[sdiy] Current Limiting [was: Bypass caps]

[Seb Francis]

Paul Perry wrote:

>If the frequency of he sawtooth blips is equal to the mains frequency, 
>then you are seeing the input voltage to the regulator falling below 
>the minimum headroom it needs. This can make a patch sound nice and 
>growly..... but you don't want it ALL the time!
>
>  
>
I didn't notice what frequency it was, but it was definitely the current 
limiting kicking in (as opposed to the smoothing caps letting through 
ripple) because when I changed the current-sense resistor value it went 
away.


James Patchell wrote:

> Power One Supply don't current limit...they fold back.  This is 
> because those things are generally pretty beefy....A power supply with 
> a standard current limit will eventually charge capacitors up.  On the 
> LM723, it seems like I remember you can set it up to either current 
> limit or fold back....I just checked the data sheet...and yes, you can 
> make either a fold back or standard current limit regulator with it.
>
> The LM78xx regulators only have current limit.
>
>
So it would seem that a current limiting design is rather better than a 
fold back design if you are intending to run your power supply close to 
its current limit.

I guess current fold back offers better protection against short circuit 
fire hazards though ;)

Seb