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instructables print turn your eagle schematic into a pcb generated by foxit pdf creator © foxit software http www.foxitsoftware.com for evaluation only página 1 de 19 instructables.com by westfw september 29 2006 turn your eagle schematic into a pcb in a previous instructable i provided an intro to schematic entry using cadsoft s eagle editor in this instructable we ll make a printed circuit board from that schematic i guess i should say that we ll make a pcb design making the physical board is a different task and there are a lot of tutorials on the net and even some instructables on making the board after you have the design cadsoft eagle generic information cadsoft eagle is available from http www.cadsoftusa.com cadsoft is a german company that is a veritable mecca of software distribution enlightenment in addition to the reasonably-priced professional pcb design packages 1200 they have freeware lite non-profit and other intermediate licenses their software runs under windows linux and macosx it s slightly quirky with a steep but not too high learning curve on the front end but from most reports it is not any more so than other professional cad packages they have online support forums that are active from both the company and other users the package is under current development and gets better with each release a number of pcb fabricators will accept their cad files directly it s good stuff use it propagate it buy it when you go pro i step 1 starting from the schematic so this is the schematic we have from the schematic instructable up in the file menu there s a switch to board selection if we do that from a bare schematic it will offer to create the board from the schematic for us say yes and then leave us sitting in the board editor http www.instructables.com/id/turn-your-eagle-schematic-into-a-pcb print 7/2/2008

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instructables print turn your eagle schematic into a pcb generated by foxit pdf creator © foxit software http www.foxitsoftware.com for evaluation only página 2 de 19 i step 2 menu commands used the board editor looks a lot like the schematic editor with some different commands here s a summary of the iconic commands that i use in this instructable and some brief sumaries info shows information about an object component signal trace etc move allows components to be moved same as schematic group groups a collection of objects into a group that can be manipulated simultaneously delete delete an object items created in schematics need to be deleted there smash separate the text labels of a part from the part itself so they can be moved independently break add a corner to a line or trace route turn an airwire into a trace line draw lines usually in non-copper layers route is for drawing copper via create a hole and pad associated with some signal actually we ll use a text command hole a hole that isn t associated with a signal ie for mounting ratsnest recomputes airwires and polygons eg after components have been moved change changes an object s properties ripup changes a routed trace back to an airwire sorta equivilent to delete for traces text add text polygon create a polygon actually we ll use a text command autoroute invoke the autorouter drc invoke the design rule check and parameter setting i ll descrive the remaining icons toward the end and assign them useful or useless step 3 the untouched pcb design this is what the newly created board design will look like all your components will be in a clump over to the left of the origin and there will be a frame that marks the allowed size of a board when using the freeware or lite versions of eagle 80x100mm all the component pads will have to be inside that outline when you move them around although you can cheat a bit and have traces or board outlines that exceed the board size limit this has the annoying side-effect that if you pick up a component from it s original localtion you can t put it back down outside the outline however you can use esc to abort the move and the component will revert to its original location ok a few defintions are in order http www.instructables.com/id/turn-your-eagle-schematic-into-a-pcb print 7/2/2008

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instructables print turn your eagle schematic into a pcb generated by foxit pdf creator © foxit software http www.foxitsoftware.com for evaluation only página 3 de 19 all the signals you created in the schematic are currently air wires thin yellow lines that are drawn in the shortest possible way crossing each other as needed they stay connected to component pins even when you move the component around the ratsnest command recomputes and redraws these after you move things around and say make two connected pins closer together than they used to be routing a signal consists of turning an airwire into an actual copper trace on some layers of the board and positioning that trace so that it doesn t short agains other traces on the same layer of the board the freeware version of eagle only supports a top and bottom layer and as hobbyists we have motivation to try to use only one layer a signal can transition from one layer to another using a via which is a conducting hole sorta like a jumper and we ll use jumpers to implement the top level of the board if we can make the board mostly single-sided creating the pcb design consists of placing all the components in logical places and routing all the airwires in a way that allows the design to work i step 4 about board layers the eagle board editor has many more layers than the schematic editor a confusing multitude of layers most of the drawing commands have a layer-selection pulldown menu that you can use for specifying which layer you want to draw on exceptions include objects like vias that span multiple layers here are some of the more important layers http www.instructables.com/id/turn-your-eagle-schematic-into-a-pcb print 7/2/2008

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instructables print turn your eagle schematic into a pcb generated by foxit pdf creator © foxit software http www.foxitsoftware.com for evaluation only página 4 de 19 i step 5 move the components into the legal area the first thing we want to do is move at least some components into the legal board area where we can work with them if you have a particularly large board with many components you might want to do this a section at a time for this sample board we have plenty of room and we can move them all at once using the group-move feature select the group icon then click and drag to make a rectangle that goes all the way around the components then select the move icon and right click right clicking selects the group instead of a single component and drag the set into the board outline use the zoom button to tighter the view http www.instructables.com/id/turn-your-eagle-schematic-into-a-pcb print 7/2/2008

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instructables print turn your eagle schematic into a pcb generated by foxit pdf creator © foxit software http www.foxitsoftware.com for evaluation only página 5 de 19 i step 6 shrink the boad outline a bit the full legal side of the board is bigger than we need shrink the outline by using the move tool click on the center of the top horizontal line which selects the whole line instead of an endpoint and move it down then click on the center of the rightmost vertical line and move it leftward clicking near the center of a line moves the whole line clicking near a vertice moves only the point it doesn t have to be perfect at this point we re mostly looking for a better view for the next steps oh yeah click the zoom button to re-zoom the window on the smaller outline http www.instructables.com/id/turn-your-eagle-schematic-into-a-pcb print 7/2/2008

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instructables print turn your eagle schematic into a pcb generated by foxit pdf creator © foxit software http www.foxitsoftware.com for evaluation only página 6 de 19 i step 7 start placing the components now we need to move the components to near where we want them on the final board or we want to move them to sensible places that will make the placement of traces easier a lot of the art of making pcbs and especially single sided boards lies in finding good places for the components in general you can start by placing the components similar to how they appear on the schematic this breaks down when a chip has multiple gates or the diagram in the schematic symbol has vastly different pinn placement than the actual chip but it s a good place to start for discreets and simple components the worst that will happen is that you ll have a layout that makes sense even if it doesn t route well in this case i put the power output transistotrs near lamps that they re associated with and i looked on the web for a 555 layout that would work well for the longest time i tried to do boards with the timing cap placed near the timing resistors and i always needed a jumper sigh let no one else s work evade your eyes http www.instructables.com/id/turn-your-eagle-schematic-into-a-pcb print 7/2/2008

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instructables print turn your eagle schematic into a pcb generated by foxit pdf creator © foxit software http www.foxitsoftware.com for evaluation only página 7 de 19 i step 8 check signals to see how they ll route one way to get hints on part placement is to look at some significant signals to see whether they have nice straight paths or whether they zigzag all over the board first use the ratsnest icon/command to have eagle recompute the airwires the way things are now i have nice straight connections from the transistors to the lamps but if i type show gnd in the command line i see that this is at the expense of making the ground signal zigzag so i swap the transistors because gnd is more important to have straight imho ymmv etc this ends up putting the transistors near the supplies that they switch rather than near the lamps that they switch to so that still makes sense from a circuit point of view too after the rest of the components are placed in ok-looking relative locations i can squeeze them together again manually moving them one at a time no magic command for this and shrink the board outline some more http www.instructables.com/id/turn-your-eagle-schematic-into-a-pcb print 7/2/2008

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instructables print turn your eagle schematic into a pcb generated by foxit pdf creator © foxit software http www.foxitsoftware.com for evaluation only página 8 de 19 i step 9 load design rules since we re hobbyists we want to make our board with wide traces and big spaces see http www.instructables.com/id/ezvighubgcep287bjb so we ll load up that set of hobbyist design rules before we start laying out tracks click the design rule check icon and use the load button to load hobby.dru from my other instructable or you can modify values manually and individually of course or leave them as is http www.instructables.com/id/turn-your-eagle-schematic-into-a-pcb print 7/2/2008

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instructables print turn your eagle schematic into a pcb generated by foxit pdf creator © foxit software http www.foxitsoftware.com for evaluation only página 9 de 19 i step 10 fix incorrect package you can see how the design rule change has already modified the board pads are bigger and they re all round you ll also notice that one of the resistors is set as a non-vertical package unlike the rest this was probably an error in the schematic entry and it didn t matter when all we had was the schematic now that we are making the board we want to change the package as appropriate when you select the change package tool and click on the part to change you ll be shown a list of all the legal packages for that part these should be the same ones that showed up in the schematic add dialog there are other ways to enter a change command in the text command entry area that you ll want to look into if you need to change a lot of devices to a particular package so you can skip going through the list for each one something like change package r-us/0207/2v and then just click on each component http www.instructables.com/id/turn-your-eagle-schematic-into-a-pcb print 7/2/2008

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instructables print turn your eagle schematic into a pcb generated by foxit pdf creator © foxit software http www.foxitsoftware.com for evaluation only página 10 de 19 i step 11 try the autorouter now we ll see if the autorouter can do some of the work for us the eagle autorouter isn t the best in the world but even when it does a bad job it will give us some general hints on how things need to look or where the trouble spots are clcik the autoroute icon and a dialog box will pop up the default parameters will produce a double sided board and we want to at least try to make a single-sided board so the first thing to do is set the preferred direction for the top layer to na not applicable the other thing you may need to change is the routing grid this defaults to the same default grid as the board layout editor in general 0.05 inches 1.27mm since i have my editor set up in metric since this particular board has big parts and we haven t moved any off the default grid we re ok with that value if you have smt components or have moved things around on a finer grid you might have pads that are not on the touing grid which the autorouter doesn t like much unreachable pad etc you can make the grid very small but it will take longer imo it s better to start with a coarse grid and halve it each time it looks like routes fail because the grid is too large also note that the autorouter obeys the board dimension lines so if you haven t moved them close to your components you might have traces travel all over the board or if you ve moved the outline too close to the pads you may have prevented traces from going places they need to go http www.instructables.com/id/turn-your-eagle-schematic-into-a-pcb print 7/2/2008

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instructables print turn your eagle schematic into a pcb generated by foxit pdf creator © foxit software http www.foxitsoftware.com for evaluation only página 11 de 19 i step 12 route remaining tracks manually the autorouter did a pretty nice job here there s only one trace left there are a couple of ways we could route this signal manually including some snakey routes between transistor pins that the autorouter didn t use because of the design rules we specified this is a relatively high current trace and i decided that i won t manually violate the design rules either instead i ll use a jumper wire on the component side which i can model in eagle as a top-side trace select the route tool and click on an endpoint of an unrouted yellow airwire and you can position a trace pretty much anywhere you want selecting width layer and type of bend from the menu bar as you go along this is shown in the succession of pictures in this step http www.instructables.com/id/turn-your-eagle-schematic-into-a-pcb print 7/2/2008

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instructables print turn your eagle schematic into a pcb generated by foxit pdf creator © foxit software http www.foxitsoftware.com for evaluation only página 12 de 19 i step 13 add power plane polygons power planes are large areas of copper that carry an actual signal usually power and ground on multi-layer boards it s common to have entire layers mostly dedicated to such a power plane even on a single layer board there are some advantages to doing something similar 1 use less etchant 2 carries heavier current just in case 3 makes it easier to attach test leads 4 acts as a sort of static barrier to fingers in eagle such large signal areas are drawn with the polygon command there is an icon on the toolbar for drawing polygons but it will create polygons associated with a new signal and i find that when creating a polygon for an existing signal it s easier to type the text form of the command in the text command area to create a polygon attached to a signal named gnd type poly gnd by giving it a signal name in the command the polygon will automatcailly be connected to that signal if you draw a polygon with the icon you can connect it to a signal later by using the name command to rename the polygon however after this you can t rename the polygone again without renaming the signal as well http www.instructables.com/id/turn-your-eagle-schematic-into-a-pcb print 7/2/2008

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instructables print turn your eagle schematic into a pcb generated by foxit pdf creator © foxit software http www.foxitsoftware.com for evaluation only página 13 de 19 i step 14 add v polygon now we ll repeat the process for the positive voltage however we never named that signal when we drew the schematic so it will have some random name like n$23 we can use the info command to find the signal name to use when we draw the polygon after which it s the same as drawing the gnd polygon in this case the v signal is named n$1 so we type poly n$1 http www.instructables.com/id/turn-your-eagle-schematic-into-a-pcb print 7/2/2008

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instructables print turn your eagle schematic into a pcb generated by foxit pdf creator © foxit software http www.foxitsoftware.com for evaluation only página 14 de 19 i step 15 neaten up smash package text if we want the names of components to be legible on the top of the board transferred via toner transfer or just to look good on printouts they names and values probably have to be moved from their default locations in order to move the text separately from the device itself we use the smash command why is it called smash i dunno select the smash icon from the menu then click each component whose text you want to move if this is all of the components there s a ulp that will smash everything but ulps are a subject for possible future instructables or the eagle manuals http www.instructables.com/id/turn-your-eagle-schematic-into-a-pcb print 7/2/2008

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instructables print turn your eagle schematic into a pcb generated by foxit pdf creator © foxit software http www.foxitsoftware.com for evaluation only página 15 de 19 i step 16 neaten up move traces we can move some of the traces so they look neater offer better clearance etc also we shrink the board to its final size ny squishing the components together some more http www.instructables.com/id/turn-your-eagle-schematic-into-a-pcb print 7/2/2008

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