Having been given the task to create some fun, hands-on projects for members of the public to engage in at the Library, I recently had to put my thinking cap on and see how I might be able to build a program within a tight budget. I like to create programs where attendees get to take home what they have built and learnt, and we don’t just collect the final projects and lock them away until someone asks to see them. The great part of exploring in a Makerspace is the making and then being able to share that triumph with everyone.
This latest project was to create “Light Pens,” pens that allow people to “draw with light” using digital or traditional film cameras, creating a special effect in-camera. This technique was definitely inspired by my film/cinematography days, as I have always been fascinated by how light can be manipulated through the lens to create an augmentation to the recorded image.
After working out what was needed to make these Light Pens, I did the math, and realised that the most expensive part of the process would be… the batteries! Power! Captain, I need more power! Of course, these little button cells would have to be the biggest cost of the project, as I needed at least three for every pen. If you have ever replaced a watch or small remote control battery you know that you can be up for five to ten dollars for just one! Hmmm.. what to do.
I recently inherited an old 35mm camera from my late grandfather and it used a very specialised 12 volt battery to run the 70’s style electronics for the light meter. This allowed you to get a photo within the right light index and nothing else. Luckily for me they still make this kind of battery and I ordered one online. The first thing that struck me was how small the battery was. It was tiny. In my hand, it took up half the length of my index finger. That’s small.
I know enough about electronics to know that there was no way that a small battery like that could generate 12 volts as one cell, so I made a mental note of it, and then loaded it into the camera. I hadn’t really thought about it till I was at home trying to work out an answer to get this program into budget, when I looked at the camera, and realised I might have a solution right in front of me.
Battery companies like to standardise manufacturing, it is much easier to make a few types of cells, and then reconfigure the packaging to make different type of batteries. It also makes sense to stack a number of cells together to make different voltages. This works by connecting the positive and negative terminals together. You add up the voltages until you have the voltage you need.
Batteries in parallel. Image from Battery Universe
Given the shape and size of my camera battery, I had a very strong suspicion that I might have eight 1.5 volt button batteries stacked together to make this 12 volt battery. The only way was to open the battery up and, using a scalpel, I pulled back the outer casing to find….
… eight button cells stacked on one another. These cells worked out great as they were small, and for the price of one battery I could actually get eight. I looked online and realised that these batteries are in heavy use in the US, and could be bought in a store for less that two dollars. Here in Australia, they were a little more, but in the end they were the answer I was looking for to get this project done.
It was a really easy thing to get the outer casing off, and later that week, I ordered twenty five batteries. It took me less that forty minutes to get all the batteries apart and ready. One word of caution. I was in a hurry and put all the single cells in a zip lock bag together. Not a good move. After working on the next battery, I picked up the bag to realise I had shorted out the batteries and the bag was heating up significantly as the batteries were discharging. In this case, the energy was transformed into heat. I have no doubt that if it was left long enough, it may do some damage.
To make sure that is not an issue, I taped four cells together, making sure they were insulated. Very easy and now all the batteries are ready in a little package ready to go.
Batteries all taped and ready to be stored