can detect the peak of either positive or negative inputs
http://www.edn.com/archives/1994/051294/10di3.htm
With portable applications on the rise, designers are turning to dynamic power-conservation techniques to delay the inevitable dead battery.
http://www.edn.com/article/CA189467.html
simple RC servo motor tester or controller based on CD4001. A potentiometer controls the servo position
http://www.tuug.fi/~isaarine/electronics/servo-test/
http://ourworld.compuserve.com/homepages/Bill_Bowden/page10.htm#5volts.gif
http://www.epanorama.net/documents/lights/laser_psu.html
uses pair of 3N3055 transistors to give out currents up to 15A
http://ourworld.compuserve.com/homepages/Bill_Bowden/page12.htm
http://www.e-insite.net/ednmag/archives/1994/060994/12df4.htm
workings of lead-acid battery.
http://www.batterycouncil.org/works.html
http://www.wvic.com/how-gen-works.htm
from the basic concept at work to the actual chemistry going on inside a battery to what the future holds for batteries and possible power sources that could replace them!
http://www.howstuffworks.com/battery.htm