http://www.web-ee.com/Schematics/Inclinometer/Inclinometer.htm
you can boost the available current output of 78xx series of voltage regulators with this circuit
http://www.mitedu.freeserve.co.uk/Circuits/Power/boosti.htm
A huge list of references about inductance and coils.
http://members.aol.com/marctt/Technical/Inductance_References.htm
http://www.ee.surrey.ac.uk/Workshop/advice/coils/index.html
http://www.web-ee.com/Schematics/Inductance Meter/Inductance Meter.htm
It is excellent for tracing wiring behind walls, receiving audio from an induction transmitter, hearing lightning and other electric discharges, and monitoring a telephone or other device that produces an audio magnetic field
http://www.techlib.com/electronics/induction.html
All inductive devices, operating in d.c. circuitry, which are switched on and off should have a diode connected across their coils to catch the inductive fly back. This page explains why.
http://www.4qdtec.com/catch.html
simple device for detecting audio-frequency electromagnetic signals, such as those emanating from a loudspeaker, or it's cable
http://free.prohosting.com/~pointsrc/audio/induct.html
Using an oscilloscope and a signal generator this will measure resonant frequencies from KHz to over 10MHz, adds only few picofarads of parallel capacitance to inductor
http://www.imagineeringezine.com/PDF-FILES/coiltest.pdf
Inductors: What are they good for?
http://www.williamson-labs.com/480_rlc-l.htm