Category Archives: Photography

DIY Mobile Solar Charger

On my recent trip to Boundary Waters in Minnesota I brought my Sony a6300 along for the ride. Months of planning and design accumulated in a week of full camera, fitbit, and GPS logging batteries.

I chose the Goal Zero Nomad 20 Solar Panel due to its 20 watt output power during peak sunlight, and it’s portability. I purposefully oversized the panel so even on cloudy days I’d still be able to get a small amount of power from it, while relying on the main battery to charge my devices until the sun would come back out.

For the battery charging I used a Mohoo 20A Charge Controller Solar Charge Regulator. Although it’s menu navigation is pretty confusing after you set it up the first time (by selecting which type of battery you’re charging) it’s plug and play from that point.

In order to get the solar panel powering the solar charger I hacked off the cigarette lighter attachment coming out of the solar panel. I was a little dismayed that hot glue was used to separate the positive and negative wires inside the adapter. Pretty bad build quality here considering the $200 price tag.

I velcro-ed the charger to the side of a 12v 7Ah lead acid battery.

The battery uses a Y adapter to attach to both the regulator and whatever I’m charging at the same time. Documentation I read online said it’s better to have the load pull from the battery then the “aux” port on the regulator. This setup allows the battery to be both charged and used at the same time. I used some left over XT90 connectors I had from my RC quadcopter.

Quick pic of the solar charger plugged into the battery but not the solar panel.

The whole setup was enclosed in a Leader Accessories 5L Dry Bag to keep things safe while on the water.
I also stored the various chargers in this.



On the charging end I spliced a Wagan 4-way 12v Automotive Splitter with another XT-90 connector. This would allow me to use stock hardware to charge the camera batteries, my fitbit, and a GPS logger for the trip.

Once on the water I used my tripod as a support for the solar panel, keeping it accurately pointed at the sun while it charged my batteries in the shade of itself.

Overall it worked excellently. It kept all my devices charged throughout the week long trip and was very easy to portage with across land. It helped me get a shot like this one!

Boats in a Row, South Temperance Lake, MN
Boats in a Row, South Temperance Lake, MN

Products used in this post:

DIY Digital Photo Frame

In previous posts I had been digitizing old family photos. This process was not simply to restore and preserve past memories but to turn into gifts for the Christmas season. I have over 6,000 new photos I’d like to put into some digital picture frames.

Pursuing online vendors left me wanting more. All sites were filled with poorly built or functioning frames. Some of the top search results on Amazon were products accused of buying all of their 5 star reviews. 800×600 resolution made me cringe as all of my scanned photos were large enough for poster size prints.

I decided I would venture a DIY route for these gifts. The tinkerer inside me knew I would be able to find a better way before Christmas. I originally looked into taking an old LCD monitor attached to a Raspberry Pi and placed into a shadow box, but the price quickly ballooned once all the pieces were tallied. I thought to myself, “Matt, why don’t you use a device that already has the LCD and computer built in together, like a tablet!”

I purchased a used Kindle Fire (first generation) and a Kindle Fire HD 7″ (second generation) and a used Nexus 7 (first generation) for some testing. I planned on stripping the device down out of it’s casing and place it into a thick picture frame instead of a larger shadow box.

The Fire has a resolution of 1024×600 at 169 dpi while the Nexus has 1280×800 at 216 dpi. Even though they were several years old they would be more than powerful enough to handle displaying simple pictures. Most of the pictures I scanned are all 4:3 either horizontal or vertical, so most of the screen wouldn’t be used when displaying an image on a widescreen display. The 8mm video I recorded would use this real estate though. The Nexus comes with a front facing camera, which I wanted to use as a proximity sensor to turn the display on and off depending on traffic walking by the frame.

To get the camera acting as a motion detector for the photo frame I had to string a few apps together. I used Motion Detector which raised “motion captured” events to Tasker which then could turn on the screen and launch the photo slideshow app. Tasker was also able to automatically get the picture frame functionality running when the tablet was powered on, making it more resilient after being powered off accidentally. Tasker also helped turn the apps off at night to save power. I used Cloud PhotoFrame EX.Net to display the slideshow. Even though it’s advertised as a cloud photo app, it worked just fine for local storage as well. I went through a few dozen slideshow apps until I settled on this one. It was the easiest to set up, had lots of display options, can play mp4 videos, and also had the ability to re-scan the photo folders for changes periodically. It has no ads and only asks to be reviewed once.

I wanted to be able to update the images on the frame automatically either over the internet or locally when visiting. I am unable to physically visit all of the recipients of the frames on a regular basis, and even when I can I don’t want to be messing around with opening up the frames and adding/removing pictures from SD cards. I decided to use Syncthing, an awesome service which uses the torrent protocol to sync files between multiple places. Syncthing allows both internet and local network connections. For recipients that don’t have wifi, I simply turn my laptop on at their house and wirelessly connect to the tablet. Syncthing finds the client running on the tablet and syncs the files between my local laptop and the tablet. Anything I add/remove from my local folder gets reflected on the frame automatically. At home I can add new pictures to a Syncthing folder, and they will be automatically pushed to any frame connected to the internet.

Getting the tablets into the picture frames required some modifications. I routed out the backsides of the frames to accommodate the size of the tablets. I centered the display inside the visible portion of the frame. I also removed the glass so the touchscreen could be used to flip to different pictures. I notched out areas around the charger port, power, and volume buttons so they could be manipulated without taking the picture out of the frame. I then used small pieces of sheet metal with screws to create “tabs” to hold the table in place. I used the back frame cover with kickstand to hold the tablet in place.

A rough fit test of the tablets inside the frames
A rough fit test of the tablets inside the frames

In the end it was a great success. It stole the show and the grandparents haven’t set it down since they got it on Christmas. I have noticed one negative downside from this. They’ve requested I scan in another box of pictures they found in the attic… 😐

Everytime they walked through the room they stopped for several minutes :)
Everytime they walked through the room they stopped for several minutes 🙂