Hand heater for users of electric wheelchairs. Allows the operator to maintain finger dexterity in cold weather.
The complete heater in a steel case, mounted on a wheelchair so that it blows into the region of the joystick:
Heat is generated using a series of wire-wound resistors, with a small fan blowing past the resistors. A temperature sensor allows the heater to maintain a target temperature, and the fan speed can be controlled using PWM.
The example firmware supports both WiFi and Bluetooth, so the heater can be integrated with a home automation system for control or reporting.
A CAN bus interface allows the hand heater to be integrated with other devices on the chair.
A stainless steel case can be fabricated by laser-cutting and a sheet bender. The heater can then be attached to a wheelchair frame using a mounting bracket. Commonly available Go-Pro brackets can also be used, to either attach the heater to an object or sit it on a desk for stationary use.
Outputs a total of approximately 30W of power when running with a 24Vdc power supply, as typically supplied by an electric wheelchair.
Features:
- Up to 30W maximum power output
- ESP32 microcontroller
- PWM control of fan speed and heater power
- Thermistor temperature sensor
- Local control button (mode select)
- Socket for remote control button (mode select)
- Operates from 24Vdc available from wheelchair
- Approximately 1.3A current consumption at full power
- CAN bus interface for integration with other devices and controls
Partly-assembled hand heaters, with the top covers removed:
More information is available at:
https://www.superhouse.tv/handheater
The "Hardware" directory contains the PCB design as an EAGLE project. EAGLE PCB design software is available from Autodesk free for non-commercial use.
The "Firmware" directory contains example firmware as an Arduino project.
Copyright 2017-2021 SuperHouse Automation Pty Ltd.
The hardware portion of this project is licensed under the TAPR Open Hardware License (www.tapr.org/OHL). The "license" folder within this repository contains a copy of this license in plain text format.
The software portion of this project is licensed under the Simplified BSD License. The "licence" folder within this project contains a copy of this license in plain text format.