switch connection to the consumer is parallel. The lamp
lights up (Y true) if the K switch is off and does not light up if the switch is on.
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