XNOR GATE (EXCLUSIVE NOR)
Outputs ON when both inputs are the same (both ON or both OFF). The inverse of XOR. Used for equality comparison, combination locks, and parity circuits.
Truth Table
| Input A | Input B | Output |
|---|---|---|
| 0 (OFF) | 0 (OFF) | 1 (ON) |
| 0 (OFF) | 1 (ON) | 0 (OFF) |
| 1 (ON) | 0 (OFF) | 0 (OFF) |
| 1 (ON) | 1 (ON) | 1 (ON) |
How to Build
- 1Build an XOR gate (see XOR instructions).
- 2Add a NOT gate (block + torch) to the XOR output.
- 3The result inverts the XOR, giving XNOR behavior.
- 4Alternative: Use comparators in compare mode, output is ON when both inputs match.
Build Variants
- ▸XOR + NOT (simplest, add inverter to XOR output)
- ▸Comparator XNOR (two comparators in compare mode feeding OR)
- ▸6-torch XNOR (compact torch-only design)
- ▸Combination lock core (check if input matches key)