ROG Tri-Vibe 1uf Cap - polar/non-polar

[ttist25]

Hey there! 

Work is progressing slowly but surely on my TriVibe build.  I thought I was going to have all the board populated last night (actually 2am this morning) and then BAM - I realized I didn't have a 1uf cap.   

Anyway - after a trip to the only remaining Radio Shack in my area and a raid of what's left of the parts bin - I returned with a bounty of a 1uf polar tantalum and a 250v 1uf metal film cap. 

I'm not sure, but after reading some posts, I think either of these might work in this circuit but I wanted to get opinions.

Here are some pics that might help:
This is the original ROG schematic and the polarized 1uf cap in question
 

Here is a shot of the perfboard components from the ROG site


Here is the Andre Schapp PCB layout I'm using (note no polarity specified)


So - the question is - can I use the non-polar metal film cap here or should I try the little yellow 1uf polarized tantalum? 

Oh - here's a pic of the progress thus far:


Thanks again for all of your help!

[blackieNYC]

Either is fine. Polarized as shown (or back to back pair)
Or the metal film.
You can also use something bigger 2.2, 4.7, even a 10uf. I don't think there is a great concern with filtering out low frequencies at the end of that circuit. Just do it.

[Plexi]

I'm with blackie. As I can see, it isn't critical

[duck_arse]

the non-polar plastic film caps mean you don't need to think, just throw it in either way. they can replace polarised/electro/tantalum nearly anywhere that they'll fit (size and voltage). for a polarised cap you don't need to think either, because that resistor to ground makes the (-) end obvious. and a tantalum ALWAYS needs to be the right way round.

[ttist25]

Thanks for the responses. 

I stuck a 2.2uf non-polar cap in there as the 1uf I got was kind of big and clunky and I'm trying to make this build as neat as I can. 

I suspected that changing the value of that cap might only affect the tone but I wasn't sure.  It's in a position similar to some of the distortion/fuzz pedals I've had on the bread board but I'm still a noob (this is by far the most complicated circuit I've attempted) so I figured I'd better ask!

In reference to polar vs. non-polar - is it just in this specific application that it doesn't matter or can any polar cap be replaced with a non-polar equivalent?  Is there a rule of thumb about that?

Thanks again! 

PS - I grabbed my SPDT 3 lug switch and got ready to get busy and realized - crap - I need an on|off|on version.    I guess it'll give me time to double-check the board while I'm waiting for delivery! 

[bluebunny]

In reference to polar vs. non-polar - is it just in this specific application that it doesn't matter or can any polar cap be replaced with a non-polar equivalent?  Is there a rule of thumb about that?

It never really "matters" - capacitance is capacitance.  But you'll find yourself constrained by what's physically viable and what's available.  You find typical film caps up to 1uF.  Above that, they start getting infeasibly large and relatively rare.  So this if the start of electrolytic territory (which you won't find much below 1uF).

[blackieNYC]

Bipolar caps can be used in place of polarized electrolytics anywhere, but they are generally much larger and more expensive. In most applications they would be of no significant benefit.

[Plexi]

I use electrolytic everytime I can.
Bipolar, as another users mentioned, are expensive and dont make the difference.
I add that they're mostly in big sizes/voltages.

Sorry the offtopic.
I'm waiting the Ic's to start this one: is there an "speed ramp" mod?
Google didn't help me.

[Kipper4]

Speed ramp mod?
In what respect Plexi?
You want it to go faster or slower depending on picking? What?

[amptramp]

You could use either electrolytic or film capacitors but you should note that the lead with the line on some tantalum caps is the positive, not the negative like on aluminum electrolytics.  The left side of the cap is always more positive than the right side (at the output), so there is no need for a bipolar electrolytic.

[duck_arse]

the speed ramp mod - if you mean the sawtooth-er mod with oppsing diodes on an on/off/on switch, I think "yes". across the "rate" pot, it will also double (about) your lowest speed.

[Kipper4]

Oh that one. Thanks Stephen

[Plexi]

Duck and Kipper: thanks!!! 

ASAP I built it, I'll try.

[ttist25]

That makes perfect sense.  Thanks for the great explanations!