Introduction: Etched Photo and LED Text, Perfect for Valentine's Day
Last Christmas I were looking for a present for my girlfriend but I didn't want to just buy her something. It seemed to easy so I decided I was going to use my electronic experience and make her something unique. I wanted something that showed her how I feel about her.
I thought about making something with a picture but that is kind of boring. But suddenly I remembered that I had etched a photo on a PCB for a friend. That was perfect for her, I know she would like it. I played around with photoshop and finally decided for a picture that I made to black and white and then used the toner transfer method to transfer to PCB. There were some large areas that got some small holes in it so I had to fill them with a special pen. I also think that I should have swiched the black and white but it works kind of nice anyway. I finished the picture by spraying it with a transparent spray for circut boards protecting it from oxiding and getting ugly.
At the same time I found a really nice project with seven segment displays, link.
But I only had yellow displays and that would not work, so I grabbed my bag of 3 mm red LED, bought cheap from Hongkong, and started playing around with a prototype board. In the article they painted it white but I wanted the board to disappear and only show the text so I painted it black. I added a USB cable for power and put a lot of SMD resistors because that was all I had at home with 220 ohm.
All LEDs in a column is connected in series and all columns in parallel. I put as many resistors in parallel for each column as there were LEDs. But I didn't think about the heating of the resistors so the board get kind of warm and nice. I don't see this as a bug but more like a feature... :-)