Post by thread:[EE] Fun blunders

Alan B. Pearce wrote: >> "When making an Eagle package, don't take the pin >> numbers from a diagram in the data sheet that shows >> the package... upside down..." > > yeah, its a bit hard to put surface mount packages on the other side of the > board to the pads. Oh, it's simple if you don't mind flipping the LED modules upside down... Makes them a bit hard to see, but so what... > Bring back Through Hole Components I say. ....... Yeah! I prefer the feel of a boom box cassette player over an iPod any day. :) -- Timothy J. Weber http://timothyweber.org

Peter Todd wrote: > "Print out a 1:1 copy of your gerbers and see if the mounting holes on > your board are in the same galaxy as the ones on your associated LCD > screen... idiot." Yes, I've made that rule for myself. Several times. Still don't follow it... > Nice... I caught myself happily laying out traces to an IC recently on a > complex double sided board, LED digits on one side, smd parts on the > other. Unfortunately said IC and the digits were on the same side... > stupid xpcb and it's lack of keepouts... Scotty said we canna change the laws o' physics, but some days I'd settle for a slight change in the laws of geometry. -- Timothy J. Weber http://timothyweber.org

My father (a house builder) had an older generation carpenter working for him. He said "I don't know what's wrong, I cut the wood board off twice and it's still TOO SHORT!" Timothy J. Weber wrote: {Quote hidden}> Alan B. Pearce wrote: > >>> "When making an Eagle package, don't take the pin >>> numbers from a diagram in the data sheet that shows >>> the package... upside down..." >>> >> yeah, its a bit hard to put surface mount packages on the other side of the >> board to the pads. >> > > Oh, it's simple if you don't mind flipping the LED modules upside > down... Makes them a bit hard to see, but so what... > > >> Bring back Through Hole Components I say. ....... >> > > Yeah! I prefer the feel of a boom box cassette player over an iPod any > day. :) >

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Wed, Jun 20, 2007 at 05:51:23PM -0400, Timothy J. Weber wrote: {Quote hidden}> Peter Todd wrote: > > "Print out a 1:1 copy of your gerbers and see if the mounting holes on > > your board are in the same galaxy as the ones on your associated LCD > > screen... idiot." > > Yes, I've made that rule for myself. Several times. Still don't follow > it... > > > Nice... I caught myself happily laying out traces to an IC recently on a > > complex double sided board, LED digits on one side, smd parts on the > > other. Unfortunately said IC and the digits were on the same side... > > stupid xpcb and it's lack of keepouts... > > Scotty said we canna change the laws o' physics, but some days I'd > settle for a slight change in the laws of geometry. Oddly enough on that same I ended up kinda changing the laws of geometry, or at least layout. See, these are rather large, current sucking, 2.5" high 7 segment leds. In my usual fashion I figured I'd put one 1.5A 7808 regulator per led to drive the common anodes. But it's such a crowded board, oh where oh well will I put all those regulators? Fortunately the LEDs actually have two parallelogram shaped pockets on the backside in the middle of upper and lower boxes formed by the digit segments... - -- http://petertodd.org -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFGeasZ3bMhDbI9xWQRAv1hAKCPUX8rp/4zqEUKe5xk38h0SlFMcgCeKbBx AutYcDsqkLWG992QjHFx/yE= =5o2O -----END PGP SIGNATURE-----

Peter Todd wrote: > But it's such a crowded board, oh where oh well will I put all those > regulators? > > Fortunately the LEDs actually have two parallelogram shaped pockets on > the backside in the middle of upper and lower boxes formed by the digit > segments... Hee hee! You made a board layout joke! Best I've been able to do in that regard is to rotate a 9V battery by something like 18 degrees in order to fit it in amongst some standoffs. Fit so tightly, I didn't need to do anything extra to hold it stationary, even when you shake the case. But that was mainly serendipity. -- Timothy J. Weber http://timothyweber.org

> > "Print out a 1:1 copy of your gerbers and see if the > mounting holes on > > your board are in the same galaxy as the ones on your > associated LCD > > screen... idiot." Gerbview? Or just send the .brd file to your boardhouse (if it is Olimex), no need to gerber.... Wouter van Ooijen -- ------------------------------------------- Van Ooijen Technische Informatica: http://www.voti.nl consultancy, development, PICmicro products docent Hogeschool van Utrecht: http://www.voti.nl/hvu

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Wed, Jun 20, 2007 at 08:24:17PM -0400, Timothy J. Weber wrote: > Peter Todd wrote: > > But it's such a crowded board, oh where oh well will I put all those > > regulators? > > > > Fortunately the LEDs actually have two parallelogram shaped pockets on > > the backside in the middle of upper and lower boxes formed by the digit > > segments... > > Hee hee! You made a board layout joke! That's worse than Star Trek jokes isn't it? > Best I've been able to do in that regard is to rotate a 9V battery by > something like 18 degrees in order to fit it in amongst some standoffs. > Fit so tightly, I didn't need to do anything extra to hold it > stationary, even when you shake the case. But that was mainly serendipity. I once did that on a project too. I had to fit 64 circuit boards, each controlling a stepper motor, onto a big 2ft by 2ft plate. I'll have to admit I designed the motor driver boards first without thinking how I was gonna fit 'em all in. (hey, I was working 12-16 hours days for a month...) Of course they didn't fit length wise until I tilted them ever so slightly... http://petertodd.org/art/8-2-automaton/imgs/pcb-assembly-full.jpg - -- http://petertodd.org -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFGfGX33bMhDbI9xWQRAp6MAJ0UFKEnWZE5vJBg8fU6DEerCPtFIwCfd9aQ Xa/d3pNNDvbT0NlaeNwAheo= =8d1k -----END PGP SIGNATURE-----

Peter Todd wrote: > On Wed, Jun 20, 2007 at 08:24:17PM -0400, Timothy J. Weber wrote: >> Hee hee! You made a board layout joke! > > That's worse than Star Trek jokes isn't it? Yes, much. Or better. > Of course they didn't fit length wise until I tilted them ever so > slightly... > > http://petertodd.org/art/8-2-automaton/imgs/pcb-assembly-full.jpg It's an impressive array, and I'm glad I wasn't there for the final plugging of motors to drivers. But... are they tilted up from the horizontal, or just around the vertical axis? If it's the latter, I'm not sure I get why it helped... though it definitely looks more aesthetically interesting. -- Timothy J. Weber http://timothyweber.org

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Sat, Jun 23, 2007 at 03:29:57PM -0400, Timothy J. Weber wrote: > > Of course they didn't fit length wise until I tilted them ever so > > slightly... > > > > petertodd.org/art/8-2-automaton/imgs/pcb-assembly-full.jpg > > It's an impressive array, and I'm glad I wasn't there for the final > plugging of motors to drivers. Be glad! The leads on the motors are rather short. > But... are they tilted up from the horizontal, or just around the > vertical axis? If it's the latter, I'm not sure I get why it helped... > though it definitely looks more aesthetically interesting. Looking at it I'm not so sure either. I tried playing around with the original cad files, the boards are rotated 9.78 degrees, and the after rotation clearance from board to board is 0.05 less than before rotating it. My best guess is that after rotating the *mounting* posts have about double the clearance between them, an extra tenth of an inch. I must have been thinking how I was going to get a tool in there to tighten them. - -- http://petertodd.org -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (GNU/Linux) iD8DBQFGfem23bMhDbI9xWQRAgubAJoCzf9CYXvYRnYDk5aUkW9iffSFAQCcC0WK +0aovJf/Z4l7j26JFQIw810= =t7u4 -----END PGP SIGNATURE-----

Peter Todd wrote: >>> petertodd.org/art/8-2-automaton/imgs/pcb-assembly-full.jpg >> It's an impressive array, and I'm glad I wasn't there for the final >> plugging of motors to drivers. > > Be glad! The leads on the motors are rather short. That's what I thought! I always underestimate clearance for boards wired to one another. {Quote hidden}>> But... are they tilted up from the horizontal, or just around the >> vertical axis? If it's the latter, I'm not sure I get why it helped... >> though it definitely looks more aesthetically interesting. > > Looking at it I'm not so sure either. I tried playing around with the > original cad files, the boards are rotated 9.78 degrees, and the after > rotation clearance from board to board is 0.05 less than before rotating > it. > > My best guess is that after rotating the *mounting* posts have about > double the clearance between them, an extra tenth of an inch. I must > have been thinking how I was going to get a tool in there to tighten > them. Ah!! Now that makes sense. And maybe the mounting hole drills would be uncomfortably close together? -- Timothy J. Weber http://timothyweber.org