3/3/2026 - Just Released Rev. A DataBook

I completely planned how we’re going to build our autonomous aquarium from scratch. The exact dimensions haven’t been decided yet, but I already have a rough idea of how I’m going to structure everything around them.

I accidentally knocked over a cup of water on my PC while writing this, SeaLion vibes.

It took me about two days to finish this Notion, but I genuinely believe I covered everything that actually needed to be covered.

PT-BR:
8d38ce83-3bd9-4603-ae11-4a4049196776NeedSomeFishRev.a_(otariinae)

EN-US:
690e3eea-6413-4bfc-b6b2-8d47628d4bdaNeedSomeFishRev.a(otariinae)_en

3/4/2026 - Created 3D(Fusion 360) and Launched Rev.B

I know, a full 3D in 2 days is insane, but I'm insane (or just crazy), but I did it anyway. I hope reviewers read this: I created 3D thinking that I intend to print it myself. My only desire is to get a 3D printer at the blueprint shop, which is why I didn't do it. I'll cut out the large pieces when I print it, maybe change some sizes, and try again. Silicone will be indispensable for this. I encourage you to read the Rev. B PDF. I hope it has everything you need.

Now I need to move on to the PCB and start making our Whale Shark!

This one is really interesting. It took me a while to make it:

Basically, one end is placed on the shaft of our motor and secured with silicone. The outer ends are thicker to fit the bearings embedded in the 3D model to allow rotation. It is responsible for making the rotary collector system spin and the food fall to the fish.

Sorry for this poor review of changes, I'm really tired, and I have a test tomorrow.
EN-US:
bc94b5c7-fccc-4843-9255-07d2726bed05NeedSomeFishRev.b(otariinae)_en

PT-BR:
0125515d-9364-4407-b029-74fa296e1033NeedSomeFishRev.b_(otariinae)

3/5/2026 - Something interesting, aquaponics

I've been doing some research and got some feedback on the project. I spent this afternoon researching aquaponics and how it could be interesting for my project, and honestly, it seems incredible. I had already thought about adding expansion modules to SeaLion from the beginning, and aquaponics seems quite interesting, so I decided to add a port for aquaponics as an extra, an expansion.

Aquaponics basically consists of:


With fish farming, the nutrients deposited by the fish are left behind so that this water with fish nutrients can be used for the plants. I intend to do this using a mini peristaltic pump, but for that, I will still need to work on the 3D design, create a basket where our plantation will be, and a pipe to collect filtered water from the plants and return it to the aquarium.

Diagrams of the holes in the lid:

I added the size spec in 3D as well:

3/6/2026 6 PM - Finished WhaleShark Schematic

I just finished designing our PCB schematic, and I don't think I'll be making many changes. Now I need to add the footprints for each component.

As you can see, I tried to invest heavily in safety for a V1. I'm using only one Polyfuse for the entire 12V. Ideally, there would be one per 12V port, but I'm not allowing myself that luxury. Maybe that would be something for V2 or later. I added two USB-A ports, both for connecting the Devboards. They don't transmit DATA, so the firmware must be placed on a PC to be connected only by the board.

In total, our board manages 12V, 5V, and 3.3V. The 110V is isolated and outside the board. It is transformed into 12V to enter the board.

3/6/2026 11 PM - Added Footprints and created PCB

I added all the footprints and created the PCB. It's still Rev. A of the PCB, so there may be changes, perhaps related to electrical safety or similar.

The most tedious part was organizing these LEDs.

I tried to arrange the LEDs for the PCB, but we still have some problems. To solve them, I will recreate the correct formatting for each LED in the firmware. Even if it is not in the ROW and COL order, I will recreate it in the firmware so that we can make the LED work and show the status of our aquarium.

I had to fix some DRC errors, but everything passed.

Layout done:

3D:

3/7/2026 12 AM - More a ToDo than a Devlog, beeps beeps

1. Power Routing Improvements

Priority: HIGH

Increase trace width

Current traces: ~0.20 mm

Update to:

Net	Recommended Width
Signal lines	0.20–0.25 mm
3.3V	0.30–0.40 mm
5V main rail	0.80–1.00 mm
12V rail	1.20–2.00 mm

Tasks

• [x] Identify all +12V nets
• [x] Increase trace width
• [x] Identify +5V power distribution
• [x] Increase trace width
• [x] Verify USB VBUS traces
• [x] Verify motor / load traces
• [x] Re-run DRC

---

2. Buck Converter Layout (LM2596)

Priority: CRITICAL

The switching loop must be very compact.

Components involved:

• U2 — LM2596
• L1 — Inductor
• D3 — Schottky diode
• CIN — input capacitor
• COUT — output capacitor

Tasks

• [x] Move buck section near 12V_IN
• [x] Place input capacitor directly next to LM2596 VIN
• [x] Place Schottky diode very close to SW pin
• [x] Place inductor immediately after diode
• [x] Place output capacitor close to inductor
• [x] Minimize switching loop area
• [x] Add GND vias near buck converter
• [x] Ensure thick traces for SW and VIN

---

3. Decoupling Capacitors

Priority: HIGH

Each IC must have local decoupling.

MAX7219

Required:

• 100nF ceramic
• 10µF bulk capacitor

Tasks

• [x] Move 100nF capacitor close to VCC pin
• [x] Move bulk capacitor close to MAX7219
• [x] Ensure short path to GND

AP2112 (3.3V regulator)

Tasks

• [x] Ensure input capacitor is next to VIN pin
• [x] Ensure output capacitor is next to VOUT pin
• [x] Verify ground return path is short

---

4. Voltage Divider Safety

Priority: HIGH

Current dividers are too close to 3.3V limit.

Example:

10k / 20k ≈ 3.33V when input = 5V (too close to limit)

Tasks

• [x] Replace dividers with safer ratios

Recommended examples:

Divider	Output (5V input)
10k / 18k	~3.2V
12k / 20k	~3.1V
10k / 15k	~3.0V

• [x] Verify turbidity sensor divider
• [x] Verify all analog inputs

---

5. I2C Pull-up Resistors

Priority: MEDIUM

Ensure pull-ups exist on:

• SDA
• SCL

Tasks

• [x] Add resistor SDA → 3.3V
• [x] Add resistor SCL → 3.3V
• [x] Value: 4.7kΩ

---

6. Mounting Holes

Priority: MEDIUM

Required for enclosure / aquarium mounting.

Tasks

• [x] Add 4 mounting holes
• [x] Place near PCB corners
• [x] Diameter: ~3mm(2,5mm)
• [x] Connect to GND or keep NPTH depending on design(NPTH)

---

7. Test Points

Priority: MEDIUM

Add test pads for debugging.

• [x] TP_12V
• [x] TP_5V
• [x] TP_3V3
• [x] TP_GND

---

8. USB Power Ports Labeling

Priority: LOW

These USB ports are power only.

Tasks

• [x] Add silk label: POWER ONLY
• [x] Add silk label: 5V ONLY
• [x] Verify VBUS routed correctly
• [x] Ensure polyfuse protection

---

9. 12V Distribution Safety

Priority: MEDIUM

Currently using one polyfuse for entire system.

Acceptable for Rev.A, but verify current.

Tasks

• [x] Confirm fuse current rating
• [x] Confirm trace width supports total current
• [x] Verify expected load (LED + pumps + boards)

---

10. Silk Screen Improvements

Priority: LOW

Tasks

• [x] Label polarity on all terminal blocks
• [x] Label sensor ports clearly
• [x] Label expansion connectors
• [x] Ensure text is not hidden under connectors

---

Extras

3D ToDo

• [x] Add anti-siphon system to the mini peristaltic pump in the aquaponics system

What is the siphon effect:

The siphon effect occurs when water continues to flow even without the pump being turned on, solely due to the difference in height between the reservoirs.

If the hose outlet is lower than the water level in the aquarium, gravity can cause a continuous flow.

From: sketchplanations

3/7/2026 7 AM - PCB Looks Great

Well, I basically finished our ToDo list, fixed the routing and made the necessary lines thicker, tidied up the whole layout and redid the entire track, added the capacitors, fixed the resistors, and added the Mounting Holes + Test Points.

3D:



Most/almost all notices are screen printed(seringrafia, in pt-br)

Now, I need to add the siphon break at 3D.

3/7/2026 8:09 AM - Disclaimer Siphon

I believe that in our case, since it is a mini peristaltic pump and a small hole, the risk of siphoning is low, but to eliminate any chance of it happening, I will make a small siphon-breaking hole at the top, above the water level.

3/7/2026 8:37 AM - Custom PCB

I customized the PCB and now I need to move on to creating the complete BOM, complete documentation, and complete firmware for both boards. The Whale Shark does not need firmware; it is more electrical and management-oriented, while the MAX is controlled by the board.

Updated PCB:

3D:

3/9/2026 - Organized project, finalized the BOM, and created firmware

I organized the project a bit more and published it on GitHub. I also managed to finish the entire firmware, although I still need to calibrate a few things and solve some issues that will only be possible once I have the real hardware. While doing that, I also created a diagram of the external electrical part to make things easier to understand:

The lack of a web interface or dashboard is intentional for now in V1. I consider the project, version 1.0.0, to be finished in Beta-ready. At this point, what I really need is the real hardware to continue. I also completed the full BOM and organized it into three separate CSV files with all the prices.

Regarding the size, as I mentioned before, I want to print the 3D parts myself. This gives me some flexibility to make adjustments. The current 3D design is already solid, but printing it myself will allow me to add expansion modules and ports for things like the aquaponics system. About the aquaponics part: I’ll personally cover the pump and the 3D printing for that module. Hopefully I can get the 3D printer through Blueprint itself. The pump is relatively inexpensive, and as mentioned before, it’s an expansion module. I included it on the PCB because it’s one of the project’s main differentiators.

Right now, the “correct” way to interact with SeaLion using the endpoints is through Postman, which I strongly recommend.

The height of the aquarium is determined by the acrylic panel that goes between the two 3D-printed parts. Unfortunately, acrylic tends to be expensive, so I’ll try to source it myself, even if that means using a smaller height or possibly another material as a substitute.

Repo:
https://github.com/TheusHen/Otariinae

Tag with binaries(Firmware):
https://github.com/TheusHen/Otariinae/releases/tag/v1.0.0