Measure the voltages at the collector and emitter. If the collector is at Vcc (cutoff) or 0V (saturation) when it should be mid-supply, your substitute has the wrong gain or leakage.
Do you have a favorite equivalent book edition? Share your most bizarre transistor substitution success story in the comments below. all transistor equivalent book
A transistor equivalent book is a specialized reference tool used by engineers and hobbyists to identify suitable replacement components for obsolete or hard-to-find transistors. These guides prioritize matching critical electrical and physical characteristics rather than just part numbers. Measure the voltages at the collector and emitter
If you plug a 2N3904 into a socket designed for a BC548 without crossing leads , you will destroy the transistor instantly. A good equivalent book provides pinout diagrams or footnotes. all transistor equivalent book