What is the orientation of these caps?

[steveyraff]

Hey guys,

The 1u caps on this are non electrolytic. Unfortunately the only 1U caps I have are electrolytic.

Can I use them in this build and if so, what way around should I put them in?

Many thanks!

[GibsonGM]

Th "+" goes up, toward the 9V that's coming in.  If I'm not mistaken, you can just make out a gray band at the bottom of them telling you this, altho it's not that clear....that would be the "-" band.     Just make sure the + is going toward the point of higher potential, you can measure this with a DMM after the fact if you're not sure.


See why a schematic is so useful?      Sorry, had to toss that in there. 

[steveyraff]

Th "+" goes up, toward the 9V that's coming in.  If I'm not mistaken, you can just make out a gray band at the bottom of them telling you this, altho it's not that clear....that would be the "-" band.     Just make sure the + is going toward the point of higher potential, you can measure this with a DMM after the fact if you're not sure.


See why a schematic is so useful?      Sorry, had to toss that in there.  

Are you sure you are talking about the 1u caps and not the 100u caps? I can't see any grey band on the 1u' s.

Yep, a schem would be nice lol

[induction]

The answer is on the schematic (and way too much trouble to figure out from the vero).



It's easy to see which side of the cap has higher voltage, but in this case, the cathode is marked with a '+'. On the layout, the cathode goes toward the top in both cases.

[Ice-9]

The 1uf caps I can see are C10, C11 and the marking in the schematic are shown correct so just put them in that way. 

[GibsonGM]

Top 1u cap, C10...where it goes out to Gain2, that is the negative.
C11, the leg going to "fuzz vol 3" is the negative.
In both cases, the lower leg is negative.

Electrolytics can be kinda negative in the signal path, many say - see what yours sound like. It's a personal preference.  If so, even a .68u poly cap  might make a difference for you.  Some ppl. don't care either way - an electro on an output never bothers me...

Sorry, I had just woken up when I replied, and mis-read your request about 1u as the 100u's on the vero  

Induction: good eye, but there's no 'cathode' on a capacitor. Just a positive and negative plate...

[induction]

 

[PRR]

> no 'cathode' on a capacitor

For *electrolytics*, cathode and anode are respectable names for the two electrodes. Not un-common in the 1920s.

However "nobody" calls them that in recent decades.

[steveyraff]

Thanks guys, I worked it out from the very kindly displayed Schematic - which I failed to find on my own accord.

Being a noob and everything, it was actually a great exercise for me to work orientation out from a schematic. I will definitely remember to do this myself should this happen again in the future.

As always, many thanks again for your patience and help - highly appreciate it!

[GibsonGM]

Ha, who woulda thunk it?  Sorry, Induction! You revived a long-lost name for the plates, good deal!  
Psst: Isn't the anode the one marked "+"?  I do that all the time myself.

>>>  Glad to hear it, Steve!

[PRR]

[GibsonGM]

2a and 2b seem to be at odds with each other, even tho we can see they're actually not. 

I identified the "+" terminal of the electrolytic as "anode", analagous to the plate of a tube or anode of a diode...current flowing out of this terminal to a device, the classic scenario.

2b almost uses a different convention...if we use the same rationale, we could say the cathode of a tube emits to the plate, and therefor is an anode!

I'm glad we generally only use the terms as they relate to diodes & tubes now   Maybe this is why their usage went away?

[PRR]

> seem to be at odds

Difference is "delivering" current or "accepting" current.

Energy flows OUT of sources and INTO loads.

[anotherjim]

Same thing could be seen on silk screen pcb ID for diodes or LED's - a diode symbol (optional) with a + marked by the cathode (not the anode). Presumably it stemmed from diodes as power supply rectifiers (vice battery), but was used for any type of diode whatever it's circuit function. Many repairs failed when the tech took it for granted that a + meant anode 

[GibsonGM]

Gotcha, Paul!

I always take a "+" on a schematic or PCB to mean "most positive point" for the device in question (like a cap).  Haven't come across that issue with LEDs or diodes, Jim....seems kind of odd.    Do you see this on new stuff, as well?   

[anotherjim]

I haven't seen + cathode marking since kit made in the '80's, and it may have been a Brit/Euro thing. That said, the last time I saw it was on a board in a Westinghouse product.

[GibsonGM]

If you were to take a voltage measurement across the (dead) component, would you find the part to be reverse biased, or forward?  I mostly end up doing that, and it makes sense if you can see your polarity...not 100% on what you'd see on the reading from the description.   In the past, if I see a diode symbol, I've gone with the way the diode pic is oriented....

[anotherjim]

Well, having been bitten by it, I would always take a note of the parts physical direction and applied voltage.
It could be meant to be reverse.
..or could have been fitted reverse in error.
The part could have vaporized taking most of the print with it, leaving just the "+" visible.
The diode symbol wasn't always printed, just the "Dn" with a "+" at the cathode end, and some breeds had every kind of diode ID'd with a D prefix.

Hopefully, just a diode symbol is used nowadays, since so long as it's correctly printed, you can't go wrong.

Another variation with silk-screen for LED's was a circle with a flat on one side (the physical cathode) but still a "+" by that flat. Confusing when the printing isn't well executed or obscured. Now we sometimes see just the flat sided circle used, which is sensible, but also sometimes with a "+" on the anode side!

[PRR]

> take a voltage measurement across the (dead) component, would you find the part to be reverse biased, or forward?

In this case the project is part-built (not dead).

Yes, you can build 99% of projects with-out the e-caps, use meter to find the more-positive of the two holes where each e-cap will go, and install them that way.


> LED's ... but still a "+" by that flat. Confusing ....but also sometimes with a "+" on the anode side!

This is an old-old problem. Comes from rectifier diodes. See nearby discussion on Anode vs Cathode. The definition changes depending if the device delivers power or accepts power. But a rectifier diode accepts power from PT and delivers power to the rest of the circuit. On the workbench, we "see" the rectifier as our "power source", even though it does not actually make power. What we really want to know is which side will give us which polarity. The "+" mark on the rectifer goes to the "+" mark on our power-supply capacitor. However if we use a diode further down the chain, to give forward current we connect power + to diode anode, logical. + to -. There is much potential for confusion. Most rectifiers dropped the "+" mark (bridge assemblies a major exception).

For LEDs you can almost always tack-in, smoke-test, and then reverse any which show large voltage drop with no light output. Within wide limits, if the LED is happy forward in circuit, it will be dark but un-damaged if installed backward.

[antonis]

There is much potential for confusion.

Same as with an A-meter...

It seems odd to connect in series something with "reverse" polarity as all series elements in a circuit are connected with a (+) to (-) order...