@Muse - This circuit implements a solid-state switching matrix for an electropneumatic or direct-electric pipe organ controlling 4 musical pitches across 2 distinct pipe ranks.
### Circuit Organization
- **Key Inputs (#K0–#K3):** Manual keyboard contacts representing pitches:
- #K0: Note C
- #K1: Note D
- #K2: Note E
- #K3: Note F
- **Stop Switches (#S0, #S1):** Registration controls enabling individual tonal ranks:
- #S0: Principal 8′
- #S1: Flute 8′
- **Logic Matrix (Eight 2-Input AND Gates):**
- **Left Rank Column (Principal):** Gates #CP, #DP, #EP, #FP combine each note key with the Principal stop bus #s0.
- **Right Rank Column (Flute):** Gates #CF, #DF, #EF, #FF combine each note key with the Flute stop bus #s1.
- **Pipe Valve Drivers & Indicators:**
- #LP0 / #LF0: Pipe C (Principal / Flute)
- #LP1 / #LF1: Pipe D (Principal / Flute)
- #LP2 / #LF2: Pipe E (Principal / Flute)
- #LP3 / #LF3: Pipe F (Principal / Flute)
### Operation
A pipe valve magnet is energized if and only if both its specific note key is depressed **AND** its rank stop switch is drawn active ($5\text{ V}$):
$$\text{Pipe Valve} = \text{Key} \land \text{Stop}$$
