Dying battery sim

[scotsman]

I remember seeing a "dying battery simulator" that was "made from" a capacitor and a 250k pot..  If my memory is correct.  I've seached the forum and can't find it.. Anyone else run across this?


Grazie!

[R.G.]

IMHO, that's a very poor way to do a dying battery sim.

Read http://www.geofex.com/Article_Folders/pedalbdpwr/pedalbd.htm for a good way to do it. This article predated the patent application for the same technique (which was later granted) by about 6 months, so GEO may well be a good source for people to look up new things to patent.

[petemoore]

  I just used an LM317 Voltage regulator, works great, drops voltage [what was that...no more than a volt or so IIRC] when in use, then you can adjust voltage down to...where it starts getting super hot....which again IIRC is about <3v .
 

[hank reynolds 3rd]

http://www.muzique.com/lab/patent2.htm

try here...there;s a couple to go off...
Sam

[Mark Hammer]

Older battery vs dying battery.  Two different things.  An older battery may be able to deliver a sturdy 8v no matter how you wallop the strings. Lower voltage but enough current.  Changes the behaviour of the circuit but not  in the same way.  Dying batteries are different, and this is a constant scab I pick at whenever this topic comes up.

If you stick a bunch of stuff between a wallwart and a stompbox, you may alter the supply voltage and current, but what you get after those alterations is constant.  The 300ma wallwart remains capable of delivering 300ma if asked for.  In real life, batteries will semi-recharge, if given time.  Take your average well-used 9v battery and leave it alone for an hour or two, and you'll find it has more juice when you go to use it.  Of course that recuperated juice won't last long under use, and very soon the battery finds itself like an out of shape army recruit (or like me) struggling and trying desparately to do that one more pushup, and not being able to do more than the beginnings of one before the arms give out.

These are dynamic, rather than static, changes that depend on the current-delivery-capacity of the battery, and how much current the pedal needs at that moment.  In a sense, what would truly simulate a dying battery with a wallwart or other steady supply would be something that changes current delivery capacity depending on "most recent demands".  Not an enveope follower sort of thing, but something that averaged out total current draw (number of notes times picking strength times gain setting), and used that information to change the current delivery capability of the supply.  Friom what I can see, none of that is incorporated into the drawings shown at Jack's site.

[dano12]

Or you could go with the simple/easy/works approach:

http://beavisaudio.com/Projects/DBS/

[scotsman]

Thats it!  Thanks!!

[Paul Perry (Frostwave)]

http://beavisaudio.com/Projects/DBS/

I notice the writer there says that "if a simple series pot is good enough for Zvex, it's good enough for me".
Fair enough.... but, doing one with independent voltage & resistance control DOES give a wider sonic pallet.
Whether it is worthwhile, depends on what fx you are using it with, and the desires of the user.

[amz-fx]

Not an enveope follower sort of thing, but something that averaged out total current draw (number of notes times picking strength times gain setting), and used that information to change the current delivery capability of the supply.  Friom what I can see, none of that is incorporated into the drawings shown at Jack's site.

The version that I designd with a diode on the output has a bit of dynamic impedance since the voltage drop of the diode varies slightly with the current draw...  it's small but definitely there.

regards, Jack

[Mark Hammer]

Then I plead electronic ignorance.   I am also heartened.

Is it possible to build on that "small but there" change, or does that turn the circuit into something far more complex?