Online Calculators...

Unit Conversion
http://www.krstarica.com/eng/conversion/index.php?vrednost=100&tip=10&iz=17&u=15[FONT=verdana,arial,helvetica]Convert Voltage Gain to Decibels
http://www.muzique.com/schem/decibel.htm[/FONT]
Resistor Color Codes
http://samengstrom.com/nxl/3660/4_band_resistor_color_code_page.en.html
[FONT=verdana,arial,helvetica]Calculate Resistor Value for LED
http://www.muzique.com/schem/led.htm
[/FONT][FONT=verdana,arial,helvetica]Calculate LM317 Resistor Values[/FONT]
[FONT=verdana,arial,helvetica]http://www.muzique.com/schem/lm317.htm
[/FONT][FONT=Arial,helvetica]Op-Amp Noise Calculator
[/FONT][FONT=Arial,helvetica]http://www.muzique.com/schem/opcalc.htm
[/FONT][FONT=arial,helvetica][SIZE=-1]Various speaker design calculators
[/SIZE][/FONT][FONT=Arial,helvetica]http://www.mhsoft.nl/spk_calc.asp[/FONT]
Inductance
[FONT=Arial,helvetica]http://www.consultrsr.com/resources/eis/induct5.htm[/FONT]
Resistance of Wire
http://www.cirris.com/testing/resistance/wire.html
Cartridge Loading
http://www.hagtech.com/loading.html


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Loudspeaker-Cable Applet

http://www.st-andrews.ac.uk/~jcgl/Scots_Guide/audio/Java/twin.html

Analogue Electronics with a special emphasis on Audio-related topics

http://www.st-andrews.ac.uk/~jcgl/Scots_Guide/audio/Analog.html

Op-Amp...
http://tangentsoft.net/audio/calc.html