Dead battery simulator

[John Lyons]

A couple years ago I read an article on the net about a dead battery simulator that had controls for voltage and impedence. The artilcle went into all the theory about almost dead battery's and why voltage and impedence played roles in the sound with guitar effects.

Anybody know about this or have the article? I can't seem to find it now.

Thanks.

John

[Samuel]

Think that one's on GEOFex no?

[vseriesamps]

I have the unit that was marketed for this it was called the BattMan. There are four power terminals, two normal and two that go from like 4.5v to 9.5v. I wish I was a little further along with the electronics thing I would try to make a schematic.

It's a neat unit but I have to say I don't use the "sag" settings very much if at all. They mostly only work on very vintage circuits and even when they do, I often prefer the normal settings - like with my TubeScreamer.

That said, definitely continue your research. There may be something for you there. You might could just find one on eBay if nothing else.

Good luck!
K

[John Lyons]

Hmmm. I don't seem to be able to find it at GEO. Maybe I'm searching with the wrong name...?

Does the Battman have control over voltage as well as impedance? In the article I'm I remember, it made a point about when voltage dropped the impedance changed as well, and this had something to do with the sound that  followed.

[amz-fx]

Maybe it was this one?

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

regards, Jack

[seanm]

Maybe it was this one?

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

regards, Jack

Hey Jack, did you file the patent? Your year is up  

[vseriesamps]

The only controls were for voltage. If that changed impedance as well, it was just a side effect I guess.

Can't you just control impedance with your volume knob?

K

[snap]

your volume knob changes the apparent impedance of the signal source,
while the sag circuit varies the internal resistance of the powersupply.

[ESPguitar]

geofex.com--> FX projects (on the menu line) --->and on that page you'll find MISCELLANEOUS and under that you'll find pedal board power supply..

It has a dying battery function..

Robin

[R.G.]

It turns out that someone filed for and received a patent for the idea of using a variable voltage source with a resistor in series with the output of it to emulate a dying 9V battery in effects.

The application for the patent was turned in to the patent office six months *after* the article on the dying battery emulator first appeared on my web site.

The idea was not new with me. Basic circuits classes in EE teach Thevenin equivalent circuits to get across the idea that *any* voltage source can be modelled essentially perfectly by an ideal voltage source (i.e. one that can supply its output voltage with an infinite amount of current if needed) and an impedance in series with it to model the sag that real voltage sources always have.

The patent is clearly (to me, at least) invalid because (a) it claims the discovery or reduction to practice of something that has been in practice and common knowledge to EEs for a significant fraction of a century and (b) the only possible novelty is the use of the technique to power musical effects as claimed; even if this were a substantial claim (IMHO it's not)  my publication of the idea predated the application.

It is possible that this patent application was written up based on seeing my web page. I don't have any evidence for or against that, it's just possible. It's possible that the inventor was really ignorant of the base of EE knowledge that makes the patent a simple application of widely known practice to anyone "skilled in the art" as the patent guys say. It's possible that the guy slaved long and hard in a garret, never once looking at the internet, never reading or having heard anything about GEO, polishing, testing, and reworking the germ of an idea and finally after years of effort, many failed attempts and the scorn of his fellows produced a masterpiece.

It's possible.

[ESPguitar]

It turns out that someone filed for and received a patent for the idea of using a variable voltage source with a resistor in series with the output of it to emulate a dying 9V battery in effects.

The application for the patent was turned in to the patent office six months *after* the article on the dying battery emulator first appeared on my web site.

The idea was not new with me. Basic circuits classes in EE teach Thevenin equivalent circuits to get across the idea that *any* voltage source can be modelled essentially perfectly by an ideal voltage source (i.e. one that can supply its output voltage with an infinite amount of current if needed) and an impedance in series with it to model the sag that real voltage sources always have.

The patent is clearly (to me, at least) invalid because (a) it claims the discovery or reduction to practice of something that has been in practice and common knowledge to EEs for a significant fraction of a century and (b) the only possible novelty is the use of the technique to power musical effects as claimed; even if this were a substantial claim (IMHO it's not)  my publication of the idea predated the application.

It is possible that this patent application was written up based on seeing my web page. I don't have any evidence for or against that, it's just possible. It's possible that the inventor was really ignorant of the base of EE knowledge that makes the patent a simple application of widely known practice to anyone "skilled in the art" as the patent guys say. It's possible that the guy slaved long and hard in a garret, never once looking at the internet, never reading or having heard anything about GEO, polishing, testing, and reworking the germ of an idea and finally after years of effort, many failed attempts and the scorn of his fellows produced a masterpiece.

It's possible.

Hmm..

Doesn't voodoo lab use that on two of the outputs on the Pedal Power2??

How can you take a patent on something like that.. Just wonderin' what people think..

RB

[R.G.]

Doesn't voodoo lab use that on two of the outputs on the Pedal Power2??

There's at least one commercial supply that does. Could be them.

How can you take a patent on something like that..

You just blast in your patent application and a not-particularly-observant patent examiner says "Kewl, looks good to me" or something similar, not knowing the state of the art of his or her specialty.

Just wonderin' what people think..

Unfortunately, what people think is completely irrelevant. In this case, the patent examiner and eventually the courts are the only thing that count.

[ESPguitar]

Anyway, i think thats voodoo lab..

And it's genius..
:wink:

RB

[Mark Hammer]

Do not mistake the reduced voltage available with some circuits for what actually happens with a dying battery, and especially for inter-category differences in how batteries die.

As carbon-zinc batteries die, they seem to be able to produce a brief delivery of current at note attack, due to their generally larger surface contact area between cells.  Of course, due to the decline in "a buncha stuff" within the cells, that brief surge of available current is not available for more than an instant, and the battery just gives up until it can catch its breath.  At least that's my reading of it.

All alkaline batteries that I've every seen (and I pull a lot of them apart to make battery connectors; see the article at hammer.ampage.org if you haven't already) use sub-AAA cells that have much smaller contact areas between them.  How current is delivered in response to transients, and how the battery recovers from this, is different in alkalines.

The long and the short of it is that what we call "dying battery" is a lot more complex than simply sticking a diode in series with the battery to drop the supply voltage, or some other sort of more complex regulation.  Dying battery effects/tone depend on a very dynamic interaction between the gain setting of the pedal (and consequent current needs), the input signal, and the internal state/traits of the battery itself.  I suppose one COULD simulate that with some intelligent DSP that reads input signal level, but it would probably be a lot more complex than what is currently out there.  I suppose I can always be persuaded otherwise, but my starting position is that dying battery phenomena are too dynamic and interactve to be mimicked by circuits that provide a fixed, stable change to power supply.

P.S.:  People should take a look at the Charles R. Fischer circuit that was published posthumously in Electronic Musician.  It is posted over at GGG.  Fischer used an LM334Z current regulator to adjust current supplied to the 4049 invertor section used in the circuit.  To my mind, we have not discussed this innovation nearly enough.

[ocelot]

http://www.lynx.bc.ca/~jc/pedalsDynacomp.html

This is how he is doing it

[zachary vex]

i put  a sag control on the fuzz factory in 1995 (stability pot.)  it's not patentable... it's just series resistance, like a battery develops.  

if anyone can demonstrate that anything other than series resistance develops in a dying battery, i'd love to see the science.  8^)

[R.G.]

i put a sag control on the fuzz factory in 1995 (stability pot.)

The sag control does more for oscillatory feedback than it does for power supply sag.

if anyone can demonstrate that anything other than series resistance develops in a dying battery, i'd love to see the science.

Look up distributed versus lumped parameters.

[WGTP]

Very interesting stuff.  It once again reminds me of how much of this stuff I DON'T know.

IMHO the battery strength and perhaps type (after reading Mr. Hammer's explaination) effect a distortion (based on op amps) more that the op amp used i.e. 4558, TL072, etc.  If you think that is silly, try subing a fresh 10v for a vintage 8v.  At least on my breadboard dual op amp distortion, it is very noticeable.  I have to change tone caps when I switch to the new unit and it still isn't the same dynamics wise.   :roll:

[Mark Hammer]

When I was a much younger lad, I was stricken with mononucleosis and stuck at home.  What saved my sould was my transistor radio.  I couldn't get out of the house to get new batteries, so I memorized the playlist (it was all AM is those days), and would conserve my batteries until the time when I thought/knew my favourite songs would come on (usually the opening guitar riff from the Hollies' "Look Through Any Window" - still kicks ass).  At the appointed time, I'd turn on the radio at a very modest volume and the batteries would take me to the end of the song at which point they'd give out.  I'd wait a few more hours and do it again.

Here's the thing.  When not in use, the batteries regain some current as a function of whatever it is goes on inside them, and "spend" that current, as a function of, yes, the internal resistance in the cells and the resistance of the inter-cell contacts, but also a function of the current draw in the powered device.  If the current draw does not exceed the battery's ability to "recoup its losses", then the battery can go for a while, even when dying.  When high gain devices (like fuzzes) causes sudden instantaneous current draws, the non-fresh battery is placed in a take-3-steps-forward-and-5-steps-back situation with respect to supplying current - i.e., it can't recover asfast as it is being asked to spend current.  Obviously the relationship between how much current-providing capacity is lost while delivering current to a circuit, and the battery's ability to respond to transients at high gain, will be a function of battery type, battery age, etc.

All of this is to say that series resistance, like the Stab control mimic *some* of the aspects of a battery receiving a pension cheque, but not all of them.  That in itself is not "wrong", merely an interesting performance feature/control.  However, I think those whose dream involves mimicking a Fuzz Face with a red Eveready Classic about to pack it in, will need something more complex.  It is the instability of a battery one is trying to mimic.  I do not expect a fresh battery with a current limiting resistor to behave like one that runs out of breath easily.

And that's what I learned when I was sick in 1966 or 1967.