transistor question

straight swap isn't working in most cases

some gymnastic needed, read - some more complications and complexity, and some luck - to get same results

best scenario is - having not just knowledge how to, but also projected performance, not necessary identical to original circuit

anyhow, contemplation as this one is best when applied to exact circuit, not in general
 
As Zen Mod said, the circuit has to change. For a regulator pass, Mosfets need additional parts to protect the gate. Bipolars need more current drive. Those two are pretty different.

It's best you not try. It might work if you are lucky, but it won't work as well as it could. Most often it will not work.
 
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