[sdiy] BIG PSU ISSUES

[Dave Manley]

Dan Snazelle wrote:
> what fuses do you guys recommend (something that smokes easy...i like the 22 ohms because i smell it as SOON as something has gone wrong. the fuses on my psu have never once tripped but i have burnt lots of resistors...thank god
>
> --------------------------------------------
For design/debugging you should buy a bench supply with adjustable 
voltage *and* adjustable current limiting.  This allows you to set a max 
current the supply will deliver, then you don't have to worry about a 
bulk supply turning a wiring error into a puff of smoke.  Before 
powering up a new circuit it is a good idea to use your ohm meter to 
measure between the power rails and ground and make sure you don't have 
an unexpectedly low resistance or a dead short.  With the adjustable 
bench supply you can set the voltage (unloaded), then slowly bring up 
the current while watching the ammeter on the supply and stop if you see 
the circuit drawing way too much current.

Large bulk supplies are good for a finished design, but not the best for 
debugging.

-Dave