battery question..

[kawayanstrat]

Is there any substitute for a 9v battery? I made a micro booster and i housed it in a small enclosure. Apparently it doesn't have a battery,but it runs on PSU. I want to power it with batteries but there's no more room. Can i use 3pcs/3v lithium watch batteries wired in series in place for the 9v batt?

Anyway,here's a picture of of the booster,so you can see how small it is.


Hope you guys can help.Thanks!

Mark

[Timebutt]

Wiring 3 3v batteries in series will work (once did it for something similar) but one thing you need to worry about is how much current they will be able to deliver? Might be that you have to change them more often?

[Mark Hammer]

Lithium coin batteries come in a variety of sizes and current capacities.  A trio of larger 3v coin cells takes up fairly little room and can easily be sandwiched in some otherwise useless available spaces in a chassis like the one shown.  Actually, a simple one-transistor booster is often one of the best circumstances to use that sort of battery supply since a great many of those types of circuits draw very little current.

Really and truly, the tricky part will be finding a way to hold them together in a dependable way that permits easy replacement (i.e., NOT electrical tape!).

[kawayanstrat]

Lithium coin batteries come in a variety of sizes and current capacities.  A trio of larger 3v coin cells takes up fairly little room and can easily be sandwiched in some otherwise useless available spaces in a chassis like the one shown.  Actually, a simple one-transistor booster is often one of the best circumstances to use that sort of battery supply since a great many of those types of circuits draw very little current.

Really and truly, the tricky part will be finding a way to hold them together in a dependable way that permits easy replacement (i.e., NOT electrical tape!).

I have battery holders that can hold 3/1.5v lithiums,i may just have to use two. BTW,i got the battery holder off a lighter with a led flashlight built in,it's fairly small and wiring both in series and fitting them is not a problem. I just want to know if it's ok to use them.

How much current do i need to power up this kind of circuit? First of all i got this circuit in GGG,and i reduced the size of the board to fit the enclosure.Here's the link http://www.generalguitargadgets.com/pdf/ggg_joam_lo_amz.pdf

Thanks for the replies!

[Timebutt]

The only way to find out is will be to take out your DMM and measure it
My guess is the LED will use up more current than the circuit itsself, unless you used a 'big' current limiting resistor?

[kawayanstrat]

The only way to find out is will be to take out your DMM and measure it
My guess is the LED will use up more current than the circuit itsself, unless you used a 'big' current limiting resistor?

I guess i will use a "big" current limiting resistor to give importance to the circuit.(goodbye laser disco lights )

[bkanber]

How much current do i need to power up this kind of circuit?

I think, in general, audio circuits draw around 5-10 mA (basically nothing. 5 mA out of a 9V battery gives you like 75 continuous hours of use.. alkaline 9V's are about 625 mAh, but you can't use all of that because once your battery is depleted to 5V or so, the circuit stops working as expected)

In general, red 5mm LEDs draw 30 mA (max-- 330 ohm resistor on a 9V supply gives you 27 mA-- that lights it up bright while preserving the LED's life). Red 3mm LEDs are rated for 15 mA max.

Obviously, different LEDs have different max current draws-- these are just typical figures.

Moral of the story: Your audio circuit draws way less current than the LED. I would suggest getting rid of the LED altogether if you want to power this with watch batteries. You should also check the battery's energy capacity (mAh) to get a better idea of how long these'll last you.

Burak

[kvb]

Aren't the watch batteries expensive as well? You might need so many you'll have trouble fittin them in anyway.
Why not just use a normal 9v battery with a jack attached. you could use any length leads and stash the battery anywhere on/under the pedalboard.

[R.G.]

I think, in general, audio circuits draw around 5-10 mA (basically nothing. 5 mA out of a 9V battery gives you like 75 continuous hours of use.. alkaline 9V's are about 625 mAh, but you can't use all of that because once your battery is depleted to 5V or so, the circuit stops working as expected)

Good reasoning, but there are some details issues. There basically isn't any "general audio circuit" current drain, except perhaps in the voting sense. They vary all over the map.

Carbon zinc 9V's used to be 160ma-hr, alkalines worked their way up to 300, and 460 for the "super" versions until recently when they have figured out how to get more into them. The moral - look it up for the batteries you use. It varies. A lot.

In general, red 5mm LEDs draw 30 mA (max-- 330 ohm resistor on a 9V supply gives you 27 mA-- that lights it up bright while preserving the LED's life). Red 3mm LEDs are rated for 15 mA max.

Obviously, different LEDs have different max current draws-- these are just typical figures.

Most panel mount 5mm LEDs in the T 1 3/4 package have a maximum continuous current spec of 20ma. This is based primarily on the amount of heat that can be removed from the package and how much heat the junction can take. 30ma is unusually high. Look up the datasheet to avoid smoking them. Running a 20ma spec'd LED on 27ma continuously is living dangerously for the LED. And what happens when the next ... um... bass player with a big grin on his face says "Hey, I bet this sounds mondo cooler on 12Vdc instead of 9V"?

And to mildly belabor a point, LEDs don't draw current at all - they'll eat whatever is available and die in the effort. No sense of self preservation at all. The designer must limit their current to be within spec to keep them from dying. An LED will provide current that is kind of linear with current, in that small currents give small light intensity, bigger currents bigger light intensity. This i used in multiplexed displays where the LEDs are pulsed up to maybe 100ma for a short fraction of the total available time so it averages out under the typical continuous current spec. 

What determines the LED current in pedals is more the light efficiency of the pedal - how many millicandelas per milliampere. Super-ultra-mondo bright LEDs can be plenty bright on 1ma or less. They can be blinding on 20ma. Old "standard" efficiency LEDs may be 1mC per ma, which is very dim.

Again, read the spec, find out how bright the LED is, adjust the limiting resistor accordingly. I use 4.7K for the LED limiter on many modern superbright LEDs.

[bkanber]

Carbon zinc 9V's used to be 160ma-hr, alkalines worked their way up to 300, and 460 for the "super" versions until recently when they have figured out how to get more into them. The moral - look it up for the batteries you use. It varies. A lot.

I have Enercell alkaline 9V's that are labeled 625 mAh-- I guess they really figured out how to cram more into them My rechargeable 9Vs are 250 mAh though.

Most panel mount 5mm LEDs in the T 1 3/4 package have a maximum continuous current spec of 20ma.

Good to know. All the 5mm LEDs I've ever used were either from radioshack or part of some cheap DLD kit, and they've all been rated 30 mA max.. But, certainly they vary all over the map. I couldn't agree more about looking up the datasheet; there's no situation in which that's not the best thing to do.

Burak

[zombiwoof]

What determines the LED current in pedals is more the light efficiency of the pedal - how many millicandelas per milliampere. Super-ultra-mondo bright LEDs can be plenty bright on 1ma or less. They can be blinding on 20ma. Old "standard" efficiency LEDs may be 1mC per ma, which is very dim.

Again, read the spec, find out how bright the LED is, adjust the limiting resistor accordingly. I use 4.7K for the LED limiter on many modern superbright LEDs.

R.G.

I asked this in another thread and didn't get a response - can you tell me why the LED in my Phase 90 is dimmer after I did the standard "Script" mods?  Mods here:
http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/MXR_Phase_90_to_Script.gif.html

I know what to do to make it brighter, I just want to know WHY it's dimmer after the mod.  It was an unexpected side-affect, and I want to understand the reason for it.

Thanks,
Al

[kawayanstrat]

But,will it work on lithium watch batteries even with the ordinary 5mm or 3mm leds?? Anyway,the circuit isn't "on" all the time.

[dschwartz]

why don´t you just do this:



you could even power 2 or 3 effects using parrallel outputs from the cell..

[kawayanstrat]

why don´t you just do this:



you could even power 2 or 3 effects using parrallel outputs from the cell..

Well,that's my second option.

[12milluz]

Totally OT , I know, I'm sorry, but what size enclosure is it? Where did you get it from?
It looks awesome!

[dschwartz]

why don´t you just do this:



you could even power 2 or 3 effects using parrallel outputs from the cell..

Well,that's my second option.

you can also try those little 12v batteries for car alarm remote controls..with a resistor you can make it go down to 9 v and save some current...

[kawayanstrat]

why don´t you just do this:



you could even power 2 or 3 effects using parrallel outputs from the cell..

Well,that's my second option.

you can also try those little 12v batteries for car alarm remote controls..with a resistor you can make it go down to 9 v and save some current...

Oh yeah,i forgot about that.Thanks a heap!

[soulsonic]

12v A23 batteries are tiny!
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=914

[kawayanstrat]

12v A23 batteries are tiny!
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=914

That was suggested by dschwartz. Now,if i could only find a way how to hold it.think...think...think.

[rikkards]

Duct tape? Velcro?
(semi-joking)

12v A23 batteries are tiny!
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=914

That was suggested by dschwartz. Now,if i could only find a way how to hold it.think...think...think.