Plz Help - Electronic Fuse for a customized application

[j37prakash]

Dear Friends, I need a simple electronic fuse circuit that can be used exactly as we use a fuse. In the circuits normally posted in all forums as in the attached gif file, we have to push the switch every time we switch the power on.
I need a circuit which energises by itself as we switch on the power and must fail only if the current drawn extends the set limit. Please give me feedback ASAP as this project is very urgent for me
Thank you in advance

 

[Boncuk]

Short out the switch and use a "one-way" SCR rated for the max allowable current flow (Itotal - IT1)

It will burn up at over current and not supply base voltage and current to the transistor.

I doubt this method is cheaper than using a fuse.

Boncuk

 

[crutschow]

You could perhaps use a one-shot, such as a 555, to capacitively couple a turn-on pulse to the SCR gate when the power come on.

Note: Be sure and add a diode in series with the gate to block any reverse voltage on the gate when the SCR turns on.

 

[j37prakash]

Thanks guys for the useful replies.