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Components advice for a noob
http://diyaudioprojects.com/Forum/viewtopic.php?f=5&t=521
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Author:  El Capitan [ 17 Feb 2009, 10:37 ]
Post subject:  Components advice for a noob

I am new to building my own stuff, and have some questions regarding what resistors, caps, ect. to buy.

First off, on the scematics I see, there is no wattage rating for resistors or caps, but when I search for them on the internet (I was told digikey was good) I needed one, is there a calculation that I can do with the Farhads and ohms to find how many watts I need?

Also how do you guys go about choosing what opamps, transistors, tubes, ect. to use?

Finally, is there a difference in quality between more mundane parts like resistors?

Any and all advice is appriciated,
Alex

Author:  Gio [ 17 Feb 2009, 19:33 ]
Post subject:  Re: Components advice for a noob

Hi Alex,

You can apply Ohm's Law to calculate what power is dissipated across the resistor.

Most will have their own personal preference as to which parts sound best. If you are just starting up, it would make sense to use generic and common parts until you develop your own preference.

Hope this helps,
Gio

Author:  El Capitan [ 18 Feb 2009, 00:23 ]
Post subject:  Re: Components advice for a noob

Thanks Gio,

So it sounds like that for now, Radio Shack resistors and caps will be good, but the schematic I found for my first build (the Very Simple Phono Stage on RJM audio-the name sounded good for a starter) calls for an op amp and voltage regulators in the circuit, and a transformer and some diamond shaped thing I dont recognise in the power supply. If you want to take the time to visit the site, I've posted a link to it below. Where do I go about finding these types of parts?

Thanks for your time and knowledge,
Alex

Author:  Gio [ 18 Feb 2009, 00:52 ]
Post subject:  Re: Components advice for a noob

Hi Alex, you forgot the link.

Is this the project: http://www.geocities.com/rjm003.geo/rjm ... _pho5.html

Author:  merlintso [ 18 Feb 2009, 09:45 ]
Post subject:  Re: Components advice for a noob

The diamond shaped picture in the schematic next to the transformer dual outputs, is a rectifier.
Rectifier converts AC to DC.

This VSPS build looks somewhat difficult! Good luck!

Author:  RiGuy [ 18 Feb 2009, 15:11 ]
Post subject:  Re: Components advice for a noob

Merlintso, Trust me you could build that to :) It puts together just like the schematic looks. Some projects are nice in that the schematic actually ends up looking like your final product.
Ri

Author:  El Capitan [ 18 Feb 2009, 22:03 ]
Post subject:  Re: Components advice for a noob

Oops i did forget the link, but yes, that is it.

So any way, are there specific sites to order rectifiers and transformers and op amps from, and if so what are they.

Also, is there any advantage besides organization to using circuit boards? because from what Ive read on this site, it sounds complicated and acid involving.

Thanks again.

Author:  Gio [ 18 Feb 2009, 23:03 ]
Post subject:  Re: Components advice for a noob

Hi El Capitan,
That is a very simple design that should be easy to reproduce on a protoboard. Time spent up front planning the layout will be worth the effort when you come to building it.

For the resistors, I would use generic metal film and 1/4 or 1/8W will be fine. Carbon film is also an option, but they are not as quiet as metal film and cost the same.

For the caps, polypropylene, mylar and polyester are suitable choices. Just note that some can be physically large in size. Again, generic will be fine, especially to get you started. Save trying out boutique caps for later.

For the opamps, OPA2132, OPA2134, NE5532 or NE5534 are all reasonable choices that will work well and won't break the bank. I would suggest the OPA over the NE, but that is my personal preference, NE is fine too. If you can't find those, even a TL082 from Radio Shack will be fine (make this your last choice, again my preference). You will find opamps all over, DigiKey, Mouser, perhaps even a local electronics shop.

If you want to make this real simple, you can forget about the power supply and use two 9V batteries as shown on Mark's GWado / CMoy Headphone Amplifier. Simple can be very good. ;)

The RJM page is well documented so give it a good read and feel free to ask for help.
Cheers

Author:  El Capitan [ 19 Feb 2009, 18:01 ]
Post subject:  Re: Components advice for a noob

Thank you for your help.
Im sure Ill be back with more questions.

Alex

Author:  El Capitan [ 19 Feb 2009, 18:57 ]
Post subject:  Re: Components advice for a noob

Hey what a surprise, I have found a new question already.
Will this transformer work it? it looks like it has the correct specifications: US voltage, two 12va secondary windings, not too expensive. But it also has not one but two 115va primary windings. Is this a problem?

I remembered the link this time, two.
http://www.parts-express.com/pe/showdet ... er=122-600

Thanks again, Alex

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