9 volt regulator from a battery

[bent]

Hi,
i'm looking for a way to get 9v regulated from a battery, ( i know some will say to just plug the battery  ) what i mean is sometime the battery is going down to 7 volt, but if i take the spyder power supply schematic, and i remove the bridge rectifier (db01), then plug the battery at this point before the 220uf cap, does the output after the 10uf cap will be 9v regulated or it will be the same voltage of the battery output voltage...

thank's

bent

[Papa_lazerous]

Ok A 9v battery starts it's life somewhere around 9.5v and as you point out gets lower, we can normally use them till they get to about 6.5-7.5v

You go plugging a 9v Battery into the spyder circuit you will get a whole lot of nothing coming out the other end.  the regulator itself shaves a few volts.  I think it needs about 2v headroom just to operate.  In short you cant get a nearly flat 9volt battery thats pumping out 7volts and make it still put out 9volts. 

there are circuits that let you get a higher voltage out a 9v supply.  But thats not what you are asking about is it?

why do you want to do this?  We regulate power supplies that run off the mains because we are producing a small DC voltage from mains AC and there is allot going on in there that you need to do to make it usable.  but a battery doesnt need regulating as its not coming from the mains and then through a power supply circuit. A battery is pretty much clean.  But a power supply has lots of nasty stuff going on that we dont like before its regulated

[bent]

a big thank you Papa_lazerous...... 

i was trying to find a way to keep the 9v steady from a battery to keep the headroom of the effect ...

bent

[Paul Perry (Frostwave)]

I sometimes just use an ICL7660 to double the battery voltage, then a 9v reg.
WARNING: the current drain from the battery will be doubled. But for a simple boost, that shoud not matter.
I don't do this for a booster, it's for when I make control voltage interfacing stuff, and I need a reliable fixed voltage.

[RaceDriver205]

was trying to find a way to keep the 9v steady from a battery to keep the headroom of the effect ...

The problem is power consumption. The fix is simple - use a bigger battery or use a plug-pack. You might want to try 6xAAA batterys (or 6xAA batteries) instead (if possible). Other wise there was a thread about making a super-long life 9V battery you might want to look at.

[Processaurus]

I sometimes just use an ICL7660 to double the battery voltage, then a 9v reg.

Thats crazy, Paul!

For the headroom issue, the problem isn't the voltage changing, its just that it gets too low.  Not knowing what your actual circuit is, its hard to guess what can be done about it, but in general modern rail to rail opamps can afford more headroom than the types more often discussed around here (and take less power), also you might be able to charge pump up the voltage and have the circuit run on 18v for mega headroom.  Though the average guitar signal is about only 200mV, maybe a volt or two on loud notes with hot pickups.

[Paul Perry (Frostwave)]

For the headroom issue, the problem isn't the voltage changing, its just that it gets too low. 

Can't argue with that.
My own application is for a device that outputs a control voltage over a defined range, and the way it works, the chip needs a fixed known voltage,
ideally 10 volts. Hence my approach.

But I still think, if someone wants to use a 9v battery in a simple booster & is worried about headroom, then why not double the voltage & be done with it. Or - and this is wild - use TWO nine volt batteries! voila, you have a voltage that changes - from 18 to 12 say - but never gets "too low".

Plenty of ways to skin the power supply cat.

[gez]

http://www.rapidonline.com/netalogue/specs/82-0782.pdf

Mouser sell them IIR.

[StephenGiles]

Use 2 x9v batteries and regulate that - simple!!

[Paul Perry (Frostwave)]

Use 2 x9v batteries and regulate that - simple!!

ROFL! If only I could take my own advice more often

[StephenGiles]

Use 2 x9v batteries and regulate that - simple!!

Sorry, I hadn't seen your post!

ROFL! If only I could take my own advice more often

[Paul Perry (Frostwave)]

No, I wasn't having a shot at you Stephen, I was giving myself a major "d'oh!" slap on my bald head because I actually went to a lot of trouble (9v battery + doubler + reg) for a one-off the other day, when I could have just used two damned bateries & ONE reg in a quarter of the time.

[StephenGiles]

No problem, I've done similar things myself!