> > > The guaranteed switching time for the 1N4148 is 4 nS. The switching time > for a unidirectional TVS > is less than 1 pS; I calculate that to be 4000 times faster. But if your transistor can be made to switch off in a time of about a microsecond, neither of these will matter. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist