Instructables
So you're trudging through the woods, just you, your guitar, and your amplifier. Suddenly, a large bear approaches and you have no option but to shred him with your insane guitar skills! (running is not an option, as everybody knows that you never run from a bear, you fight him)

Unfortunately, there are no power outlets within sight! Steeling yourself for your grisly demise, you try to play a song acoustically.. but it's not loud enough. As the bear reaches over you with his jaws, you wake up. And are aware of the need for a portable amp. But, since you are a musician, you are obviously at poverty level and can't afford a small portable amp. So what do you do? You build one, for free of course, out of everyday parts.
 
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Step 1: Collect your materials.

For this project, we will actually be using an Ibanez bass amp, and a bass guitar (my electric guitar isn't in yet, and the amp is obviously far too big to be portable, and this was just laying around).

Also, please keep in mind that this is a simple proof of concept project (proof for myself), and is in no way safe, complete, stable, smart, etc.

Basically, what we are going to do, is take this combo amp, and run it off some batteries, to make it portable. Why? Read the intro ;)

So what you need (and you should be able to find this anywhere in your house, friend's house, roommates gym bag, etc.)

Supplies:
2x9v batteries
2x9v battery clips
Wire (thicker is better, try 10awg)
Alligator clips (preferably 4)
Switch (SPDT)
Duct tape
Amp
Guitar
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MarkTBScyesterday

To be honest, I'm amazed two PP3 batteries would power this amp at all! The standard Alkaline model is specc'd with about 500mAh capacity and they're designed to discharge over 20 hours, giving you 25mA draw. At 18v that's almost 0.5 watts for the whole system. If you try and draw at 100mA then you'll get maybe 1 hour out of the batteries and they'll be burning hot. Even that will only get you 1.8W. I'd switch over to 3 4.5v 4Ah Alkaline lantern batteries. Drawing at their rated current of 200mA, you'll have almost 2.5W to play with and the power will last for over 10 hours. Also they're not too heavy and you're not messing around with Lead-Acid or Lithium.

muddog157 months ago
Also. Little deer feeder batteries are light.
muddog157 months ago
12v battery works better. Or maybe a voltage regulator.
PCvsMac6 years ago
Hello again :) Something that has been confusing me: Would it simply not be easier to have, let's say a 12V Lead Acid battery (from a car, maybe) and simply strip a male computer cable (the end where it plugs into the power supply, which I believe in America is 2-prong 120V) and attach some alligator clips to it and plug the other end (when you want to plug your amp in) into the power feed of the amp?
finfan7 PCvsMac6 years ago
the problem there is weight. An amp can be very dense. (high weight to volume ratio) The same can be said for a car battery. So the weight of the car battery would easily double the weight and volume of the amp. That would not be conveniant.
PCvsMac finfan76 years ago
That is fair enough then. But would it still be possible? And how about using a really small car battery?
mac won again
ac1D ElvenChild3 years ago
You think?
ElvenChild ac1D3 years ago
I know
finfan7 PCvsMac6 years ago
It would work but I have never seen any small car batteries. I had a better idea though. I saw someone say somewhere that they had a circuit that would switch the power source to the next battery when the first one got too low. I thought it should be combined with a set of rechargable 12v camera batteries. Total price equal to a car battery but with longer battery life and no replacement costs within the near future.
use a small sealed lead acid battery like what is used for backup power in an alarm system. I have some 12 volt 7AH batteries and they only weigh about 5 pounds.
PCvsMac PCvsMac6 years ago
Also, someone please reply! Thanks, I hope to hear from anyone soon!
it is still winning
mac won
cody3164 years ago
Thanks to you, i can impress chicks ANYWHERE now! nice instructable dude, and ill thank you ahead of time in case i ever get into an encounter with a bear!
arcane2rox4 years ago
Legenary intro to the instuctable! I have to say that I am a musician along with several friends of mine and we are all at poverty.
northconnor4 years ago
Nice job. Does it go to 11?
scott!5 years ago
Dude, nice intro, that cheer'd me up! :D lol
RelaxedSoup5 years ago
Maybe you could try using rechargeable batteries, and when the amp is plugged in, have the batteries charge. Perhaps you could also make a bypass switch, that, when plugged in, will let you switch between charge and battery bypass... hmmm. My old 15 watt amp is 500 miles away, when I get it back I'm definitely going to try that. Also, nice instructable, if I had a nickle for every time I've had to fight off a bear with my guitar...
ironsmiter7 years ago
IMHO, 15 min isn't nearly long enough :-)
At most, those standard 9-volts are gonna give you 1200 mAh (for Lithium-Ion), more likely 560 mAh and that's not much. Rechargable Nicad "9-volt" batteries produce closer to 7.2 volt, putting you at 14V, with the added bonus of being rechargable... but with a lower total capacity(about 120 mAh) but that could be fixed by running in serial and parallel.
If the circuitry can run at 12 Volt... use a pair of 6volt lantern batteries.. or better still, a "sealed lead-acid" battery out of an old UPS, or new from the store...

"(a)add to the already heavy weight,"
yep, but 5 pounds for the 8Ah battery i found for $12

"(b) cost more than amp itself"
how cheap was that amp, and where can I get one? ;-)

"(c) most likely leak at some point."
Eventually, those 9-volt batteries are gonna leak too....
Modern sealed batteries have very little chance of leaking and can be safely used in any orientation...just don't cook them, or they'lll off gas and that's bad for your circuits.

"I've been meaning to look into some higher voltage batteries"
even with the 2x9volt.... you SHOULD try to use some kind of voltage/amperage regulation... even more so, with bigger, more expensive batteries...

Would make a FUN collaboration...
Here, I'll start :-)

And consider putting the batteries down, on the bottom of the case if the back panel is removable. it'll make it seem lighter, through better load balancing.

use a 12-volt rated switch(like the one you're using now :-) and mount it on the case... splice into the 13volt wires, sending one straight to the battery, and the other to the second battery terminal, by way of the switch(interrupts the circuit when "open") ...
Now, when it's plugged in, 13 volt goes to the amp as normal.... when the power goes out, you flip the switch, and presto... battery backup power.

If you get really funky, Remove the transformer completely...
in it's place, wire in a "battery tender"... and of course a battery.
Now, when it's plugged it, it runs off the combined might of the trickle charger and the battery... when it's OFF, but plugged in, the battery is charged/maintained at peak readiness... when It's unplugged, throw the switch to ON, and rock out!

Since it's all ICs... and I see what appears to be on-board voltage regulation, you could probably drive it with anything from 11.5 to 18 volt(at least that's what the ICs in my radio are rated at), and let the beastie take care of itself.

And for heavens sake, GET SOME ELECTRICAL TAPE! $1-2 a roll el-cheapo from the store is just fine... or, if you wanna get spiffy, a $5 bag of heat-shrink tubing from the local mothership... er, I mean Radioshack... or wherever. If you're gonna be hacking electrical stuff... electrical tape, and a soldering iron will be your friends :-)
The smallest amp I have is a Fender Eighty-Five. I was looking at the schematic, and the most DC voltage on the mainboard is 40 VDC. That'd take a minimum of 3 12v batteries to match-that's a lot of weight for an amp that is already kinda hefty.
dang.. posted too soon... Tower Hobbies has a 4.5Ah 12V Starter Battery and it's matching charger for about $10 a piece... would add a total of 5-6 pounds for both, plus the wiring...
uzerzero (author)  ironsmiter7 years ago
I'm gutting everything out of the inside that I won't need (120V input, voltage regulator) which lowers the weight quite a bit. I tested with a 12v wallwort, and it will run off 12v. So that battery and charger from tower hobby should work pretty well. However, I'm moving soon and really can't spend any money, but if somebody wants to donate a little bit, that would be great! As for the charger, I'm thinking of perhaps building a breakaway cable, and coiling it up inside the amp. Either that, or put everything, adapter and all, inside the amp, and run an extension cord. As for the price on the amp, I received it as a gift as part of a combo set. It's retail price runs at around $70 though. But you can find any number of similar amps for $30-$40. I underestimated on the price. Until I either muster up enough money to purchase that battery and charger, I'm just going to keep the 9V batteries in there for now. Makes a good conversation piece :)
uzerzero (author)  ironsmiter7 years ago
Thanks for the good tips man. I do use electrical tape 99% of the time, but I left my last roll on my windowsill, which rendered it completely useless. I'm republishing this to a collaboration, so any ideas for department stores that would carry any products, etc., would be great :) On another note, my guitar comes in this week. :)
jkoznek5 years ago
Check out http://www.goldmine-elec.com/ . They have solar panels. I was thinking a 20v solar panel and some rechargeable 9v. I think I saw a 20v panel there 12" x 9". That could be used as a "back panel" to the amp with the circuit inside. You get the compact size and weight plus a renewable energy source. Or...you could go to goodwill and pick up some old computer speakers that are 9v and use a 3" x 9" 9v panel and a 1/8" to 1/4" plug converter to plug into your guitar... not as loud and won't be able to hold the same kind of bass but it would work w/out frying your amp :P
backcountry7 years ago
You want a really portable amp? Try one of these:
http://www.smokeyamps.com/
they look god awful
I bought one about a year back, they give off about 1.5w. They sound terrible, even with a quiet guitar
snotty6 years ago
Need more details for transformer pinouts. Can anyone point us to some general instructions for bypassing different kinds of transformers? That would be awesome! I really like this project but I'm having a hard time adapting it to my "RK 20rc Rocktek" amp. I want to put it on my bicycle for critical mass rides and maybe even make it pedal-powered later. -Yeah
Khurs snotty6 years ago
I just pulled mine out then linked the cables. This allows the switch to work and reduces the weight greatly
timgray6 years ago
It did save me from several bears, though
timgray6 years ago
I did a similar thing to my samick bass amp, and cooked it... So I checked the voltage on the back of the transformer and got 12 volts, sounds good right? I probly should have check to make sure it was 12v DC, It wasn't. It lasted a while but the sound quality and volume gradually deteriorated until I ended up with silence. Very sad but it was cool while it worked. Anyway I just built a new rig, perhaps I'll tell y'all about it later...
PCvsMac7 years ago
DUDE! I created my first Instructables! I have made myself a guitar amplifier out of spare parts, running from a 9V battery, and yes, it is portable. I am not sure if it works, but I think I am on track. Let me know if I have made any mistakes or recommendations, Visit it here. http://www.instructables.com/id/E703YRCF3B2TTGF/
You took it down...
Yeah, sorry about that. Apperently I needed to take it down as it did not contain pictures. Anyway, it was not a real isntructable and it did not work, so I removed it. I appologise for any inconvienice caused.
pinkpooj6 years ago
I have a Roland Micro Cube that runs on 6 AA's, or a cable. It lasts for about a week.
ipatch6 years ago
hey man just connect a car battery to an DC converter and plug it in its easier and lasts longer
shaunak ipatch6 years ago
A car battery supplies DC power.. why a converter? But really, those square batteries have a worse life than 1.5V D cells. Ps: you could also try Ni-cd batteries.
ipatch shaunak6 years ago
WOW my bad i ment an AC Inverter! Good Job Ian way to say the complete opposite... my bad...
LasVegas7 years ago
This had the potential of being a great instructable; Had you taken the time to experiment, refine the process (alternate battery choices) and present a finished project rather than the results of your first attempt. As it is, it's rather lacking.
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