Imported from GitHub: mattwach/portable_led_lamp · commit 4258cf8 · license GPL-3.0

Description

Contains firmware, schematics and 3D models for a LED lamp that can accept a wide range of voltages.

README

Portable LED Lamp

The page https://www.instructables.com/Portable-LED-Lamp and pdf file contain detailed build instructions, a prebuilt firmware (led_lamp.hex) file and prerendered .stl files. The rest of the instructions on this page give some additional details on the project and to explain how to build your own firmware.

If you need light but don't have an outlet available, it's nice to have an efficient light that can accept a wide variety of batteries.

This lamp can accept a wide range of voltages - between 6 and 30V. This allows it to be used with different batteries you may have lying around, including 18650 packs, RC batteries, 12V lead acid, etc.

The unit is designed to be very efficient and puts out very little heat, even at full power. A dimmer knob can be used to adjust the power consumption and light output. When "off" the lamp consumes less than 40 uA of power in its "sleep" state.

Voltage and current are monitored on a small OLED display. This allows you to estimate battery life at a given light level and make adjustments as needed for your situation.

The device has automatic shutoff when the battery voltage gets too low.

The device can autodetect the battery you are using with options for manual override.

Before we get too far, a disclaimer:

Using batteries carries a risk. Making mistakes can lead to batteries catching on fire. Sometimes batteries catch on fire even when everything is done correctly due to unknown issues during manufacturing or shipping. It is expected that you understand the risks associated with the battery you choose. Even though the hardware and software in on this page have been tested, you should not assume that your build and batteries will operate without problems. I take no responsibility for issues you may encounter while following this guide or using the provided software. Using a safety container for your battery is recommended.

Project Overview

This project contains:

• Firmware in the firmware/ directory. This firmware is intended for the ATMega328p running at 3.3v and 8Mhz. A 3.3V Arduino Pro Mini meets these specs
• A KiCad schematic and PCB layout in the schematic/ directory
• An OpenSCAD 3D printable enclosure in the 3d_print/ directory.

Schematics and Images

You'll want the free KiCAD tool to work on the schematics. The images below are screen captures from KiCAD for quick reference.

Master Board Schematic

Input Board Schematic

Building the firmware

You will need the following commandline tools available. All are free tools. Getting them will vary depending on your operating system.

• avr-gcc
• avr-objcopy
• avrdude

To build you run

make

from the firmware/ directory. To upload to a ATMega328p (pro mini) you run

make upload

Note that upload is currently not setup for windows, although it could be made to work with a few tweaks to the relatively-simple rules.mak file. The main issue is likely to be incorrect avrdude parameters. See the main avrdude documentation for for more information.

Enclosure (using OpenSCAD)

The file 3d_print/led_lamp.scad contains the 3D models.

At the bottom of the file is a section:

placed_master_pcb();
placed_input_pcb();
placed_picobuck_mount_plate(add_picobucks=true);
placed_barrel_connector();
lamp_base();
placed_led_dome(show_leds=true, barrel_connector_cutout=true);
input_holder();
placed_dimmer_knob();

You can place a * character or comment out a line with a // to omit the part. You can also prefix a line with ! to only show that part. This is useful for isolating a part for making a .stl model for printing.

Design Notes

In have design notes where I share test results for LED efficiency, component power usage and other considerations.