power

[El Heisenberg]

I wnat to biuld bigget amps but am afraid of high voltage. When i breadboard any lm386 design more complez than the rub like a fetzer ruby or glen galassos amp it just squeels.

Anyway i want to biuld the tda2003 amp design. One of the ones from ggg.com or from craig andertons book.

When people biuld these so they just hook up the powrr like a stompbox and use a 12v dc adapter or somethinf?? Or in designs with a 12v regulator, this little transistor looking thing, do i just biuld the circuit and attatch a normal cord to it and plug it right into the wall? What about the designs with transformers? The transformer does all the work, i just need to hook up thr cors to the right leads eh?? Ive never worked with fuses either.

[SirElwood]

Or in designs with a 12v regulator, this little transistor looking thing, do i just biuld the circuit and attatch a normal cord to it and plug it right into the wall?

NO! You should never ever do this! You might injure yourself very badly or in worst case you might die.

You will always need a transformer.

[R.G.]

... do i just biuld the circuit and attatch a normal cord to it and plug it right into the wall? What about the designs with transformers? The transformer does all the work, i just need to hook up thr cors to the right leads eh?? Ive never worked with fuses either.

Please, please, please do some more learning before you start messing with anything which has an AC power cord. Your questions indicate a fairly complete ignorance (which is cured by learning!) of the dangers of AC line power.

We don't want you to die for your music, and there is a real chance of it if you go in the direction you've indicated.

[CynicalMan]

Or in designs with a 12v regulator, this little transistor looking thing, do i just biuld the circuit and attatch a normal cord to it and plug it right into the wall? What about the designs with transformers? The transformer does all the work, i just need to hook up thr cors to the right leads eh?? Ive never worked with fuses either.

Never work on line voltages unless you are absolutely sure you know what you are doing.

I think you should get a 12V wall wart then make a small regulator circuit as shown on this datasheet.

[El Heisenberg]

So in the schematic theres more i need to do? Theres more that isnt shown in the design? In the book he says just make sure the leads are wrappped in heat shrink and i put a fuse where it says to put one. Whats so dangerous if you dont short circuit?? Any suggested readin?

[R.G.]

So in the schematic theres more i need to do? Theres more that isnt shown in the design? In the book he says just make sure the leads are wrappped in heat shrink and i put a fuse where it says to put one.

Ever read or watch "The Sorcerer's Apprentice"?

The very word "schematic" means an almost irreduceable minimum of information to show how a thing works. Yes, there is more than a schematic to working electronics.

Whats so dangerous if you dont short circuit??

The AC power line is a high voltage which is high with respect to the voltage of the planet - the rocks, dirty, trees, plants and any object contacting them. If you happen to be touching anything that is grounded (yep, that is where the word "grounded" comes from), and also touch the AC power line, you can get a solid shock. The AC power line most commonly is set to trip breakers at 15 or 20 amperes. It only takes 20 1/1000th of an ampere to set your heart into fibrillation. Death follows. Guitarists have been killed permanently dead by touching another piece of electrical equipment while holding the grounded strings of their guitar. It doesn't get a whole lot more dangerous to one single person than death.

Short circuiting is the least of  your problems. The house breakers limit that.

Here's a question - what, exactly, does "short circuit" mean? 

Any suggested readin?

Horowitz and Hill, "The Art of Electronics"; "Radio Designer's Handbook, 4th Ed".

Alexander Pope said it first, and perhaps best, in 1709. http://www.phrases.org.uk/meanings/10400.html

[El Heisenberg]

That is what i meant by short circuit. Me shorting the circuit to ground.

Look maybe i came off as someone who has trouble changing batteries in a remote control but youre all makingthis sound like its voodoo. There cant be anything dangerous about this unless tge live ac wire touches something and shorts the circuit right?? Are you sayin i need to read a ton more so that i dont hook up the transformer baxkwards or something? I dont see how this 8 watt tda2003 amp that i see biult on so many web pages and you tube videos is such a hard thinf to biuld. The guts look straigh forward. I know how to solder. Directions are in the book: insulate live ac wires, groubd to one poin on chassi, seperate in and out leads. Wheres rhe strange voodoo im supposed to be afraid of??? These builds all seem so dinky and trashy!

After all this is the real advice "not to touch the live ac wire" Cmon!! Whats the secret! What am i supposed to be afraid of??!

[petemoore]

  Anyway i want to biuld the tda2003 amp design. One of the ones from ggg.com or from craig andertons book.
  When people biuld these so they just hook up the powrr like a stompbox and use a 12v dc adapter or somethinf??
  Following the directions specified in the schematic and related literature is a great place to start, questions about 'X" electronic parameter can invariably be posed more answerably with details involving exact schematic and circuit references.
  Or in designs with a 12v regulator, this little transistor looking thing, do i just biuld the circuit and attatch a normal cord to it and plug it right into the wall?
  Without even looking at the data sheet, I can assume you're refering to a 78XX or LM317 type, and the answer is...no.
  If that's what the directions say, then probably works that way, with the data sheet and directions + adequate reference to the circuit it will be applied to, perhaps we can find out if you've read these data sheets correctly.
  What about the designs with transformers?
  They generally require the use of a transformer, involve stepping AC, up or down, or creating a voltage/impedance ratio, also, they can be used to step AC supply voltage, or to match component impedances such as speaker:amplifier output, or couple signal stages...various other uses...
  The transformer does all the work, i just need to hook up thr cors to the right leads eh??
  No.
  I have not 1 clue what the transformer would be doing in this scenario, and assume 'cors' = cores...we just don't want that ''Brick Wall Experience'' [all those who experiment with electronics invariably have ''BWE's''], to involve a HV through exodermis connection, or worse.
  Ive never worked with fuses either....think of it as a 'weak pipe' connection, draw too much power the weak-pipe connection breaks...instead of all the other cool stuff that is much more expensive/harder to repair that a little section of pipe, the circuit may work fine without a fuse, that's one reason why using fuses is a good practice...when...[OT].
  There are better reads / diagrams / schematics / references available which are much more informative than what I can type here.

[El Heisenberg]

its overwhelming.

Ive spent the night  with craig andertons tda2003 amp on the breadboard. Ran it with two 6v in series. Its alright. Not sure im getting the full volume i can get. With ac i assume itll be louder?? I used a 6 ohm 15 watt speaker. Was alright till i added a tiny 8ohm speaker in parallel made it sound good. Then i added the fetzer valve circuit in front of it. Itll have the switchable gain resistors. And a volume control from the fetzer valve. This is how im planning on biuldin it. With socket for the input cap.

But i dont really want to run this on a ninev battery or a 12 wall wart. I wish i could post the schematic like its shown in the book. Its different from the schem on ggg.com cuz it shows the transformer in the schem. Also on ggg.com theres a pcb for this project tht looks like instead of the diodes an transformer set up, theres a spot for a bridge rectifier or wutever. Ive heard of these an seen then in radio shack but what do they do?? Could this be of use to me?? When i try to find info on my own i have to dig throught a bunch of terminology i cant understand. Its like trying to learn to multiply without having ever learned addition. Could someone tell me what i physically needto do to pull thiss off???

I am going to wire it up on perfboard and use heat shrink tubing to insulate the wires. I will keep in and out keads seperate an grouns everything to on point on the chassi which will be the negative terminal of the 1000uf cap that goes acrossthe v to ground. Use a fuse also. This seems like enough??

Please, specifically what could go wrong???

I cant post the links because iphones cant copy and paste.

[cpm]

yor wall wart already have a transformer, diode bridge, etc to get 12v out of AC mains, which is exactly what you are aking here. your circuit will sound the same whatever you are getting those 12v from, so you'd better look for a fix elsewhere if not happy with it

[El Heisenberg]

I just want to get this under my belt so i know how to do it and feel i can move forward to bigger rhings! Ive nevet done ac before. Ive only biult simple lm386 designs. ruby, litttle gem, noisybcricket, bridged versions for drum machine, bass and iphone. But i cant get more complex lm386 desings to work. Like the fetzer ruby, the practice man or the tube cricket. Ive done one tube build, the valvecaster. I built two actually. But those are the fanciest amps ive biult. I have ICs on the way from ebay, im going to try to build a few ms-2 amp clones. Hopefully i cant find good speakers... Ive only used transformers or inductors in stuff likebthe jawari and tycobrae octavia and passive guitar controls like varitone and mid scoop. I want a louder and amp and experience building with transformers and rectifiers and so on. So later I can take on a tube amp or something. Since i started this, ive found the only way i can really learn is to do it and ask questions along the way rather than read up a buncha articles in what might as well be in another language as far as i can understand them, and not absorbing any of it since ive never done anything!  After doing a project, working with transistors and ics and tubes and doing a few projects its easier to understand the texts.

Ive already bought the xformer from radioshack. And the fuse and fuse holder. Also shrink wrap and a heat gun. I just got back. The transformer isnt the right specs exactly:

Schem: 115 vac prim, 12.6 vac sec, @ 1A
What i got: 120 vac prim, 12.6 center tapped secondary, @1.3a

This wont be a problem will it? Just wire the fuse and switch (rated min. 120v) to the primary side and the diodes and everything. Ground to one spot on the chassi??

Id like to have something with a cool lookin transformer in it that ive biult. I dont want a seperate wall wart to lug around i wabt it all self contained with a cord running out of it all professional-like. Much morr impressive.

Ive already bought the parts and am going to start building this now. I cant think of anything going wrong. I wont be biulding it while its plugged in!  I made sure the caps were above 20 v. The switch is rated.


I think i have everything covered! What am i missing please let me know?? i  will chck back fromtime to time as i do take my time during builds. But i hope to be done today. I guess if i dont check back with the report, it mightve gone all wrong??? Naaaahh!

[Minion]

I would suggest if you want to make a Higher powered amp useing an IC you should Maybe look into buying a Kit (they are pretty cheap) , they generally come with very good directions and all the Parts needed and safety info to help you from not killing yerself .....

I have built several amps in the 15w to 150w range and have never even been shocked but I"m am stupid carefull .....

Cheers

PS: most power amp IC"s will not run from a single supply without major mods so in most cases you will be useing a Dual or center tapped secondary transformer...

[petemoore]

Ive already bought the parts and am going to start building this now. I cant think of anything going wrong. I wont be biulding it while its plugged in!  I made sure the caps were above 20 v. The switch is rated.
  Ok...
  Anything going wrong will think of you, you needn't worry about that.
  The large capacitors store DC voltage, I didn't quite catch the number, this stored supply voltage should verify that you've reduced it to 0.0vdc with a DMM before working on it, and the drain resistor should be left in until you exit, applies especially to supply circuits above ~30vdc.
  In addition of course to removing the AC supply source.

[El Heisenberg]

PS: most power amp IC"s will not run from a single supply without major mods so in most cases you will be useing a Dual or center tapped secondary transformer...

So that means the xformer i got is totally okay, right? I dont have the money for a kit.

[CynicalMan]

I cant think of anything going wrong. I wont be biulding it while its plugged in!

http://www.murphys-laws.com/murphy/murphy-laws.html

[El Heisenberg]

By that logic, anything that can go right, will go right. Why hasnt anyone else thought of this? Murphys law is rediculous!!

[CynicalMan]

By that logic, anything that can go right, will go right. Why hasnt anyone else thought of this? Murphys law is rediculous!!

It's a half joke but the point is that you should always plan for something to go wrong and do as much as you can to avert it. In this case you could do that by reading the articles and researching power supply construction until you are completely prepared for anything that can go wrong to go wrong.

[newfish]

As a one-time member of the 'Mains Voltage Flying Club', I can honestly say please be *very* careful if you're doing anything at all with mains.

Granted, I don't weigh much, but being thrown 20 feet across a room is *not* fun.

Nor is it particularly healthy.

Permissum constructum caveo - Let the Builder beware.

[El Heisenberg]

Still all ive heard is "you could get shocked". No advice at all! Nothing to help me not get shocked. I ask "what could go wrong?" the answer i get is: "things might go wrong"...! A little aggrevating that i cant get an answer here. I asked a specific question and cant get a specific answr. For instance

What were you doong when you got thrown 20 feet across he room? All you sai was you got shocked! Please please tell me what not to do!!! Please!

[R.G.]

(to the audience) Would all of you who are attorneys please quit reading now? I have no desire to unintentionally offend you.

(to El Heis) I'll explain why no one is telling you what to do and not do.

In the USA, there have been cases of people (let's call these party B) suing for and receiving huge judgements from others (let's call these party A) in similar circumstances. Party A may have told Party B how to clean a drain, steer a boat, stand on their head, any number of things. Party A may have been very careful to tell Party B what not to do to avoid getting hurt. But party B somehow got hurt - even if the hurt was purely mental, or emotional, as in they couldn't do it well enough and then felt embarrassed, or their girlfriend left them, things like that.

USA courts have awarded damages based on the silliest, most inane claims. As a result, I'm certainly not going to tell you how to mess with AC power wiring. Even if I did it perfectly, and you got shocked or killed, even years later in a different circumstance, even if you were doing things I'd told you NOT to do and not doing the things I had told you to do, some lawyer, somewhere could drag me into court and make me defend myself in front of a jury composed solely of people not smart enough to wiggle out of jury duty.

I don't know that is the basis behind everyone else, but it may be.

If you want training in how to work with AC power wiring, go get it from a live, in person trainer who's willing to take the legal risk.

You may be aggravated with me, or all of us over that; that's your right. But I think you might want to be aggravated by the lawyers and courts, and most certainly with your elected political heroes who have made this mess and can't be bothered to clean it up.

I do apologize for frustrating you, but in my opinion, it is not possible to type enough information here to train you to do AC power wiring safely, and I will not accept the legal liability for you ever getting shocked someday.  It is a mess. But I didn't make it.