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Brownout fan: USB-C charger board, one 21700 cell, a 5 V boost module and a DC fan

Bench build · Module builds · Beginner · about 20 minutes

A rechargeable desk fan for brownouts, charged from any phone charger. A TP4056 board (USB-C, with protection) charges one 21700 cell at 1 A and protects it from over-discharge; its OUT pads feed an MT3608 boost module set to 5 V, and a switch turns the fan on. A 5000 mAh cell runs a small 5 V fan for about 4 hours. Set the MT3608 to 5.0 V with nothing on the output first: it comes set to about 12 V and would over-speed the fan.

Brownout fan: USB-C charger board, one 21700 cell, a 5 V boost module and a DC fan: the finished build running on the simulator's bench

Build it in the labGuided build, test sheet and fault finding, free in your browser.

zencircuitlab.com/l/brownout-fan

Parts list

Test procedure

Each test has an expected value and a pass range, like a factory test sheet:

  1. On battery: fan voltage
  2. Charger plugged in, fan off: charge current
  3. Switch off: fan stops

How it works

What it does: A rechargeable desk fan for brownouts, charged from any phone charger.

Build it (guided or ready-made), then run its test procedure below. Every test has an expected value and a pass range, just like a factory test sheet.

Background

The clip-on rechargeable fans sold everywhere in the Philippines are these three blocks.

More builds: module builds