For me, when I start a new project, I am not interested in directly copying an idea that is already out there. On the contrary, I find it more fulfilling to work to improve those ideas by adding new features, or by completely approaching the project in a different way while offering an alternative to what is on the market.
As a photographer, I love doing photo documentation of my projects (at the moment, I use a Canon 200D DSLR camera). Though, I am not just using photography to document my projects, I love taking photos of many other subjects as well. In case of macro photography or close-up portraits, the availability of a proper lightning source can dramatically improve the final result. For this a soft light, possibly white, not a flash is essential. The LED ring project we are presenting is not only useful for still photography but can be used for video and stop-motion animations.
Some years ago I started a similar design of a non-portable, white ring light based on a small round neon tube, but soon I abandoned the project due to the difficulty to use it in real, outdoor applications. Really it did not work well outside a photography studio. This idea came back to life when I found a very cheap, PCB LED ring on sale at a local Chinese store. It is a simple, circular design with 24 LEDs powered by either 6 or 12 VCC. The best part is it was only $4!!! Even though this little LED ring was designed for car lighting effects, its diameter and size are perfect for the photographic application I had in mind. Based on that component, the total cost of materials and components for this project will be less than $10! Very affordable indeed.
Based on the dimensions of the PCB LED ring, I designed a housing and mounting solution around it. The main portion of the housing can be 3D printed, while the front transparent cover is made out of 1.8mm thick Perspex sheet cut with a CNC router. The ring is fixed to the camera by screws on the hot shoe with a support of opaque 3mm Perspex sheet.
First of all, I designed the LED ring container; the back support is 3D-printed, while the clear front cover is cut with a CNC router from a sheet of Perspex 1,8 mm thin. Also the battery container is built in two 3D-printed parts: the battery container and the box cover hosting the control circuit.
The LED ring is holding the camera through a support fixed to the external flash socket, cut with a CNC router from 3mm Perspex laminate.
The LED ring is powered by 12 rechargeable 2100 mA/h AA batteries. The batteries, connected in series, are inside two, 6 AA battery holders. Because the LED ring needs to remain powered during the entire photo shoot, testing has been conducted to see how long the batteries will last. This testing showed they provide sufficient power for hours of continuous usage.
The easiest way to control the dimming intensity is via PWM control. For this project I decided not to use a microcontroller to control the light intensity. Instead I used a simple NE555 IC in an astable configuration. To calculate the component values needed, a few simple inputs were used to determine the proper ratings.
As shown in the schematics, the LED ring output VCC is triggered by a 4.7K potentiometer to control the intensity. An inline switch (not included in the schematics) is placed between the battery and the rest of the circuitry to turn the LED ring On/Off. The power cable connects to the battery pack through a power jack for better portability.
The resulting PCB layout has been designed to fit inside the battery pack cover box fixed with some hot glue.
The complete design consists of three main parts:
Everything easily fits into the camera bag when not in use. When you want to use it the LED ring, simply attach it to the camera and then use the long power cord (120 cm) to connect it to the battery in the camera bag. This length of cable has been more than suffieient for all the work that I have done to date.
This is a continuing effort. More to come on this project, though in the meantime, do you have any other applications for a project like this? Let us know in the comments below.