Power supplies
Start with the output rail and the conversion direction. A wall adapter, a buck module and a boost converter all say '5V out' on the label — they are not the same part.
Wall adapters (5V–24V), adjustable and fixed buck/boost/buck-boost converters (MT3608, LM2596-class), USB-C PD triggers (HUSB238), breadboard supplies, DIN-rail units and passive barrel-jack adapters.
- Wall adapters cover 5V (USB and barrel jack) up to 24V; regulated DC-DC converters include fixed-output buck modules and adjustable units like the 20W and 60W buck converters with digital displays.
- Boost and buck-boost modules handle the reverse or bidirectional case: the MT3608 boosts from sub-1V inputs, and automatic step-up/step-down modules (2.5–15V in, 3.3V/5V out) handle wide-input-range projects.
- USB-C PD trigger boards like the Adafruit HUSB238 negotiate a fixed voltage from a PD charger over I2C or jumper — useful when the project runs at 9V or 12V without a wall adapter.
- Passive adapters — 2.1mm to USB-C, barrel jack kits, MagSafe adapters and screw-terminal breakouts — convert connector format only; they carry whatever the upstream supply provides.
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Known swap options (1)
General board checks (9)
- Confirm the exact output voltage first: 3.3 V, 5 V, 9 V and 12 V are different rails.
- Check whether the part is a wall adapter, buck, boost, buck-boost, charger/power-path board, USB-C PD trigger or passive cable.
- For adjustable modules, set and measure the output before connecting the load.
- Match continuous and peak current with margin, then check heat, airflow, wiring and connector rating.
- Check polarity and connector size before plugging in a barrel adapter or wall supply.
- For USB-C PD or LiPo charger boards, verify the upstream charger, cable, battery and firmware or jumper settings.
- Check watts as well as amps: output voltage × load current, plus converter losses, must be supported by the upstream source.
- Buck converters need input headroom above the output, boost converters cannot step down, and buck-boost modules are for inputs that may cross the output rail.
- Measure adjustable converter output before connection and again under the expected load.
