May I ask a "stupid" question?
Though it has been a long time since I have done that kind of electronics, looking at the first post and the "fuse".
I got confused where the main path is until I realised the main path is via the transistor - right?
The circuit doesn't look right.
Why?
Ok, here's what I see:
At start up, the SCR isn't conducting and the base of the transistor is "LOW". So it is off.
The button is pressed and the base is taken HIGH and so the transistor turns on.
However, there is no base current limiting, and transistors are currrent driven.
Though you want it to be ON and not just "on" FULL + voltage on the base?
Then I am wondering how it turns off when a short circuit happens on the output.
After R1 is the "load" and so if a short happens, the emitter of the transistor and R1 would be at 0v, rather than onto the load.
There is nothing there to bias the transistor OFF and stop the SCR conducting - that I can resolve.
Sorry, but what am I missing?
I shall run off and ask "Mr Google" but want to mention it here for the sake of getting pgmartin to check that part of it.