homebrew eeg

i came across this project today. looks pretty cool, especially when combined with brainwave synchronization with binaural beats. i would need to make some electrodes, but they have designs for both passive (saltwater) electrodes and fairly simple active ones. i could probably get silver wire from a jewelry supplier. EDIT: i think active electrodes are the way to go. the links here to joe's, jim's, and pedro's (the other 2 links to bioera.net are dead) show schematics and construction tips. jim and pedro use joerg's modification of jarek's original v2 prototype. looks like joerg made the following changes. 1. added a 200 ohm decoupling resistor between the opamp and the shield 2. changed the power bypass cap from 100nF to 10nF 3. added what looks like a lowpass with 2 100pF caps and a 10k ohm resistor 4. added 100 ohm power protection resistor to power supply 5. added a 2v 'vgnd' for bias current electrode

led circuits

i've seen a number of circuits online lately for squeezing the last joule from dead batteries and using it to power an led. this page seems to have the most info.

homebrew scopes

i found instructions for building a scope from a dspic and a few other components. looks easy enough for a dilettante like me. the author says the next version might allow for upload to a computer. i would be all over that. here's another one that might hold promise. also has some info on usb interfacing for homebrew electronics. here's one that is more capable but _way_ more complicated.

compressing text images

i was playing around with potrace and found it to be ideal for compressing images of text. (i tried autotrace, too, but i couldn't get it working well within 2 minutes and gave up.) based on settings from the example page, here are some good defaults to try: mkbitmap -s 2 -t 0.48 test.eps if the image is blurry or has too many colors, you might want to add '-f 2' to the mkbitmap options to make it do a high-pass filter. only problem with that is, it will mess up graphics. the above options worked really well for an image that was about 2000 pixels across a page of text. the eps file was only about 1/10 the size of the pbm, which was only about 1/5 the size of the original ppm. and it still looks great -- very readable. apparently inkscape uses potrace and allows color instead of just b&w. maybe i can figure out how to pipe through that...

teddy roosevelt

"It is not the critic who counts, not the man who points out how the strong man stumbles or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood, who strives valiantly, who errs and comes up short again and again. Because there is no effort without error and shortcomings, he who knows the great devotion, who spends himself in a worthy cause, who at the best knows in the end the high achievement of triumph and who at worst, if he fails while daring greatly, knows his place shall never be with those timid and cold souls who know neither victory nor defeat" -theodore roosevelt i find this quote very inspiring. here's one i'm working on: "the greatest failure is fear to try." -duhctaep

knowledge representation

i've been thinking about planning and organization lately, especially with respect to innovation and creativity. i was reminded of this when i saw gentoo update freemind, a mind mapping program. five minutes of poking around on wikipedia turned up articles on concept mapping, semantic networks, and other things that look similar to the directed graphs i've started to use. i've been trying to find a way to represent dependencies and alternatives so that i can identify critical paths and distractions. maybe i should look into concept mapping and semantic networks for this. the knowledge representation category has a number of related articles.