[Harp-L] RE: Kinder AFB batteries

["Paul" <lesspaul@xxxxxxxxx>]

John wrote: The thing to consider about "converting" a Kinder AFB+ to be
used with wall warts/adapters is the amp draw of the AFB+. 9-volt adapters
can put out 9-volts at a very low amp rating. They can also put out quite a
bit of juice at a higher rating (usually stated in milliamps). This is why
you can't (shouldn't) hook up the adapter from your brand X delay pedal to
your brand Y reverb pedal; even if the polarity and jack size is the same." 

I think the danger implied in your post is highly overstated. 

If the adapter type is correct (AC or DC) and the voltage is correct, the
chance of damage is virtually nil.  There is a common misconception that a
high-current adapter will "blow out" a small device. This is not so. A
device will only draw as much current as it needs.

While there is an outside chance of an underrated adapter causing damage if
left connected for an extended period of time, the lack of proper operation
would give plenty of advance warning that the current is insufficient.  You
might want to consider the fact that a dying battery also does not provide
sufficient current. 

(I am aware that a dying battery will provide as much current as the device
can draw, and that the voltage will sag in an effort to maintain that
current, but the facts remain that the danger is overstated.)

Furthermore, it is stated that "good batteries (e.g. - Energizer Industrial)
last for 165 hours)". 
A typical 9volt battery is rarely capable of more than 450mah
(milli-ampere-hours). This implies a current drain of roughly 3 milli-amps
per hour to remain on for 165 hours. I don't know of any DC adapter which
would not produce more than enough current to drive 3ma. 

I realize your post was well-intended, but the fact is, a 9-volt adapter,
properly polarized, is a very good solution to powering the device. I base
this statement on 30 years of electronics education, development, design,
and building experience. 




No virus found in this outgoing message.
Checked by AVG. 
Version: 7.5.524 / Virus Database: 270.5.4/1566 - Release Date: 7/22/2008
6:00 AM