Re: OT Variable Power Supplies for Stomp Box Pedals

[andy butler <akbutler@tiscali.co.uk>]

Rick Walker wrote:


> Anyway,  I told him that I keep a bunch of old used 9 volt batteries (in 
> various
> short lengths of time before their battery death) and that , sometimes,  
> when I
> am tracking something into my computer,  I'll switch out 4 or 5 of them 
> on the
> offchance that the particular stomp box pedal that I'm working with will
> freakout as the voltage drops precipitously.
> 
> He then hipped me to the fact that there are companies that make 
> variable power supplies
> (specialty hospital equipment, apparently, have the need these things 
> for various equipment).
> 


Variable power supplies are commonly used by people who work with 
electronics,
and are sold under the name "Bench power supplies". Some of them can
provide a continuously variable voltage.
That won't mimic a dying battery tho' (may still produce interesting 
behaviour
changes in your gear, but unlikely the same ones).

The difference between a good battery 
and a flat one is not actually Voltage, it's something called 
internal resistance. 

So...in theory...all you need to do to make a good battery resemble
a dying one is add a resistance in series.

I'm guess we're into "get someone to solder it for me" territory here
(unless you bought that fleamarket bargain soldering iron)

The resistor you need ...well I don't know what would work best...
...you could try starting with a 1k log pot then turn the spindle
till the desired artefacts appeared.

andy