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Schematic management
Hi Guys


When we draw a schematic by hand we are limited by the paper size as to how much circuitry we can comfortably fit onto the page. Symbols and text have to be large enough to read clearly, preferably without the need for a magnifying glass. Hand rendering usually invokes our sense of proportion and we try to keep similar symbols the same size as each other, and try to have room for what needs to be shown. We try to organise the circuit flow so it easy to follow and often use connection symbols such as GND and V+ to show things that are tied to each other without having to pull a line all the way across the page.

With computer software, and PCB design programs like Eagle, schematic entry is much the same as hand rendering except that we go to a library within the program to find symbols, then 'drop' them in place. Then we connect them with 'nets'. As we add more components we run out of space as far as the scale of our view goes, because Eagle defaults to a certain effective page size. We can zoom out and add more parts then use the 'fit' function to resize the circuit to the screen size. Things are smaller now, but likely with modern monitor sizes we can still read component names and values. However, it is very easy to get to a point where you have to begin zooming in to read text, and that becomes a problem if you ever want to print out the schematic.

In drafting, there are standard size "sheets", or paper sizes. 'A' is the same size as a North American letter size, 8.5" x 11". The orientation can be long-side vertical (portrait) or long-side horizontal (landscape). Size 'B' is twice the area; 'C' is four times; 'D' is eight times and 'E' is sixteen times. Obviously, for hobbyists and home users, printing anything other than 'A' size is impossible  Yes, there is 'legal' size paper and in Europe size A4 is slightly larger than letter size.

Eagle provides a facility to have multiple sheets for the schematic. This allows you to break the circuit into smaller portions that can be printed more easily and more legibly. When we need to make a connection tie from one sheet to another, we use "ports" or "wire links". These are DEVICES in the Eagle library that let you have these page breaks yet on the board the same-labelled ports are tied together by a trace.

Messages In This Thread
Schematic management - by K O'Connor - 08-06-2019, 07:50 PM
RE: Schematic management - by K O'Connor - 08-06-2019, 08:08 PM
RE: Schematic management - by K O'Connor - 08-06-2019, 08:20 PM
RE: Schematic management - by K O'Connor - 08-07-2019, 01:32 PM
RE: Schematic management - by K O'Connor - 08-07-2019, 01:49 PM
RE: Schematic management - by K O'Connor - 11-09-2022, 07:58 PM
RE: Schematic management - by K O'Connor - 11-21-2022, 01:39 PM

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