I am trying to get this circuit to work but get no flash from the back emf. My coil is a 12mH unit not 10.5mH. Would this make a difference? Does any aspect of this circuit look incomplete or inaccurate?
http://www.fas.harvard.edu/~scdiroff/lds/ElectricityMagnetism/BackEMF/BackEMF.html
http://www.fas.harvard.edu/~scdiroff/lds/ElectricityMagnetism/BackEMF/BackEMF.html