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Handheld fan on one 18650 cell: USB-C TP4056, switch and a 3.7 V fan motor

Bench build · Everyday gadgets · Beginner · about 15 minutes

The pocket fan sold everywhere, charged from a phone charger. The simplest rechargeable gadget there is. A USB-C TP4056 board charges one 18650 and protects it (it cuts off at 2.5 V); the switch runs the 3.7 V fan motor straight from the cell, so the fan slows a little as the cell empties. A 2500 mAh cell runs it about 4 hours.

Handheld fan on one 18650 cell: USB-C TP4056, switch and a 3.7 V fan motor: 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/handheld-fan-18650-cell

Parts list

Test procedure

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

  1. On battery: fan current
  2. On battery: the fan spins
  3. Switch off, plugged in: charging

How it works

What it does: The pocket fan sold everywhere, charged from a 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

Handheld fans took off once 18650 cells and USB charging boards became cheap.

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