Tagalog: draft — for Kate / Janet to check. Kung may servo sa mesa, hawakan habang nasa scene 3 — pilitin ang horn at pakinggan. If a servo is on the bench, hold it during scene 3 — push the horn and listen to it fight back. That sound is the whole page.
Ang servo ay hindi motor lang. Motor + gears + potentiometer + maliit na computer sa loob. A servo is not a motor. It is a motor, a gear train, a potentiometer and a tiny controller in one box — and that is why you tell it an ANGLE instead of a speed.
Ang 4 na dapat tandaan · The four that bite
1. Hindi serial ang 3-wire lead. It looks exactly like a data bus and it is not one. One wire carries a pulse whose WIDTH is the command. No addresses, no clock, no bytes (deep dive 12).
2. Sariling 5 V ang servo. Jumper sa 3.3 V. Club rule. A servo pulls amps when it moves and far more when it stalls. Feed it from the ESP32 board and the 3.3 V rail sags until the board resets — which looks exactly like a code bug and is not one.
3. 3.3 V na signal ay OK sa 5 V na servo. Only the POWER needs 5 V. The signal is read as a threshold, so a 3.3 V GPIO pulse drives a 5 V servo perfectly. Do not add a level shifter you do not need.
4. PAGSAMAHIN ang ground. Separate supply means two grounds. Join them or the pulse has no zero to be measured against, and the servo sits there twitching or dead. This is the number one cause of a "broken" servo in a club build.
| Haba ng pulso | Pulse width | Posisyon | Position |
|---|---|---|---|
| 1.0 ms | 1000 µs | 0° | One end of the travel |
| 1.5 ms | 1500 µs | 90° | Centre. The "neutral" every servo wakes up looking for. |
| 2.0 ms | 2000 µs | 180° | The other end |
| Ang 20 ms ay hindi nagbabago — ang LAPAD lang ng pulso. The 20 ms frame never changes. Only the width of the pulse inside it does. Some servos accept 0.5–2.5 ms for a wider sweep — check before you trust it, because driving past the real end stop makes the motor grind against a mechanical limit it cannot reach. | |||
| Parte | Ano ang trabaho | What it does |
|---|---|---|
| DC motor | Ang lakas | Spins fast and weakly. On its own it is useless for holding a position. |
| Gear train | Bagal pero lakas | Trades that speed for torque. Plastic gears in cheap servos, metal in the ones worth buying for a bot. |
| Output gear + horn | Ang lumalabas | The splined shaft your arm or rudder bolts to. |
| Potentiometer | Ang mata | Bolted to the output gear. As the horn turns, the pot turns, and its resistance tells the board where the horn actually is. This is deep dive 09 doing a real job. |
| Control board | Ang utak | Holds a comparator and an H-bridge (deep dive 08). Compares wanted vs actual and drives the motor either way until they match. |
1. Pulso galing sa ESP32 → boltahe na GUSTO. 2. Pot → boltahe na TOTOO. 3. Comparator: may pagkakaiba? 4. Umandar ang motor hanggang maging zero. 5. Hintay. The board never counts turns and never knows how far it has gone. It only ever asks "am I there yet?" and runs the motor in whichever direction shrinks the error. That is why a servo fights you when you push the horn — you created an error and it is doing its only job.
Ang 25 kg ay 25 kg·cm: 25 kg sa 1 cm mula sa shaft. Torque is force times distance, so the further out you bolt the load, the less it can lift. The arithmetic is just division:
| Distansya sa shaft | Kayang buhatin (25 kg·cm servo) | What this means for a bot |
|---|---|---|
| 1 cm | 25 kg | Short, stubby arm. Strong. |
| 2 cm | 12.5 kg | Twice the arm, half the lift. |
| 3 cm | 8.3 kg | |
| 5 cm | 5 kg | A long arm throws away most of the servo you paid for. |
| 10 cm | 2.5 kg | A 25 kg servo that lifts 2.5 kg. Design the arm SHORT. |
Bilis: nasa segundo kada 60°. Mas mataas ang boltahe, mas mabilis. Speed is quoted as seconds per 60° (e.g. 0.12 s/60°). More volts means faster and stronger — and hotter. Stay inside the printed range.
| Ginagawa | Kuryente | Why it matters |
|---|---|---|
| Nakahinto, walang load | Kaunti lang | Idle. Almost nothing. |
| Humahawak ng bigat | Katamtaman | Holding a position against a load still costs current. |
| Umaandar | Mataas | Moving is the normal working current. |
| STALL | Pinakamataas | Jammed, or commanded past its end stop. Current shoots up, the gears grind and the servo cooks itself. A stalled servo is a servo being destroyed. |
| Uri | Ang utos | Use it for |
|---|---|---|
| Positional servo | Anggulo (0–180°) | A rudder, a claw, a weapon arm, a steering linkage. Has the pot inside. |
| Continuous rotation | Bilis at direksyon | A drive wheel. The pot has been disconnected — 1.5 ms now means STOP, not centre, and it has no idea where it is. |
| ESC + brushless | Bilis lang | The hovercraft's lift and thrust fans. Same pulse, same lead, no position control at all, and it needs arming before it will run. |
1. Walang common ground — twitching or dead. Join the grounds. 2. Pinapakain mula sa board — the 3.3 V rail sags and the ESP32 resets mid-move. Own 5 V supply. 3. Lumabas sa end stop — commanded to 200° on a 180° servo. It stalls against a plastic wall until something gives. 4. Pinilit pabalik — back-driving the horn by hand with power off strips the gear teeth. Never use a servo horn as a handle.
Saan ito sa atin: ang rudder ng hovercraft, ang braso ng bot, at ang anumang bahagi na kailangang tumigil sa EKSAKTONG anggulo. Source: The Engineering Mindset, "Servo Motors, how do they work?" (YouTube 1WnGv-DPexc). The 3.3 V jumper rule, the 3.3 V-signal-is-fine point and the common-ground warning are ours, not the video's.