Transistor, Gate and Half Adder Outputs

About this interactive

Three lessons build a calculator from switches. Transistors: with power on one side, a 1 at the input lets power flow through to the output (a 1); a 0 at the input stops it (a 0). Whatever the voltage, 5 volts or 120, the lesson calls power a 1. Gates: two transistors one after the other on the same line make an AND gate, since power gets through only if both are on. Two side by side make an OR gate, since either one lets power through. A NOT gate flips its input. The half adder: adding two bits gives a sum and a carry. The carry is an AND of the two inputs. The sum is the OR of the inputs, X, combined in an AND gate with NOT carry, so it is 1 when either input is 1, except when both are. Type outputs as digits. For a column, list the outputs for inputs 00, 01, 10 and 11 in that order. Anything you miss shows the answer and how to work it out.

What you'll learn

Work out a transistor switch's output from its input when power is applied to it
Work out the output column of the AND, OR and NOT gates, and of transistors wired in a row or side by side
Work out the carry and sum outputs of a half adder, and the inner wires that produce them

Aligned to

CompTIA Tech+

4.2 Given a scenario, use programming organizational techniques and interpret logic.

1.3 Illustrate the basics of computing and processing.

Key terms

Transistor: A microscopic electronic switch found in microprocessors that represents a binary one (on) or zero (off) using electrical voltage.
Logic Gate: A basic electronic circuit that performs a Boolean operation on one or more binary inputs to produce a single binary output.
Truth Table: A table that lists all possible input combinations for a logic gate and their corresponding output values.
Half Adder: A combinational circuit built from AND and OR/NOT gates that adds two single-bit binary numbers and produces a Sum output and a Carry output.
Carry Output: The overflow bit produced by a half adder when the addition of two binary digits exceeds the value representable in a single bit, passing a 1 to the next column.

Topics

Transistors Logic Gates Truth Tables Half Adder Binary Interactive Calculation

About TechKnowSurge

TechKnowSurge builds IT and cybersecurity professionals through hands-on, concept-first training built around real understanding — not memorization. Free interactive tools, structured programs, and 25+ years of real-world experience, all in one place.

Explore free tools and programs →