Electronics Infoline Web

Low battery voltage flasher

http://www.discovercircuits.com/PDF-FILES/undervol.pdf

Low cost 23 cm linear transverter

http://www.mrs.bt.co.uk/dubus/8501-1.pdf

http://www.mrs.bt.co.uk/dubus/8701-4.pdf

http://www.imagineeringezine.com/PDF-FILES/3vledfs1.pdf

http://www.discovercircuits.com/PDF-FILES/3vledfs1.pdf

This is a collection of inverting and non-inverting active low pass filter circuits.

http://www.discovercircuits.com/PDF-FILES/lowpass.pdf

http://ourworld.compuserve.com/homepages/Bill_Bowden/page4.htm#triple.gif

operated from 12V battery and shows it's voltage

http://www.solorb.com/gfc/elect/solarcirc/vom/index.html

http://www.twysted-pair.com/74lsxx.htm

uses four-wire measurement technique

http://www.angelfire.com/electronic/funwithtubes/low_res_meter.html