A Newbie Question About Capasitors

[Opencan]

I want to make my own Pre Amp and Distortion by a schematic identical to an MXR MicroAmp and a MXR Distortion plus.

In the schematics 2 kinds of capasitors shows, one with 2 prallel lines, and one with a line and half a dent line, and a "+" sign on what side.

here is the picture of a schematic for what I intend building with the 2 different capasitors bolded:

http://members.lycos.co.uk/driftingfuzzbal...tion%20plus.jpg

I've done the board (made my own from a jewl box of a CD ) and almost everything is totally planned, and in a few hours i'll go to shop for the parts I need, so can you please tell me what I should ask for at the shop?

Plus, there are 3 potentionmeters I need, one is a linear potentionmeter, one is a reverse log. and one is a log. potentionmeter.

what log. stands for? o.O

And for last, is there anything that I should get a certain brand over another in thoes components on the schematic I added? (I already got a certain diodes and ICs type)

Thanks alot, Ron

COOKIE PRIZE FOR THE RIGHT ANSWERS!

(shipping is not included, offer valid only on orders over $150 in Israel, Only physical addresses and rural boxes are accepted. Post office box's and APO's Do Not Apply, valid only on non-oversized items, I reserve the right to end or change this Free Cookie Prize offer at any time)

[TeiscosRock]

The capacitors with 2 parallel lines are normal Film or Ceramic caps, non-polarized. The ones with the positive (+) sign are electrolytic (polarized) with the positive lead facign in the direction of the (+) sign.

I dont remember that particular schematic needing 3 different types of pots.. and I'm only seeign two on the schem... You should be fine with just a Linear and a reverse Log (if you have somewhere that it NEEDS a reverse log, according to the schem you could use linear taper pots for both of them.)

Log stands for... Log. xD I really am not clear what it means.

Theres no certain brand of anything you need, a cap is a cap and a resitor is a resistor. Just make sure you have the right IC. Having the wrong IC isnt good! (There are some really trciky schems that require certain brands of IC)

[Mr Alex]

mmmk forget the cookie, customs will eat it,

the crazy one with the plus sign is polarised(+ and-) and the other is non-polarised, log means logrithmic, and I doubt you'll find a reverse log, just swap ends of the taper for reverse. I built a superior version to what you're wanting(superior in the sense that it was a od250(same thing kinda) and it was modified for better tone. Swapping the terminals for the reverse log pot does work.

edit: dang beat me to it. and he needs the 3rd pot for the micro amp.

Edited September 1, 2005 by Mr Alex

[MerlinTheWizard]

The polarized, output capacitor is marked as a tantalum one. That's not pretty. Tantalum caps may seem "fancy", but they are no good in audio signal paths. Don't use them. (That's the short version. The long version is a long analysis of the tantalum caps behavior over the whole spectrum, with detailed measurements...)

Just use a regular electrolytic cap. Actually, since it's 1 µF, I wouldn't even bother with a polarized cap here. I would use a plastic, non-polarized, 1 µF capacitor instead. That will sound better.

Then again, I would never use a 741 as an opamp in any audio circuit either, so...

[Opencan]

The capacitors with 2 parallel lines are normal Film or Ceramic caps, non-polarized. The ones with the positive (+) sign are electrolytic (polarized) with the positive lead facign in the direction of the (+) sign.

I dont remember that particular schematic needing 3 different types of pots.. and I'm only seeign two on the schem... You should be fine with just a Linear and a reverse Log (if you have somewhere that it NEEDS a reverse log, according to the schem you could use linear taper pots for both of them.)

Log stands for... Log. xD I really am not clear what it means.

Theres no certain brand of anything you need, a cap is a cap and a resitor is a resistor. Just make sure you have the right IC. Having the wrong IC isnt good! (There are some really trciky schems that require certain brands of IC)

←

YOU WON A COOKIE

to claim your prize private message me for a phone number in Israel with a call price that is sky-high and wait until someone answers you call and tell you we are out of them

I should just turn the pot. around so the edges will be turned? I have no clue what "reverse" actually does..

mmmk forget the cookie, customs will eat it,

the crazy one with the plus sign is polarised(+ and-) and the other is non-polarised, log means logrithmic, and I doubt you'll find a reverse log, just swap ends of the taper for reverse. I built a superior version to what you're wanting(superior in the sense that it was a od250(same thing kinda) and it was modified for better tone. Swapping the terminals for the reverse log pot does work.

edit: dang beat me to it. and he needs the 3rd pot for the micro amp.

←

I wish I actually listened while making my electronic degree... 3 years of sleeping.. yet got pretty good grades though

Actually, my problem is way too simple, I have NO TOOLS. marked a CD jewl box and made holes using a heated up pin. will make the circuit using hot glue and cables...

The polarized, output capacitor is marked as a tantalum one. That's not pretty. Tantalum caps may seem "fancy", but they are no good in audio signal paths. Don't use them. (That's the short version. The long version is a long analysis of the tantalum caps behavior over the whole spectrum, with detailed measurements...)

Just use a regular electrolytic cap. Actually, since it's 1 µF, I wouldn't even bother with a polarized cap here. I would use a plastic, non-polarized, 1 µF capacitor instead. That will sound better.

Then again, I would never use a 741 as an opamp in any audio circuit either, so...

 

←

So, you say I should just use the cheap caps?

Anything you will recommand me to use at the same price range and ease of circuiting?

Anyhow, here is the schemes I'm actually using:

http://members.lycos.co.uk/driftingfuzzbal...tortionplus.pdf

http://members.lycos.co.uk/driftingfuzzbal...ampdistplus.pdf

And here is what I did with the jewl box. will need some more work of course:

http://members.lycos.co.uk/driftingfuzzbal...P_061608_01.jpg

http://members.lycos.co.uk/driftingfuzzbal...P_061636_01.jpg

http://members.lycos.co.uk/driftingfuzzbal...P_062028_01.jpg

I bet this is the lowest budget project here since.. ever! (and I'm starting to think of second-hand resistors already ~_~)

Edited September 1, 2005 by Opencan

[lovekraft]

So, you say I should just use the cheap caps?

No, what Merlin said was to use a non-polarized cap - preferably a poly film cap, but a ceramic will do (after all, it's a distortion box). Polarized caps of any kind really have no business in the signal path, and even if you could live with the audio degradation, they have a nasty habit of failing with litlle or no warning, for very stupid reasons. I really don't like seeing electrolytics outside power supplies and bias circuits, and I have no use for tants whatsoever (Boss, MXR, et al, use tantalums simply because they're cheap and small).

Then again, I would never use a 741 as an opamp in any audio circuit either, so...

I totally agree - regardless of any old-school mojo, the noise level alone is enough to drive me crazy!

[Mr Alex]

AWW come on guys, the hum and hiss is the best part, not to mention the fact that if you touch it(DON'T!) it picks up EVERY radio frequency(within reason) at once. Although that may be to do with the fact that I live near my cities main transmission tower.

You gotta have faith in the old skool. PLUS, it "Goes Faster".

[Opencan]

So, you say I should just use the cheap caps?

No, what Merlin said was to use a non-polarized cap - preferably a poly film cap, but a ceramic will do (after all, it's a distortion box). Polarized caps of any kind really have no business in the signal path, and even if you could live with the audio degradation, they have a nasty habit of failing with litlle or no warning, for very stupid reasons. I really don't like seeing electrolytics outside power supplies and bias circuits, and I have no use for tants whatsoever (Boss, MXR, et al, use tantalums simply because they're cheap and small).

Then again, I would never use a 741 as an opamp in any audio circuit either, so...

I totally agree - regardless of any old-school mojo, the noise level alone is enough to drive me crazy!

←

So I should get something like that:

http://img.ebigchina.com/cdimg/331133/1277.../1112605848.jpg

or that:

http://www.elwire.com/faq/seq/seq5/images/0.1uF.jpg

right?

And what SHOULD I use instead?

AWW come on guys, the hum and hiss is the best part, not to mention the fact that if you touch it(DON'T!) it picks up EVERY radio frequency(within reason) at once. Although that may be to do with the fact that I live near my cities main transmission tower.

You gotta have faith in the old skool. PLUS, it "Goes Faster".

←

o.O

What are you talking about?

[MerlinTheWizard]

Yep, I'd say use polyester caps, and replace the 741 with some good but not overly expensive opamp, like the OPA134. A world of difference.

As for this distortion circuit, I personnally think it's a bit crude. You get "smoother" distortion with diodes in the feedback loop of the opamp (like in some solid-state, "blues-typed" units, the Boss OD, for instance, I believe). But after all, your ears will be the judges; so try this unit first (that will be a good start), and then you can try a little more sophisticated designs...

[Opencan]

Yep, I'd say use polyester caps, and replace the 741 with some good but not overly expensive opamp, like the OPA134. A world of difference.

As for this distortion circuit, I personnally think it's a bit crude. You get "smoother" distortion with diodes in the feedback loop of the opamp (like in some solid-state, "blues-typed" units, the Boss OD, for instance, I believe). But after all, your ears will be the judges; so try this unit first (that will be a good start), and then you can try a little more sophisticated designs...

←

Is there a difference in the costs of thoes caps?

Thanks for the tip, I'll get an extra IC of OPA134 and try it as well on the same circuit, but is the wiring the same?

can you add this diode to the circuit and send me the schem.s (and the diode brand) so I'll be able to understand better? I know all the term only in Hebrew :\

I don't mind picking some extra stuff for moderation, I just know nothing about it :\

Is there anything I can learn from (in English) about building circuits and the basics about differences about parts and stuff like that? (I do know how a wave acts, to calculate thoes stuff, the harmonics thing, how to actually fix stuff in circuits and all that, I just need a guide)

And I really don't have any problem doing way more sophosticated designs, I don't find it problematic. The reason i go this simple is: 1. keeping the costs as low as possible, even if we talk about the plate i'll have to buy for circuits with more stuff on them, because now I've just drilled a CD box

2. Trying out my skills, because in lab class we only did expirements like proving a resistor makes a capasitor discharge slower on DC and how a simple amplifier works, but nothing more than that

3. I don't have the right tools to find problems right now, so I can debug only simple circuits I fully understand

When iy will work I'll play a bit with it and go to harder things.

And the main reason I go THAT simple is that I want this unit to function as headphones amplifier, with distortion option, and thats why I don't really care that much about the quility comparing to stuff that will be used on big amps.

[MerlinTheWizard]

Is there a difference in the costs of thoes caps?

No, not really. Those are pretty cheap. They are just more suited to audio signals.

Thanks for the tip, I'll get an extra IC of OPA134 and try it as well on the same circuit, but is the wiring the same?

Yes, the pinout is the same. You can find the data sheet Here . Should not be any problem using it. Just pay attention to the package - they come as DIPs as well as SMDs. It probably makes sense to put the extra 10 pF capacitor that is noted in dashed lines, because the OPA134 is much faster than the 741 and more prone to high-frequency oscillation.

As for close alternatives to the schematics you posted, I meant something like this: Tube Reamer, which is actually more or less a clone of the famous Tube Screamer (Ibanez).

Edited September 1, 2005 by MerlinTheWizard

[Opencan]

Yes, the pinout is the same. You can find the data sheet Here . Should not be any problem using it. Just pay attention to the package - they come as DIPs as well as SMDs. It probably makes sense to put the extra 10 pF capacitor that is noted in dashed lines, because the OPA134 is much faster than the 741 and more prone to high-frequency oscillation.

As for close alternatives to the schematics you posted, I meant something like this: Tube Reamer, which is actually more or less a clone of the famous Tube Screamer (Ibanez).

←

I'll try each and every tip you said, after i'll complete the original circuit on a solderless breadboard. I'll see what I like the most, and copy it to the board

I was about to use that cap anyway

Thanks for everyone for their help (don't think you heard the last of me! i'm a pain in the butt when I'm not completely sure about things!)