Anyone using a weak battery simulated power supply?

[guilds100]

Im getting ready to build a multi effects unit. I planned on using the spyder power supply to power it. While reading up on the power supply, i noticed a circuit for 9v, and a circuit with adjustable voltage to simulate a worn out battery. My multi effects unitl will be using a comp, sho boost, 3 distortions, rebote delay, maybe small stone or small clone. Which of these circuits would benefit from the worn battery simulation?

[frequencycentral]

Ask Dano: http://www.beavisaudio.com/Projects/DBS/

[MikeH]

It's really easy to determine that.  I'm pretty sure you just use a pot to increase the resistance going into the effect.  Once you have the circuits build just hook up a pot between your power supply and V+ and decrease the voltage and see if there's any effect.

My guess:

SHO- no
3 distortions- maybe
rebote- probably not
small clone, small stone- no

Usually it's transistor based fuzz effects that benefit most

[frequencycentral]

small clone, small stone- no

You might be surprised with the Small Stone - Jean Michel Jarre had his modded to simulate a dying battery - part of his trademade string synth sound.

[fpaul]

I've read that voltage affects the dynacomp.  It did seem to affect mine(before I lost it), if I remember correctly, but I never did any measurements.  Haven't finished my replacement yet.

[MikeH]

small clone, small stone- no

You might be surprised with the Small Stone - Jean Michel Jarre had his modded to simulate a dying battery - part of his trademade string synth sound.

Well, it was a 'guess'.   Interesting though, I always thought BBE chips just plain quit when they didn't see enough voltage, I'll have to try it with mine.

[aron]

What about that great demo of the Bosstone!?

[frequencycentral]

small clone, small stone- no

You might be surprised with the Small Stone - Jean Michel Jarre had his modded to simulate a dying battery - part of his trademade string synth sound.

Well, it was a 'guess'.   Interesting though, I always thought BBE chips just plain quit when they didn't see enough voltage, I'll have to try it with mine.

That's the Stone (CA3094's) not the Clone.

[Boogdish]

I just built a big muff with a built in low battery simulator.  I did it because when I was tweaking the circuit on my breadboard, I was (unwittingly) using a half dead battery and when I heard the pedal on full power thought it sounded horrid.  I've never tried running any of my other pedals through an external low battery simulator though.

[newfish]

If you have a box that has no extrernal power socket, could you effectively build a 'sag' control into your pedals?

I'm thinking it would be some sort of voltage divider - or would you have to drop the current too?

[Eb7+9]

when batteries die it's because their internal resistance rises - that's why batteries need to be tested under reasonable load and not just open ... all you need is a 20k trimmer in series with the hot wire on your voltage source - adjust to taste depending on circuit current draw ... may as well overstate this here, any circuit that isn't exclusively built around op-amp and discrete "follower" stages has a likely chance of reacting to a resistively sagged supply voltage ...

[earthtonesaudio]

I personally like the sound of a 'starved' tube screamer.  But keep in mind there are several things you can do which have different effects:

1. Add series resistance to the V+ line.  This limits current to the effect and drops voltage at the same time, AND creates asymmetry in the maximum possible output voltage swing.  Adding a little even-order distortion might make a lot of different effects sound better to your ears, not just distortions.
2. Use an adjustable voltage regulator.  Not quite as interesting, in my opinion, because you don't get the asymmetry factor, but some effects benefit a lot from this (CMOS distortions I've found in particular like this), and all effects benefit from the regulation in terms of reduced noise.
3. Voltage divider: haven't tried this, but I think it would behave a lot like the series resistor.
4. The less current an effect draws, the more series resistance you'll need to add in order to drop the voltage.  However, you can probably hear a difference with any series resistance over 1k or so.  I like a 10k 'starve' control, it seems to work for most effects.

[guilds100]

Thanks for the replies. I think I'll add the geo dying battery power supply to each channel of the spyder power supply if not for the effect that is there now, but for possible future use. 

[Solidhex]

I personally like the sound of a 'starved' tube screamer.  But keep in mind there are several things you can do which have different effects:

1. Add series resistance to the V+ line.  This limits current to the effect and drops voltage at the same time, AND creates asymmetry in the maximum possible output voltage swing.  Adding a little even-order distortion might make a lot of different effects sound better to your ears, not just distortions.
2. Use an adjustable voltage regulator.  Not quite as interesting, in my opinion, because you don't get the asymmetry factor, but some effects benefit a lot from this (CMOS distortions I've found in particular like this), and all effects benefit from the regulation in terms of reduced noise.
3. Voltage divider: haven't tried this, but I think it would behave a lot like the series resistor.
4. The less current an effect draws, the more series resistance you'll need to add in order to drop the voltage.  However, you can probably hear a difference with any series resistance over 1k or so.  I like a 10k 'starve' control, it seems to work for most effects.

Yo

  What's the range of voltage you could "starve" from a 9 volt battery supply? Could you get a 9 volt supply down to 3 volts just with a resistor or voltage divider or would you just end up frying stuff?

--Brad

[petemoore]

  LM317 adjustable Voltage regulator.
  when first putting current through it, or increasing current, check it often so you don't scald your finger.
  Depending on the V drop [and correct wiring] you might need a heat sink.
  Then you can DMM and adjust input levels etc. to see how the circuits respond @ different voltages / settings.
  AMZ has a Low voltage article.