mk2 layout capacitor polarity questions?

[tacobender]

OK so I've done a few mk2 builds so far, but I've used bi-polar caps until now. So I'm wondering if anyone can explain why most of these layouts only have an orientation on some caps. Like the first. 01uf doesn't have an orientation, but the 5uf cap next on the board does. And I'm guessing the little tab under the 5uf is for the negative side(please correct me if I'm wrong) Thanks for any advice, Mike.

[chuckd666]

Higher value caps are generally polarized Electrolytic caps - they have the positive and negative ends. The minus sign denotes the negative end.

Smaller value capacitors are generally non-polarized and therefore do not require correct orientation.

There is some crossover- you will see 1uf up to 2.2uf caps that are non-polarized, and you will see 0.47uf caps that are polarized.



In this layout for the MKII Tonebender you will see the blue capacitors are higher values, and are polarized. The yellow capacitors are lower values and aren't polarized.

I don't know the specifics, but there would be technical reasons as to why certain capacitor designs lend themselves to certain value ranges. Someone smart could help you out I'm sure. 

[tacobender]

Thanks, that's pretty much the same layout I'm using, but mine is the 81D layout with some higher value caps and resistors in a few places. For the. 01uf caps I've got sprague pio's, not sure if they are bipolar or not they have no band, no plus or minus sign so I'm hoping they are. I guess I'll find out when I plug in. 9v isn't enough to blow one of these, right?

[chuckd666]

I doubt anything would blow up! I guess it depends on the component...

Sprague PIOs? Crikey. They're expensive. Probably too nice! Those caps are 99% likely to be non-polar.

[tacobender]

Thanks, I was hoping that was the case... wanted to go mojo with this one. Got carbon comps and the whole shabang, even got some old army germaniums I'm gona try out.

[Electric Warrior]

You know they used carbon film resistors and metallized polyester film caps back int he day? 

[tacobender]

Really? All the pics I'v e seen look like carbon comp's. Didn't know they had metal film back then. What do you use for your builds?

[tacobender]

Oh wait, those tropical fish caps are metalized polyester?

[Electric Warrior]

There are no "tropical fish caps" in MKIIs, but yes, they were usually metallized polyester capacitors - though I'm sure there must have been non metallized types as well.

The tan resistors are Iskra carbon film, the brown ones Piher. The red capacitors are Iskra KFMU, which was a metallized polyester type.



Earlier units had some Wima TFMs were metallized poly as well.
For a while they used styroflex capactiors for the 0.01/0.015µF caps.

[tacobender]

What's the difference in the sound? The Guy I got all my carbon comps from had a big bag of reddish collored resistors, I pased on them because I thought they were just old carbon film, maybe I shouldnt have!

[Electric Warrior]

No difference in sound in a 9v powered circuit, but carbon comps tend to drift a lot over the years.

[tacobender]

Are these the same resistors they put in the old Clyde McCoy wah's?