Enclosure not stated · 3 knobs
Maestro OB-1 Octave Box
Based on the Maestro OB-1 Octave Box· 1 other board clones it
- Category
- Octave / Pitch
- Controls
- Sensitivity · Octave Vol · Guitar Vol
- Build
- Vero· 28×25· 38 cuts, 17 links
- Layout
- Unverified · no build reported at Dirtbox Layouts yet
- Tags
- Maestro, Octave
From the post
Another old octave down circuit with a forest of transistors.... It also have a rare part, MFC-4040 which were a 4.pin divider/flip-flop IC. It went obsoltete in 1975 but according to several sources, NTE754 is a direct replacement. R12 and C21 is marked as "factory tailored component" in the factory schematic so these needs to be socketed and tested. And yes, there is a 1,4uF cap under Q4 but a 1,5uF will do.
Schematic
This is a board layout, a drawing of where each part goes, and the post may link the schematic it was drawn from. Open the layout at Dirtbox Layouts. No KiCad fragment has been drawn for this circuit yet.
Parts list 42 rows
Report a wrong parseGot parts in a drawer? See what you can build with them.
Check before you build · 2 values the reader of this layout was not sure of
- Electrolytic at column 19, rows H-I reads '1,4uF': printed clearly, unusual value (its lower edge overlaps the 22K next to it)
- 500pF at column 7, rows O-Q: printed clearly, unusual value
| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 21 | ||||
| ×7 | 10K | 10k | read from the layout by eye | |
| ×2 | 68K | 68k | read from the layout by eye | |
| ×2 | 680K | 680k | read from the layout by eye | |
| ×3 | 1M | 1M | read from the layout by eye | |
| ×3 | 3.3K | 3.3k | read from the layout by eye | |
| ×1 | 68Ω | 68 | read from the layout by eye | |
| ×2 | 150K | 150k | read from the layout by eye | |
| ×1 | 1.2K | 1.2k | read from the layout by eye | |
| ×1 | 1.5M | 1.5M | read from the layout by eye | |
| ×1 | 470Ω | 470 | read from the layout by eye | |
| ×2 | 100Ω | 100 | read from the layout by eye | |
| ×3 | 22K | 22k | read from the layout by eye | |
| ×1 | 120K | 120k | read from the layout by eye | |
| ×2 | 100K | 100k | read from the layout by eye | |
| ×1 | 330K | 330k | read from the layout by eye | |
| ×3 | 47K | 47k | read from the layout by eye | |
| ×2 | 220K | 220k | read from the layout by eye | |
| ×1 | 82K | 82k | read from the layout by eye | |
| ×1 | 4.7K | 4.7k | read from the layout by eye | |
| ×1 | 2.2K | 2.2k | read from the layout by eye | |
| R12 | ? | ? | LED resistor, value not given; read from the layout by eye | |
| Capacitors 14 | ||||
| ×4 | 100nF | 100n | read from the layout by eye | |
| ×1 | 68nF | 68n | read from the layout by eye | |
| ×2 | 220nF | 220n | read from the layout by eye | |
| ×1 | 22nF | 22n | read from the layout by eye | |
| ×1 | 500pF | 500p | read from the layout by eye | |
| ×4 | 10nF | 10n | read from the layout by eye | |
| ×1 | 56nF | 56n | read from the layout by eye | |
| ×1 | 330nF | 330n | read from the layout by eye | |
| ×1 | 470nF | 470n | read from the layout by eye | |
| C21 | ? | ? | value not given; legend: labelled 'factory tailored component' in factory schematic; read from the layout by eye | |
| ×3 | 1uF | 1u | electrolytic; read from the layout by eye | |
| ×1 | 1.4uF | 1.4u | electrolytic; read from the layout by eye | |
| ×1 | 10uF | 10u | electrolytic; read from the layout by eye | |
| ×1 | 220uF | 220u | electrolytic; read from the layout by eye | |
| Diodes 2 | ||||
| ×3 | 1N4148 | 1N4148 | D1-D3; read from the layout by eye | |
| D4 | 1N5817 | 1N5817 | read from the layout by eye | |
| Transistors 1 | ||||
| ×10 | 2N3904 | 2N3904 | Q1-Q10: 2N3904, 2N5088 etc. (2N3392 in original); read from the layout by eye | |
| ICs 1 | ||||
| IC1 | NTE754 | NTE754 | Motorola MFC-4040 in original; read from the layout by eye | |
| Potentiometers 3 | ||||
| Sensitivity | B10K | B10k | Potentiometer | read from the layout by eye |
| Octave Vol | A10K | A10k | Potentiometer | read from the layout by eye |
| Guitar Vol | A10K | A10k | Potentiometer | read from the layout by eye |
Other boards based on the Maestro OB-1 Octave Box
- Maestro Octave Experimentalists Anonymous