I have a IRF830 power mosfet chip that I purchased a NTE2378 chip to replace (my thinking here is more power handling - heavier duty). Now I do notice when I go to NTE's cross-reference webpage they list a NTE2398(which is spot-on spec. wise). I guess I am showing my lack of understanding about all the parameters on the datasheets but I really did think I could pop-it in and the circuit would work, it doesn't. Now of course I will return to the right part to get the circuit working again, I just wondered if some responses could be posted that might assist others thinking of doing the same to avoid costly parts or wasted time.

Thanks in advance

DC

 

Generally you should try to substitute a transistor with near equivalent characteristics, unless you understand all the transistor parameters and know which may be critical in your application.

Important parameters for using them as a switch are:
Maximum drain voltage Vds
Maximum drain current Ids
Vgs-on for minimum ON resistance (not Vgs threshold voltage)
Maximum ON resistance at Vgson
Gate charge (to turn on and off)
Power rating
Switching time (often limited by the gate driver circuit)