So when inserting them you aim the longer lead for the square pin, or the pin with the plus mark next to it. (there may be some with both markings, but I'm talking about where there is only one or the other)Īnd most aluminum caps come with the positive lead longer than the negative. for the LEDs I assumed the square was the anode (+) and the circle was the cathode (-). But I'll bet you've seen them with only a plus sign. This is a PCB to build a Fart Box, Usually only sold on tour. Have you ever seen only a minus sign on them? Probably not. Think about the silkscreen markings you've seen for electrolytics on boards. 1, The power supply direction is different: for the common anode LED display, the current flows from the PCB board to the led lights, and the RGB led light is uniformly powered, which. While the cap itself marks the minus side, the pc board usually marks the positive side. I can imagine some people these days using them the other way without knowing the history. They have been used for the plus pin on electrolytics for as far back as I can remember. So myself I use square for negative on electrolytics.Īt least it alerts you to the fact that there is a polarised component at that location. It makes more sense to me, because the minus is usually indicated by the bold stripe and is the main component identifier. With electrolytic caps I see a lot of designs where the square pin is the negative pin. You can also use a multimeter to check continuity (when the circuit is off of course) between the pins and a known ground.Ĭommathe wrote:Square pads often indicate pin 1 or the positive side of a diode/cap whatever. However, most Eurorack modules I've seen (DIY or otherwise) do not use topside ground fill.īy the way, does anyone know why people are not adding ground planes or topside fills in their layouts? This is the 21st century! It shouldn't cost any more and it is only hurting you to get rid of it in most instances. One clue to finding ground on a PCB is looking at the topside layer and seeing if any of the pins connect to the topside ground fill on the PCB. This doesn't tell you anything about ground or power unless you look at the package pinout on the part datasheet. Lots (but not all) of through-hole component libraries (especially what I've seen in Eagle) use a square for the through hole outline of pin 1 of the IC and use a circle for everything else. I mostly work in SMT, but I think you are talking about PCB footprints for Through-Hole components (PTH). Do you have a board and you are trying to figure out if a pin is connected to ground? Make sure the anode(the long leg) goes in the round solder pad and the cathode(the short leg)goes in the square solder pad. I'm not 100% sure what you are asking here.
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