Help with buying parts- several questions

[Ponchus]

Hi all,
Before I hit this submit button on my order with Mouser, I'd like confirmation that I'm not completely on the wrong track...I'm confused about which caps to buy for this 808 clone...I've read the FAQ, and I still have some questions.

The FAQ states: "In a nutshell, you should use electrolytic when the capacitor is polarized. You can also use tantalum capacitors instead of electrolytic, but these are not commonly used. For any others, the basic consensus is to use film caps if they fit, otherwise use a mixture of film and ceramic capacitors."

Well, what if the cap should be polarized, but is of a smaller value than is available for electrolytics? For example, I need a 51pF cap. It doesn't say "non-polarized", so I'm assuming it's polarized. Yet electrolytics don't seem to come in this size. So I picked a ceramic instead. Is this ok?

Here is list of the capacitors that I need for this project, followed by the type I chose (ceramic vs. electrolytic vs. tant)...can someone please look this over for me? Thanks in advance.

51pF- ceramic
.047uF- ceramic
.02uF- ceramic
.1uF- ceramic
.22uF 35 volt tantalum- tantalum
1uF 50volt non-polar- electrolytic non-polar
10uF- electrolytic
47uF- electrolytic
100uF- electrolytic

Another couple of questions.
1.  For electrolytics, Mouser has various subsections, such as "General purpose", "High Frequency", "Low Leakage", etc. Does it matter which type I choose?
2.  I'm building an 808 clone...what size/color LED should I get, or does it not matter?
3. On Mouser, I can't seem to find pots that are a 1/4 watt in value, but I do see some that are .2W in value. Is this close enough?

Again, thanks for all your help

[niftydog]

Caps as small as 15pF are always non-polarised and ceramic caps are just about your only option when you're talking such a tiny value, so you're on the right track there. Not that in "good" schematics that there's a graphical distinction between polarised and non-polarised caps. Non polar caps consistor of two parallel straight lines, whilst polar caps have one straight line and one curved line.

1. for most uses, general purpose caps are fine. Low leakage caps (or low ESR) are usefull in switch mode power supplys. High frequency caps are just that, but high means REALLY high, like way above audible range, so not useful in our circuits.

2. pick the colour you like pretty much - most LEDs are 5mm.

3. Yes, there's only 0.05W in it, and chances are you won't be running them close to their limits anyway.

[formerMember1]

*EDIT*i was posting, but then niftydog posted, I didn't want to delete all my typing so here goes anyway,.. 

Metal film caps are usually what everyone wants for a good tone.  Or poly film, mylar, etc...  Ceramic caps i try to avoide becuase they tend to sound gritty and grainy, others may disagree, but the majority use metal film.  I have a tubescreamer i bought, and a popular mod is to change out the NP(non-polar) electros with metal film, and change the 2 tantalum for metal film.  I like the avx boxed metal film caps, but could only replace one tantalum, since the other tantalum was too close to the opamp.

BUT, like Arons says, some of the best sounding pedals used ceramic caps. 

I try to use metal film where possible, and if i need a small value in the pf range i usually go for silver mica.  I like silver mica.  Tantalum caps are smaller than other caps, and have said to last longer than electros that dry up after some years, others say the opposite,  I don't like tantalum.

My best suggestion would be to get both tantalum and NP electro and also get their values in metal film.  Some people like the electros and tantalum in their tubescreamer for a "drier" tone, others like the metal film.  You have to decide with your ears.

Try searching the forum, there is alot of info about building tubescreamers, and also if you already know what a tubescreamer sounds like, then you might want to read the forum for some mods, that way you could get the few parts for modding.  And if you don't end up modding it, you will almost definitely end up using the parts in another pedal.
Build it stock first though,...

The LED is usually 5mm, some use 3mm,  The cheap black plastic LED clip holder is better than a chrome bezel,  Get a LED with high milicandelas, ex. super brite LED.
you will save on battery power, also get the water clear, then sand it down with fine sandpaper(400-600 grit) and that will make it viewable from almost every direction.

Some people like Red LEDS, others like Blue or green,  I like RED,

Red will probably use the least power of battery.  But, you change the brightness of an LED, with series resistor anyway.

Definitely read GEOFX.com about tech of tubescreamer, that has everything you need to know about tubscreamers.  Geofx also has everything you need know about pedals,... well,... maybe not everything, since then no one would be on this forum. 

good luck,....