http://elegans.uky.edu/blog Sun, 22 Nov 2009 23:36:52 +0000 http://backend.userland.com/rss092 en At the beginning of October, it was reported that eight US soldiers were killed in Nuristan province in Afghanistan. Hearing it at the time, I thought nothing in Nuristan can be worth the life of an American soldier, yet eight of them fought and died there. Afghanistan is ... http://elegans.uky.edu/blog/?p=176 Third PIC program, this one moves a hobby servo motor using a 10kΩ pot. The pot is read using the A/D converter function on the PIC. The four high bits of the value are used to control the servo to sixteen positions over its range. Two more ... http://elegans.uky.edu/blog/?p=175 Putting video clips on my blog was a bit harder than I expected. I first tried converting the .MOV files the camera writes into .avi files using ffmegX and posting them using <embed> tag code. The files showed up great on my Mac but not at all on ... http://elegans.uky.edu/blog/?p=174 Second PIC program, this one moves a hobby servo motor to one of two positions. The switch needs to be pulled up with a resistor. It has one light that is always on and a second that switches on/off when the servo moves. PIC12F683 servo motor movie: ... http://elegans.uky.edu/blog/?p=173 Got my first PIC microprocessor program running on a PIC12F683. It has one light that is always on and a second that switches on/off. PIC12F683 LED lighting movie: The assembler code: ---------------------------------------------------------------------------- ;************************************ ;written by: Jim Lund ;date: 11-09 ;version: 1.00 ;for PIC: PIC12F683 ;Memory: 2048=800h, RAM 128, EEPROM 256 ;clock frequency: ;************************************ ; PROGRAM FUNCTION: Light ... http://elegans.uky.edu/blog/?p=172 What would be required to set up an inexpensive system for hobbyists to experiment with biology? Consider PCR for example. PCR requires heat stable polymerase, primers, nucleotides, buffer. The DNA polymerase is easy to purify from E. coli carrying the plasmid. Grow bacteria containing plasmid expressing Taq DNA ... http://elegans.uky.edu/blog/?p=171 Last October, NASA's LCROSS mission slammed a spent rocket booster then the LCROSS spacecraft itself into the moon. No debris plume was seen from Earth, but observations from LCROSS of the booster hitting indicate the presence of water on the moon. How much water? Most news accounts ... http://elegans.uky.edu/blog/?p=170 Interesting letter about the evolution of the glucocorticoid receptor from Joe Thornton, a biologist at the University of Oregon. Thornton's lab has figured out some of the details on how this receptor evolved. Thornton's writing this because creationist Behe is passing off a mangled version of his work ... http://elegans.uky.edu/blog/?p=168 Stepper motors are easier to control than servos, but they typically produce lower power. A number of people have built stepper motor run CNC projects, so for small or mid-size CNC control they work. I have three bipolar stepper motors, but seven 6-wire unipolar steppers plus other unipolar steppers with ... http://elegans.uky.edu/blog/?p=167 So I have a box of motors scavenged from old electronic equipment. The first step was figuring out what I have. I have four identical Pittman servo motors with attached optical encoders. They have two leads for motor control and four leads for the encoders, Vc, Gnd, quadrature ... http://elegans.uky.edu/blog/?p=166