Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › Cigar box Apheared 47
New Posts  All Forums:Forum Nav:

Cigar box Apheared 47 - Page 2

post #16 of 58

The capacitor on pin 8 is a film type capacitor.

It can be a "through hole" or a "SMD".

You can use the same cap in the power supply if

you wish. The ones I use are 1 uF @ 63 volts just

because it is a common value.

post #17 of 58
Thread Starter 
Quote:
Originally Posted by Avro_Arrow View Post

The capacitor on pin 8 is a film type capacitor.

It can be a "through hole" or a "SMD".

You can use the same cap in the power supply if

you wish. The ones I use are 1 uF @ 63 volts just

because it is a common value.



Oh I meant the capacitor that's on pin 8 as the power supply cap. The other one is the same value but in the amp itself, between the volume pot and the opamp.

post #18 of 58

OK, here is some terminology for you.

The cap that goes after the volume pot is called the "input

cap" and it's job is to block DC from getting into your amp

from your source. The small value film cap on the power supply

pins for the op amp is call a "bypass cap". It's job is to keep

high frequency noise from invading your op amp. The large

value electrolytic caps on the power supply pins for the op

amp are the "Rail caps". Their job is to provide the extra current

that may be need to the the op amps better bass and dynamic

impact.

 

Does that help out?

post #19 of 58
Quote:
Originally Posted by T.B.N. View Post



Quote:
Originally Posted by Avro_Arrow View Post

There are two versions of the TLE2426.

One is in a package like a small transistor with three pins (TO92).

The other is in a package like an op amp with 8 pins (PDIP-8).

The 8 pin version is better than the 3 pin version even though

they are supposed to be identical.  The extra connection on the

8 pin version is for a noise reduction capacitor.
 



I see... and with the 8 pin version, only 4 pins are used then, 1,2,3 and 8, which has the capacitor on it. A quick question about the capacitors: the schematic calls for a 1uF capacitor, one for the power supply and one for the amp section. Can I use the same type of capacitor for both, or are there different requirements? I'm going to use 25V rated caps for the whole thing I think, because the amp will run on ~18V power supply.


Yes you can use same type of capacitor for them, I would suggest high quality polyester caps. But really I don't think there is much difference in using TLE2426 with or without the capacitor. It can't harm though.  25V is fine!

post #20 of 58
Thread Starter 
Quote:
Originally Posted by Avro_Arrow View Post

OK, here is some terminology for you.

The cap that goes after the volume pot is called the "input

cap" and it's job is to block DC from getting into your amp

from your source. The small value film cap on the power supply

pins for the op amp is call a "bypass cap". It's job is to keep

high frequency noise from invading your op amp. The large

value electrolytic caps on the power supply pins for the op

amp are the "Rail caps". Their job is to provide the extra current

that may be need to the the op amps better bass and dynamic

impact.

 

Does that help out?

 

That helps enormously. Now I know what they're actually there for.

 

So the rail capacitors should be electrolytic. So Aluminium Electrolytic is fine?

 

The small caps, the bypass and the input caps, should be film. Any recommendations for the type? Polystyrene? Polypropylene? Paper? I'm just looking at the options on Newark.

 

Edit: Didn't see your post before spacehead. I'll get polyester then. I don't know what is high quality except for the higher priced. Maybe I'll just use the 3 pin TLE2426 as it fits nicely in the layout that's on the A47 website.


Edited by T.B.N. - 12/6/10 at 7:56pm
post #21 of 58
Thread Starter 

Another quick question: Can all the resistors be ~1/8-1/4 watt rated? I know that's enough for the CMoy, just wanted to check.

post #22 of 58

Yes, 1/4 watt is commonly used but really 1/8 is all thats needed.

Most people feel that 1% metal film resistors give the best sound.

post #23 of 58
Thread Starter 

Great that's what I thought. The larger resistors (47Ohm) might be wire-round, but I'm sure it'll be fine for this project.

 

The last part I'm having trouble with is the proto-board. Ideally I'd like a perforated board with individual copper pads for each hole. I'm ordering from Newark, and it's hard to tell what the board is like because the pictures are not necessarily of the exact item. I'm not sure what I'm looking for, or what's a "good" board. It's quite possible I'll be resoldering the parts a couple of times to get it right. Any suggestions? I'm also going to get a radioshack board that was suggested on the A47 site, but I may change the design slightly so I thought I'd ask about single hole boards.

post #24 of 58

I wouldn't use wire wound, the added inductance will be a problem

 

cheers

FRED

post #25 of 58
Thread Starter 

Ok, now theyre all metal film.

 

About the power supply, I'm going to get a wallwart at around 18V, how much current will the amp draw? Less than an amp?

post #26 of 58

500mA should do nicely.

Higher is OK too.

I wouldn't go below 250mA.

post #27 of 58
Thread Starter 
Quote:
Originally Posted by Avro_Arrow View Post

500mA should do nicely.

Higher is OK too.

I wouldn't go below 250mA.



Ok good, I thought it was around that. One more quick question about power:

 

The TLE2426 says the power supply range is from 4V to 40V. Obviously I'm not going to have a 40V power supply, but I was thinking around 18V. The BUF634 says the supply voltage range is +/-2.25V to +/-18V. Its getting the voltage after the TLE2426 splits it, right? So if I had an 18V power supply, the BUF634 would be supplied +/- 9V? I want to make sure because if I get an 18V power supply, it will put out more than that when not under load, if I understand correctly.

post #28 of 58

Not quite...

 

The TLE, the BUF634 and the Op Amps all see the rail voltage.

The TLE and BUF634 generate the center voltage from the rail voltage.

In your case, the rail voltages will be 0 volts and 18 volts.

As you mentioned, the center voltage will be 9 volts.

 

With an 18 volt wall wort you should be pretty safe.

As you mentioned, the TLE is good to 40 volts.

The BUF634 is good to 36 volts

Most op amps are good to 32 volts but check

the data sheets to be sure.

post #29 of 58
Thread Starter 

I thought that the center voltage was 0V, then the rails were +9V and -9V? But it's +18V, 0V (ground), and -9V?

post #30 of 58

Nope. It's all relative.

 

Maybe this will help...

There are two wires coming from the wall wort.

One of the wires we think of as positive and say

the it has +18 volts (for example). The other wire

we think of as negative and say it has 0 volts.

If you use a rail splitter on these wires you will have

the 0 volts and +18 volts you started with and now you

will also have the +9 volts from the rail splitter.

The +9 volts is the half way point between the rails.

Now, in relative terms, if we make the +9 volts our ground,

the negative rail is 9 volts lower than ground (-9) and the

positive rail is 9 volts higher than ground (+9).

You have to grasp the concept that voltages are always

relative to what you are calling ground.

New Posts  All Forums:Forum Nav:
  Return Home
Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › Cigar box Apheared 47