Question on certain CAP symbols

[motterpaul]

Lately I have been seeing layouts where there are red panasonic type caps represented (for the nF value caps) but in the same layout you see smaller caps in yellow but they are also "nF-value" caps.

example:



BTW: Looking at the schematic I can see the 22n value is correct - but does the change of symbol mean anything else - like "use a ceramic" - or was that symbol used just because it was a matter of width - only two holes?

Now, here is the opposite:  A layout where there are small red caps where some are the expected nF value, but some are pF value, even though there are other caps of N-value that look different. Example:



So - should we always assume the given values are correct and ignore the look of the symbol?

[Beaker]

"So - should we always assume the given values are correct and ignore the look of the symbol?"

Yes. The cap "symbol used is arbitrary,  just used to represent a cap - any cap - of the stated value. What type of cap you use is completely up to you.

Even the smaller value electrolytic caps can be replaced with non-polarised multilayer ceramics in nearly all cases.

The few times you need to use a specific type of cap (invariably a tantalum), it will be clearly stated in the build notes.

[IvIark]

I tend to use the Panasonic graphic for anything 1n to 1u and ceramic for anything lower than 1n.  But in the past I have used the ceramic symbol for 2.5mm pitch nF caps simply because I have a lot of the multilayer ceramics up to 10u and so in some instances I personally would use them ahead of poly caps for the single hole pitch, or sometimes when space is at a premium.

But as Beaker said, it's just a cap.  I have tended to use graphics that represent what I would use but anything will work anywhere so the value is the important thing.

[motterpaul]

Thanks guys - so I'll assume that if I see a little yellow 22n that it is a ceramic 223

[nocentelli]

If I saw a tiny cap marked 22u I might be suspicious, but otherwise most layouts here at tagboardfx seem to be quite thoroughly vetted and scrutinised, and errant values are usually very quickly rectified.

[Beaker]

"so I'll assume that if I see a little yellow 22n that it is a ceramic 223"

You can use any type of 22nF cap you either want to use, or have in stock. It does not have to be ceramic.

What Mark is saying is that on his layouts, he tries to use the symbol most appropriate for the Farad rating of the cap, and of the physical size and number of rows spanned by the cap.

In other words, if the rating is pico Farads, and the span is only one row, he usually uses the yellow lozenge symbol for a ceramic disc cap, as they are the most commonly used caps with that leg spacing, and value range.

If the rating is nano Farads, and the spacing is three rows, he uses the rectangular poly box cap symbol, as it matches their leg span and usual value range.

Etc. etc...

[motterpaul]

Just FYI:

I found a layout with a real to life error in it yesterday (first one I have found, actually) - and it is a very old layout:

There is no designation for what D5 should be. I figured 5817 (as usual for power protection diodes), but guess what, this build is not working for me right now, and that diode there was the last thing I tried and I thought it would fix it. but it didn't.

Anyway - I am not getting any LEDs lighting up.

[Beaker]

They won't light up - or if they do it will be just barely visible. There are quite a few builds with LEDs for clipping, and I've built a few of them. None of them light up I'm afraid, it would be kind of cool if they did.

BTW, I've built this layout, and it works.

[Silver Blues]

Generally a diode in series with the power supply is for polarity protection and the called-for part, if not specified, is a 1N5817/5818 (preferentially) or a 1N400x (usually 4001).

[Travis]

They only light up when you play and you're getting clipping. As it clips that energy is turned into light. Fun stuff. Open up the pedal and look at the LEDs as you engage in glorious power riffing.

[motterpaul]

I did get the (Mad Professor) Honey Bear working, but the LEDs don't light up on that one, but I have made other pedals (crunch box, Suhr Riot & others) where the LEDS do light up. With Crunch Box they go full on and stay lit when the gain is cranked - and it sounds super creamy. I love the sound of LEDs - for some reason they have a smoother sound than any other diode.

I don't know what went wrong on the one above, I'll have to check it again later.  I am flying to England on Wednesday, but will only be there three nights (going to Southampton courtesy of Royal Caribbean). Sorry I will miss you Beaker  but I will have a pint for you.

[Beaker]

Yeah, I was in a hurry and did not give a very clear answer.

What I meant to say was that they won't light up like an indicator LED, but they will light up brighter as you increase the gain, and as you hit the guitar harder. Ultimately this is what I was trying to say to Paul - don't rely on the LEDs lighting up as an indicator of whether the pedal is working.

I know I had to ask the same question the first time I built a circuit with LEDs for clippers, as it seemed to work fine, but one set of LEDs were only flashing when I hit the strings and the other set barely lit up at all. It turned out this was normal for the circuit (Frantone Cream Puff). It does look much more interesting in the dark though!

I naively was expecting all the LEDs to light up brightly as soon as I plugged in.

I also know some circuit designs will give out much more light than others.