Look, No Wires!

My backlit film prints have been very popular since I first started selling them about 10 years ago, and from the beginning people have asked whether it would be possible to make them battery powered.  Until now, the answer has been, “Theoretically, yes, but…”  In the early days I had only large sizes, and it was not very practical to run them off batteries because getting a reasonable run time would require some very expensive batteries.  Although battery technology is always improving, it’s still fairly expensive today.  But for the smaller sizes (8×10 and 11×14), ordinary AA batteries can power them quite well.

What has prevented this from becoming a reality is that it requires a driver circuit to take the battery voltage and pump it up to a suitable level (and to regulate the brightness).  Such a circuit is not complicated or expensive, but I couldn’t see enough market to justify the development effort.  That has now changed, simply because I needed the same circuit for another project.  So beginning now, I will offer a battery option for all backlit film prints.  Actually, there are two options:  For 8×10 and 11×14 prints a set of 4 AA batteries (mounted in the back of the frame) is available as a custom option.  This is a custom option simply because I can’t have every image available in every size and type (AC or battery powered) of frame, so AC power is the default, and I will build battery-powered frames to order.  The second option is USB power.  The USB-powered frame does not have a battery holder in the frame, but instead has a USB connector that can take power from a USB host (i.e., a computer) OR (and more importantly) you can use a “power tank” device with USB output to power the backlit frame.  Powering it from a computer is perhaps silly because you are then back to having a power cord/USB cable, but power tanks are readily available in a range of capacities and physical sizes.  I am testing a fairly small one, rated at 5,000 milliamp-hours, which fits nicely in the back of the frame.  Aside from the availability of very large capacities, the big advantage to using a power tank is that they are rechargeable, so you don’t have to keep buying more batteries.  Of course, you can use rechargeable AA batteries as well – they are just a bit less convenient.

So how long will it run on a set of AA batteries?  I’m testing it now, but the theoretical run time for an 8×10 print with typical AA batteries is about 11 hours.  My hunch is that it will actually prove to be more than that, but we’ll see.  The 11×14 size uses exactly twice as much power as the 8×10, so run time would be about 5.5 hours.  For the larger sizes (16×20 and 20×24) I do not recommend using AA batteries.  There is space in the frame to put a lot of them, but when you get over 4 batteries, changing them becomes tedious, so using a single power tank is a better choice.

The battery options do add a bit to the cost, and I am setting standard pricing only for the 2 basic options on the 2 smaller frame sizes:  The AA battery option adds $20 to the price of the frame, and the USB option adds $15.  Battery options for the larger size frames will be quoted individually, but will be somewhat higher because they require 2 driver circuits (to ensure that they don’t overheat).  All battery and USB options include a small rocker switch (the little bump you see on the right side of the frame) to easily turn it on/off.

Note that although the 8×10 size normally comes with a built-in “kickstand” for desktop display, the battery option eliminates that.  This is mostly because of the way the frame is built, but also because there seems to be little incentive to go cordless in a desktop frame.


About Greg Marshall

I am a retired electronics engineer and after a few months of enjoying my leisure I began to miss doing product development. My astronomy hobby always needed new solutions to unique problems, so I decided that whenever I came up with a good solution I would try to make it available to others.

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