Level 3: Perfect pair
Open the level →Where it fits in the machine →
Task
Build a logical AND gate.
AND outputs 1 only when BOTH inputs are 1.
The main idea: a complex gate is a composition of simple ones: AND comes out of NAND plus NOT, because NAND is an inverted AND and one negation flips the truth back. Building gates from gates already built is the main trick of the whole course.
Related Materials
- AND — logical multiplication
Solution for self-check
Try building the circuit yourself first. The solution below is a way to check yourself if you're stuck or have already solved it.
NAND is an "inverted AND": it outputs 0 when both inputs are 1, and 1 in all other cases. If you feed NAND output into NOT, you flip the result back — getting pure AND!
Circuit: 1. Connect inputs A and B to the two NAND inputs. 2. Feed NAND output (Q) to NOT input. 3. Connect NOT output (Q) to Output.
Check: - A=0,B=0 → NAND=1 → NOT=0 ✓ - A=1,B=1 → NAND=0 → NOT=1 ✓
