#1
This is now the thread I will keep the progress of my amp build in, if any one wants to look at my progress or anything. I don't want to be a bother, so I won't make another thread.

A very small, solid-state, battery-powered amp?

I have a small, 8-ohm 0.5 watt speaker, so it'd be best if it was designed with these specs in mind.

I would just like to do this as a fun little project, and would like recommendations from people, if they've tried a certain schematic, and it was good.

Thanks!



SlayingEdit: As of 06/13/10

Here's where I'm at so far:

I ordered the parts, they should be here in a couple days.

I have found what I will be casing it in: A shoebox I had lying around.

I will be ordering a 4-inch, 6-watt 8-ohm speaker.

I will be wiring in an on/off switch, and a low-power LED to indicate whether it's on or off.

I will be using a LM386-N3 (I think that's the right name...) as the op-amp, as opposed to the low-power LM386-N1 sold at radio shack.

And I have done a good amount of research on this, and have learned a lot from it, and from the people on here. Let's hope it works!

Last edited by SlayingDragons at Jun 13, 2010,
#3
look up CMOY's head phone amp... or just google.. theres lots of stuff i think runoffgroove might have something
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#4
The Noisy Cricket

How big is the speaker, diameter-wise, and did you buy it, because I'm looking for somewhere to buy a 3-4" diameter speaker, and good luck with w/e you decide to do with it.


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RBY CYOA
Last edited by MonkeyLink07 at Jun 2, 2010,
#5
Quote by mattvl


Ah, thank you very much!



Quote by MonkeyLink07
The Noisy Cricket

How big is the speaker, diameter-wise, and did you buy it, because I'm looking for somewhere to buy a 3-4" diameter speaker, and good luck with w/e you decide to do with it.


Hmm, this is cool too. I think I'll start with the ruby, though, as it's a little more basic.

And, it's like 2.5 inches, estimating. And no, I didn't buy it, it came from a couple scrap electronics I had lying around. :/

Last edited by SlayingDragons at Jun 2, 2010,
#6
Oh, I have a question about the ruby amp: (And it has massive amounts of n00b in it,)

What should I ground the circuit to? Just the casing, or what?

Sorry, there's a reason I picked such a simple project.
#7
everything (even the case) all goes back to the (-) terminal of the 9v battery.

sent you that MS-2 schem btw. it's more involved than the Gem and Ruby amps though. It might sound better too. idk though, never heard one.
#8
I just built one of the rubys. I am waiting though becasue I need a 9v battery plug thing.

My soldering is awful....

Time on earth is like butterscotch; you really want more, even though it will probably just make you ill.



Certified lurker
#9
Quote by Invader Jim
everything (even the case) all goes back to the (-) terminal of the 9v battery.

sent you that MS-2 schem btw. it's more involved than the Gem and Ruby amps though. It might sound better too. idk though, never heard one.


Hmm, definitely cool, although I'll start with the Ruby amp, for the sole purpose of simplicity. Afterwards, I'll try the mini-marshall, and slowly work my way up in project difficulties.

Oh, and thanks, I didn't know that. I'm still pretty n00bed up in this, I know I probably annoy just about every experienced builder on here. :\

Just another question, I'll be asking questions throughout this thread, if people will be willing to answer: In the schematic for the Ruby amp, it calls for a component that is rated at 47n, what type of component does this refer to? Some sources I've found have said it's a capacitor, but I can't find any that use this type of measurement...

Last edited by SlayingDragons at Jun 3, 2010,
#10
its a capacitor, yeah. 47nF means 47 nanoFarads. nanoFarads is supposedly mostly use in europe but alot of people use it constantly just to avoid lots of decimal places (like typing 6.8nF instead of 0.0068µF). a nanoFarad is a thousandth of a millionth of a Farad.

47nF is the same as .047µF. µ is the greek letter "mu" meaning "micro". many times you'll see it written as "uF", "mF", or "mfd". they all mean microFarads, which is a millionth of a Farad.

another prefix you'll see alot is pF, meaning picoFarads. its also called "µµF", "uuF", or "mmF". these all mean micro-microFarads since a picoFarad is a millionth of a millionth of a Farad.

You can see how tiny the values of capacitance we need in electronic circuits. The only places you'd use values of 1 Farad or higher are in car stereo systems and computer memory circuits. I happen to have a 50F cap and it holds an insane amount of charge. normally a cap discharges instantly if you short the legs together with no resistance between them but this once takes 6 whole seconds to bleed off 1.5 volts (it's only rated for 2.5 volts).

Hope this doesnt confuse you too much
#11
^Thanks, that confused the heck outta me.

Anyways, here's where I'm at so far:

I will be ordering the parts soon.

I have found what I will be casing it in: A shoebox I had lying around.

I will be ordering 2 new, unused, undamaged speakers, rated at 1 watt per piece, 8 ohms each, and will be wired in series.

I will be using an old t-shirt as the grill cloth, and will use the metal from a couple altoids tins to make the backing for the knobs. All of which are aesthetic.

I will be wiring in an on/off switch, and a low-power LED to indicate whether it's on or off.

I will be using a LM386-N3 (I think that's the right name...) as the op-amp, as opposed to the low-power LM386-N1 sold at radio shack.

And I have done a good amount of research on this, and have learned a lot from it, and from the people on here. Let's hope it works!

Last edited by SlayingDragons at Jun 6, 2010,
#12
Quote by SlayingDragons
^Thanks, that confused the heck outta me.



I got all the parts for an MS-2 build so if you want I can tell you if it's worth building.

fyi, the only differences in my build will be an NPN germanium transistor for the OD channel and the 1µF and 100nF capswill be tantalum instead of electrolytic and poly film. Germanium transistors sound better to my ears (i used to think it was mostly hype) and the tantalum caps are alot friendlier to lows and highs than electrolytics. Not sure of the differences for poly film, but im gonna find out.
#13
Quote by Invader Jim


No, I meant that is was confusing me, and you cleared it up for me.

I got all the parts for an MS-2 build so if you want I can tell you if it's worth building.

fyi, the only differences in my build will be an NPN germanium transistor for the OD channel and the 1µF and 100nF capswill be tantalum instead of electrolytic and poly film. Germanium transistors sound better to my ears (i used to think it was mostly hype) and the tantalum caps are alot friendlier to lows and highs than electrolytics. Not sure of the differences for poly film, but im gonna find out.


Hmm, interesting. I may follow your example, just for the heck of it.

I'm sure it's worth building, but I'm starting with the ruby. I'll build the MS-2 sometime later.
#14
well just fyi, NPN germs are hard to find these days and cost alot (as far as transistors go). i think smallbear stocks some.

that 6213 chip is my only worry atp. the caps and transistor im using should do alot for the sound but it all ends up going into that power amp chip. if it isnt to my liking i'll try a bridged 386 configuration instead, like the little gem 2 on runoffgroove. The N-4 can put out about 1W (.7W min.) all on it's lonesome, so I should get 1.4W to 2W out of a bridged design. the 6213 is 1W iirc
#15
Quote by Invader Jim
well just fyi, NPN germs are hard to find these days and cost alot (as far as transistors go). i think smallbear stocks some.

that 6213 chip is my only worry atp. the caps and transistor im using should do alot for the sound but it all ends up going into that power amp chip. if it isnt to my liking i'll try a bridged 386 configuration instead, like the little gem 2 on runoffgroove. The N-4 can put out about 1W (.7W min.) all on it's lonesome, so I should get 1.4W to 2W out of a bridged design. the 6213 is 1W iirc


aaannnd this is where you lost me.

Oh, another Q: Could I use a capacitor rated at 10v on a 12v circuit?

Probably a dumb question, but, you know...
#17
Quote by Invader Jim
no. gotta be higher than the voltage of the circuit.


Ah, okay. I thought that was more than likely the case, but I wanted to make sure. >.>
#19
Quote by Invader Jim
yeah, if you over-volt a capacitor, it can explode.


Whoa. 0.o

While it sounds kinda cool, it's not what I'm going for right now.

Anyways, I've got my parts list together: I'm getting everything from digikey, and the grand total, including shipping and tax, is $40.46.

It's a little more then I was hoping for, but I'm ordering enough parts to build 2 amps, so 'twas be 'spected. And I'm ordering a new set of speakers, the one I have now really just kinda sucks, so that added a good bit to it.

Anyways, should be cool, I'm really excited to build this!

#20
yeah, you ever notice how the tops of big caps are scored with a Y or K shape? Thst's so if it explodes it'll pop the top instead of becoming shrapnel.

I've been doing this for 10 years and i still get excited over my builds.

edit: holy crap, i just finished making a layout pic of the MS2 and could actually squeeze that whole amp onto a piece of perf the size of smallbear's smalles size yuss.
#21
Quote by Invader Jim
yeah, you ever notice how the tops of big caps are scored with a Y or K shape? Thst's so if it explodes it'll pop the top instead of becoming shrapnel.

I've been doing this for 10 years and i still get excited over my builds.

edit: holy crap, i just finished making a layout pic of the MS2 and could actually squeeze that whole amp onto a piece of perf the size of smallbear's smalles size yuss.




And yeah, I've been building circuits for over 2 months now! So I have very little experience.

This is my 2nd build, my first was a distortion pedal, and I believe the only reason it didn't work is because I used the wrong type of transistor... Ah, well...
#23
Quote by Invader Jim
maybe you just mixed up the leads?


Nah, I double checked that. The guy that made the schematic for it told me I may have used the wrong transistor, so I'll just pick up the right one sometime, and rebuild the circuit.
#25
Okay, I just ordered all the components today, they should be here in a couple days.

I have the entire thing planned out, and I'm really hoping to get this working well. I've learned a lot from it, and it definitely got me interested in amp and gear building.

#26
Okay, this little project is officially finished!

I got the parts today, and, naturally, proceeded to assemble without further delay. It took a little to put together, and to work out a couple small things, but it went pretty well, almost no problems whatsoever.

The result? Picture time!



It sounds pretty good, although the overdrive gets a bit cheesy at the max gain. It's actually a bit too loud, with the 4" speaker I opted to use, and I couldn't get the volume pot to work, it doesn't lower the volume. It really just stands there and looks pretty. I'll have to figure it out sometime... But the gain pot works nicely.

This amps gets awesome cleans, just about crystal clear. It's awesome. The amp overdriven is pretty cool with a little sprinkled on, then gets a little more 'meh' as you go up. May be because I couldn't find the JRC386, which is supposed to sound better than the LM386. Ah, well. I'll get a sound demo some time.