Circuits II — power paths and outputs

Every product needs its parts fed the right voltage. The library has a power block for each situation — the trick is matching the source to what the load wants.

The common power blocks:

• Buck (step-down) — a higher voltage down to a lower one at good efficiency. The 12 V → 5 V buck handles a wall adapter or a car supply feeding 5 V electronics.
• Boost (step-up) — a lower voltage up. The 3.7 V → 5 V boost lets a single LiPo cell run 5 V parts (from BWF1).
• LDO regulator — a small, clean step-down for logic. The AMS1117 3.3 V turns 5 V into the 3.3 V an ESP32 wants.
• LiPo protection + charging — safely charges a lithium cell from USB and protects it from over-discharge. Any battery product needs this.
• Reverse-polarity protection — saves the board if someone connects the power backwards.

A quick way to reason about it: what's my source voltage, and what does each part want? If the source is higher, buck or LDO down; if lower, boost up; if it's a battery, add charging + protection. Forge assembles the chain, but now you can read it.

A microcontroller pin can blink an LED, but it can't power a motor, a 12 V strip, or a pump — those draw far more current than a pin can give. So outputs come in tiers, and the library has a block for each:

• Tiny loads, directly — a single LED, or an addressable NeoPixel (WS2812B) strip driven from one data pin.
• Switching a bigger load on/off — a low-side MOSFET switch (pin drives the gate; the MOSFET carries the real current) for a lamp, fan, or LED strip. Need electrical isolation or mains? Use an opto-isolated relay.
• Dimming / speed — a MOSFET PWM dimmer for a 12 V LED strip.
• Motors — a DC motor H-bridge (forward/reverse + speed), a servo driver (with proper decoupling, or a PCA9685 for many servos), or an A4988 for a stepper.

The rule of thumb: if it moves or it's bright, it doesn't hang off a pin — it gets a driver. Naming the load ("a 12 V strip," "a small DC motor," "a servo") tells Forge which driver block to add.

Let's make the "portable tax" from BWF1 concrete. A rechargeable beacon has to take a single LiPo cell and turn it into safe, usable power.

Send the prompt and look closely at the power blocks Forge selects: a LiPo protection + charging block (so it charges from USB and won't over-discharge), and a boost or regulator to give the electronics a clean supply.

That little stack — battery + charging + converter — is what "portable" always costs. Now you can spot it in any design.