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absolutjoann 18th October 2011 01:52 PM

Help a beginner out please! :>
Hi guys!

A buddy of mine built a ghettoblaster and that has totally inspired me to make one too... I've tried to read everything I can and soak in everything that's on the net but to no avail. Bear in mind I have no knowledge whatsoever about electronics. I'll be fine with the woodworking part though :P

So the questions I have are:

1) How does a boombox work? A diagram would be very helpful.
2) As a beginner, how should I start out?
3) I don't get how to calculate the volts and the ohms and currents etc. What do they even mean? Haha
4) Any other pointers?

Thanks in advance for any help, it'll be good if everything was just simplified, I'm a total beginner! I'm sorry if I have posted in the wrong forum, or if there has been a similar thread. I can't find an article that is not written in "audiophile speak" hahah!

Peace x

AndrewT 18th October 2011 02:05 PM

go to either Decibel Dungeon and/or ESP and find the articles you can understand initially. Once you have these in your head you can decide which direction you take next.

As an absolute beginner without background knowledge of the subject, the best you can do is adopt an already proven and recommended design and build it exactly as instructed in the build guide. If there is no build guide then forget that design.

sofaspud 18th October 2011 04:10 PM

The answers I have are:
1) Tough question because it can be answered on different levels. At its simplest, a music player has its output electrically amplified and converted to sound waves via a loudspeaker.
2) IMO, a beginner should learn the basic units and components and their schematic symbols. And answer 3)!
3) The relationship of volts, ohms, and amps are conveniently defined by Ohm's Law - V=I*R (voltage equals current times resistance). Power (watts) equals voltage times current.
4) I second the advice to find a proven design with good documentation. Work safely and don't be afraid to ask questions. And if you're ever unsure, don't apply power.

DF96 18th October 2011 07:33 PM


I've tried to read everything I can and soak in everything that's on the net but to no avail. Bear in mind I have no knowledge whatsoever about electronics.
You need to find sites which you can understand so you gain some knowledge. If you knew now how much you will need to learn it might put you off, so just regard it as the start of a long but interesting journey.

If you are starting from zero, then learn about battery and bulb circuits, DC and AC, series and parallel and Ohm's Law. Until you get this you won't understand any electronics sites.

absolutjoann 19th October 2011 02:07 AM

Oh I'm definitely a keen learner, I just didn't know where to start. Thank you guys, now I'm going to search those articles to gain the knowledge I need :D Any other articles anyone can recommend for me? Cheers!

Francec 19th October 2011 05:06 AM

If this is going to involve working with mains supply, think twice before attempting a project. Read ESP and other articles and if you don't feel very confident, my advice is DON'T DO IT!
I don't want to read about some woman "across the ditch" electrocuting herself. Remember, our countries have 240V mains supply and it doesn't just hurt if you get bitten.


absolutjoann 19th October 2011 09:14 AM

Hahahah Frank, I love how your name seems to describe exactly what you are... frank! :> lovvit. Anyway I appreciate your concern but if I was a fool I wouldn't be here to ask any questions would I? :P

As my first experimental project, I plan to use an old wooden speaker box that my mate has kindly given to me. It's dimensions are 580x410x210(mm). Is there a basic design that someone could refer me to? And what parts am I looking at getting at the moment? What else should I look for?


JoelS 19th October 2011 07:38 PM

Hi Joann,
When I was a beginner, I learned alot by taking stuff apart, and then later I started trying to fix things that weren't working. along the way I started learning the theory and also started making simple kits like Kits - Categories - SparkFun Electronics and Velleman nv. It took those many smaller efforts to build up to being able to design stuff.

as for your boombox, I have a couple questions of my own:
1) what will it play? the ghetto blaster I had played cassette tapes. will yours too? or will it be a radio? or a mp3 player? before anyone can produce a diagram you have to describe what you want more clearly.
2) how did your buddy do it? you could probably learn alot from just trying to copy what he or she did.
3) I second or third everything that was said above. be safe. make sure power is disconnected before touching anything. (ok, that wasn't a question)

I recommend that you buy a ghettoblaster on ebay, then take it apart and use the bits inside to build your box. Maybe you end up breaking it, but that's not so bad because then you will have to figure out how to get it working again. That kind of hands on training will teach you much more than you can learn from the internet.

by the way, electronics can be a kind of expensive hobby. don't be surprised if once your project is working you find that you have spent far more than it would have cost to buy a new boombox at the store. and you will need some basic tools like a solder iron and a multimeter.

good luck!


Francec 19th October 2011 08:30 PM

OK Jo, then perhaps you should now describe what you mean by ghetto-blaster?

Is it stereo, multiple speakers per side, powered by mains, have volume control as well as source selection or single source, and what sort of loudness do you want?

PS. Some people mistake being candid with rudeness rather than what it is; saying what you want and mean to say without the embellishment that may confuse. Some (read; many) people are such delicate little flowers that they seem to spend the large part of their life trying to find offense anywhere and everywhere.

And to what end? So they can say they are offended? Where is the sense in that? Plato found out the hard way but you would think we would have made progress over two thousand years.

benb 19th October 2011 11:25 PM

Dunno what's available overseas, but the ARRL puts out the "ARRL Radio Amateur's Handbook" every year. The first 100 pages are a condensed electronics course starting with "this is a resistor," what the formulas are, etc. Just about any edition since the '70's or so includes op-amps, which are commonly used in modern audio. The book of course covers a lot of radio ideas and radio frequencies, but these aren't totally useless in audio - sometimes audio equipment inadvertently responds to, or even emits radio frequencies, and it's good to know how to stop that with shielding and other things that apply to large portions of the electromagnetic spectrum.

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