http://www.pfranc.com/projects/turbine/duh.htm
http://www.ikalogic.com/d_tach.php
http://www.freemansgarage.com/tach.html
http://www.stefanv.com/electronics/tachometer.html
http://blog.makezine.com/archive/2007/09/arduinobased_optical_tach.html
http://www.instructables.com/id/Arduino-Based-Optical-Tachometer/
http://www.nicolas.benezan.de/Gasturbines/Turbocharger.html
http://www.nicolas.benezan.de/Gasturbines/SensorPickup.html
http://www.technologie-entwicklung.de/Gasturbines/gasturbines.html
http://www.technologie-entwicklung.de/Gasturbines/Balancing_Tool/balancing_tool.html
http://www.technologie-entwicklung.de/Gasturbines/Balancing_Tool/Available_Parts/available_parts.html
http://www.monstaka.com/F_frame.html?http://www.monstaka.com/