The formula to solve quadratic equations
I’ve been solving a lot of quadratic formulas lately, and I grew tired of searching for web-based tools to solve them. I was not able to format the output of the answers either, so I decided to write a Java application that I could manipulate. I knew that I wanted to have real and imaginary answers that were good to 3 decimal places. That keeps my answers to a good precision. I wanted the output to look like: -0.707 + 0.707j, -0.707 – 0.707j!
(-b+SQRT(b^2-4ac))/(2a) and (-b-SQRT(b^2-4ac))/(2a). This is a simple formula, but doing it by hand more than once is tedious. This program was written in the time I was supposed to be solving pole-zero plots for my DSP class. I was done solving these problems when I decided I wanted my own program to solve them for me.
Sept. 22, 2009 - Waiting on parts to come in can be boring so I went on a dig through my parts bin and found this LED still in its original packaging. While the packaging leaves a lot to be desired, I actually found the datasheet on RS’ website. I played with this LED and some 1k resistors on a breadboard, and now I’m going to make a night light that changes colors. The original program that I wrote lasts about 15 minutes, and it cycles through all of the colors [edit – at least I thought it would). It uses a rough PWM method that I wrote to fade in and out.
After a little math work I decided on using 20mA for all of my colors. They are rated for 30 to 50 mA depending on the color, but with this I can use the output pins on my PIC12F675. This saves a lot of transistors for another project.
Well, due to eBay difficulties, I was severely delayed in finishing this project. It seems that the person that I ordered my first blue LCD display from didn’t want to send a few folks their stuff this month. I went to check on the status of my order, and there were negative feedbacks from around the time that I placed it. So much for that. They sure were inexpensive.
Read below for history, but the final project is here!
This is an update to Infrared remote light control system. I never included the schematic, which is good because it was a great idea, but horribly implemented. Ten months ago I was only getting started with C, and now I know even more than before. I have updated the remote controller program and schematic to make it work even better. I used a sleep() function and the Watch Dog Timer to make it low power and to simplify the operation and construction. I’ll leave the old posting, but this is the best way to make the remote. I’ll disassemble the receiver and get a schematic out for that, someday.
This is a project that I finished around March 2008 which was well before the birth of http://Tech-tut.com. I read the first issue of Make magazine and saw a POV by a guy named Bunnie Huang (Make volume 1 Page 34-37, 186-189). This thing is really cool looking, but is way above a beginner’s head. Actually, this was when I started with the Picaxe. This was my first big project. Since then, most of this project has been lost, but I happened to find the program and the file containing the letters and numbers so I could copy and paste whatever words I wanted. I am including all this here. I’ll use my multimeter to make a new schematic. Nothing beats a little reverse engineering. Also, I may design a POV in C so that we can cater to the beginners and the advanced, but only time will tell. As for now, please enjoy the Tech-Tut POV.