Current limiting with an visual indicator of overload

  Hello,

I'm currently planning the conversion of an AT computer power supply
that I have lying around into a base supply for my hobbyist electronics
projects .
I know that there is a reason a lab supply costs that much, but for the
use I'm planning, a computer supply will be enough.
However, I would like to protect it against overload as I have no idea
if the supply in itself is fitted with such circuit.
I know I can use a fuse, or a PPTC but this type of circuit does not
give me any indication that it is about to shutdown the power.
I have in mind an old model train transformer that had a red light that
progressively lights up as one approaches overload up until it is fully
on and the supply to the system is shutdown
I would thus like to reproduce this kind of behavior but I must admit
that I'm a bit lost as to what starting point I could use.
What resources would you recommend?
Are there any base circuits that I can modify easily to add an indicator
light?

Thanks for your help
OBones

 OBones wrote:


As far as I am aware AT PSU don't have any SC protection but ATX PSU
do !

--
Best Regards:
                     Baron.

 
"OBones"

** The supply has a lamp ( ie a 12 volt, 21 watt car brake lamp ) in series
with the output.



**  Why not start with a lamp or two ?

  6 volt for the 5 volt rail and 12 volt  for them.


.....   Phil

 Phil Allison wrote:


Wouldn't the voltage drop modify the output voltage even for low currents?
I mean, the point is indeed to lower the voltage when there is a lot of
current going through, even to the point that there is not enough
voltage anymore for the circuit, but what about normal operating conditions?

 Try this:
http://datasheets.maxim-ic.com/en/ds/MAX4172.pdf

This even gives you an output current. You may have to amplify it depending
on the light indicator you choose.

Regards

--
Bill Naylor
www.electronworks.co.uk
Electronic Kits for Education and Fun