How to power my Stella amp ?

Submitted by petey twofinger on Fri, 07/22/2011 - 01:55

i really do not care for 9 volt batteries and we have so many things that already run off of aa's . i was hoping to be able to run this unit off of a larger 12 volt sla cell i have here ? is that ok ?

how about a car battery or a deep cell , i have a few of those and we take those to the woods sometimes and have little jam sessions .its nice because i can recharge these and i don't have to worry about them running out all the time .

what about using an adapter , like a wall wort , is their an ideal voltage / milliamperage for this ? i know sometimes you get a hum when you use an adapter and that special ones , like the boss adapters for their pedals have a filter or something in them so they don't hum . is there a way i could implement a similar circuit in my Stella so i could use a generic normally "hummie" adapter and it would run quiet ?

what about methane ?

thanks .

Member for

11 years 5 months

John

Fri, 07/22/2011 - 18:58

If you're going to power the Stella amp with a car battery or sealed lead acid battery, the biggest issue is that while recharging the battery, or even a fully charged battery all by itself can exceed 12 volts. The opamp in the Stella amp has an absolute maximum rating of 12v, so it's not really practical to run it as is off of a car battery. It might work for a while but the opamp will fail much sooner.

If you're going to power the amp with a 12 volt sealed lead acid battery, I recommend changing the op-amp to a TL082 (available at radio shack for a few bucks). Then the absolute maximum voltage moves up to 16 volts and your battery will definitely stay under that voltage, as long as it is not being actively charged.

Another thing to consider is you probably want to put a filtering circuit in the power supply if you're going to plug the stella amp into an actual CAR. The electrical system of a car is very complex and can produce transient voltages at hundreds of volts for a few microseconds, among other problems. I HIGHLY recommend some type of voltage regulation if you're going to plug it directly into a car cigarette lighter.

If you come up with a way to use methane let me know!

Member for

11 years 4 months

petey twofinger

Mon, 07/25/2011 - 21:50

i got a tl082 from radio shack , it was like 2.19 cents . also swapped out r10 with a 470 ohm resistor per the notes in the instructions . i usually wire the rechargeable battery with a switching jack so if it is being charged it is disconnected from the amp circuit , or in other cases , i physically remove the battery and charge it . the test i did this evening i just used my one spot adapter which is 9 volts , this thing is LOUD for a mini amp . mind you i am using a 6 inch speaker . i'm wondering if there will be a noticeable difference when i slam it with 13 volts off that lil sla i got .

lately i have been removing voltage regulators from pcbs when i find em . i got a bunch of 5 volters and a few 9's but no 12's :( yet ...

acdcg400 (not verified)

Thu, 05/03/2012 - 16:08

What would be the approximate life/amp power with 4xaa batteries in series? What if 4xaa batteries were used in series/parallel for 3volts for 5400mA?

acdcg400 (not verified)

Thu, 05/03/2012 - 16:08

What would be the approximate life/amp power with 4xaa batteries in series? What if 4xaa batteries were used in series/parallel for 3volts for 5400mA?

Member for

11 years 5 months

John

Thu, 05/03/2012 - 21:31

I don't know what the battery life is with 4xAA batteries in series.

I had an old battery pack in my first amp, and because of the design of the 4xAA holder, it would come loose from the inside of the amp, short itself out, and blow out the batteries. This happened twice before I realized what was going on.

Since I put in a new AA battery pack and fresh batteries, I haven't run the batteries all the way down in the amp yet. Last night I played a ton of jazz (about an hour's worth) at a fairly high volume and that didn't even put a dent in it. I put another loud hour on it today. I know I need to just run a test, straight through, but I haven't figured out how to do that without driving my wife/kids/neighbors nuts.

I don't think I would recommend 4 batteries, two pairs in parallel for 3 volts total. It'll be a little bit before the voltage drops, but not that long, and when the voltage drops below 3, then it's going to stop working.