Question about schematics nomenclature (pic inside)

[omnedon]

Ok. I'm totally self taught, so I learn as I go. Now, I'm trying to learn and understand schematic nomenclature. If anyone has a link to a glossary or a tutorial on schematic symbols and conventions and the like, it would sure be appreciated.

For now, I have specific questions about this schematic in particular:

http://www.a1k0n.net/projects/coleco/video_sch.png

It's a video amp board (composite) for a ColecoVision.

Now, I understand the triangle is the IC, and I can spot the resistor symbols, and the capacitor symbols. My question is about the crossing lines. An example is pin 4 from the IC, which leads to the negative terminal of the C2 capacitor, and pin 2, which seems to lead to the negative end of the C1 27pf capacitor. The wire from pin 4, and the wire from pin 2 seem to cross on their way to their destinations. Does that mean they literally connect at that junction on the schematic? Does the green colour mean they do not connect at that point in the diagram? :help:


Also, if I am making any mistaken assumptions on the meanings so far, please correct me. I'm here to ask about schematics conventions, not to stroke my ego. :glee:

Thanks for any help shared!

[davidleeroth]

The green blob means there's a connection otherwise they just overlap. For example there's no connection between pin 2 and 4 on the chip.

[SkiDragon]

The green blob means there's a connection otherwise they just overlap. For example there's no connection between pin 2 and 4 on the chip.

I second that.

[ClubNinja]

The green blob means there's a connection otherwise they just overlap. For example there's no connection between pin 2 and 4 on the chip.

That's right. When wires connect, a large dot is placed there indicating a "node". When they cross, no node is drawn. So, only make wire connections at the node dots or between components (obviously).

[omnedon]

Thanks all! Now I'm not assuming anything. Assuming and circuits don't mix. LOL

[FABombjoy]

Assuming and circuits don't mix.

Sure they do... they just create fire.

[leonk]

One other thing you have keep in mind is the "-" or ground in the diagram. To make them readable, they are all separate, but in real life, they should all be connected.

You should never EVER have seperate grounds in any circuit.

[rbudrick]

Yeah, that is all correct. When you look at very complex diagrams, you'll see it is extremely difficult, if not impossible to not cross drawn lines. It's is a mega-space saver too to do so.

-ROb

[omnedon]

Funny thing is, after the help in this thread, it's like an epiphany. I can READ!

Quick question about capacitor symbols. Which end of that symbol is the negative post on the cap?

[Mr-E_MaN]

The curved end is negative. I wanted to make sure, so I done a little search on the net, and came up with this:


On schematic diagrams the flat side of the capacitor symbol is the positive (+) side and the curved side is the negative (-) side. The positive end must be kept at the higher electrical potential (more positive voltage). Modern film capacitors are non-polar, so you don't have to worry about polarity when replacing old paper caps with new film capacitors.