How do you design these days?
in [Design]
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From: Fred Bartoli on 1 Jan 2010 11:59 Joerg a �crit : > John Larkin wrote: >> On Thu, 31 Dec 2009 11:49:37 -0800, Joerg <invalid(a)invalid.invalid> >> wrote: >> >>> John Larkin wrote: >>>> On Wed, 30 Dec 2009 20:02:02 -0800, D from BC >>>> <myrealaddress(a)comic.com> wrote: >>>> >>>>> On Wed, 30 Dec 2009 20:01:39 -0600, "RogerN" <regor(a)midwest.net> >>>>> wrote: >>>>> >>>>>> When I was in school components fit on solderless breadboards and >>>>>> we made circuits using breadboards, power supplies, meters and >>>>>> oscilloscopes. Many of today's components don't appear to be >>>>>> breadboard friendly, so how is it done today? >>>>>> >>>>>> Is circuit design software and simulation good enough to go >>>>>> straight to a PC board? Or do you use surface mount to breadboard >>>>>> adapters? Do you still use a soldering Iron to solder or paste >>>>>> solder and an oven? >>>>>> >>>>>> I'm wanting to tinker with some circuits but some chips I'm >>>>>> interested in only comes in MSOP or other packages that look >>>>>> intimidating to attempt to solder. >>>>>> >>>>>> Thanks! >>>>>> >>>>>> RogerN >>>>>> >>>>> My motto: >>>>> If it works on a breadboard, it's not worth producing. >>>>> >>>>> On my current project, I have to feed the simulator pcb parasitics and >>>>> component parasistics to get accurate simulations. >>>>> I've had to bench test to get some parasitics. Once parasitics are >>>>> included, scope results and simulation results get close. >>>>> >>>>> If all looks good on sim, I make a pcb, etch it and bench test it. >>>> One problem is that device models often aren't available for fast >>>> parts, or all you get are S-params when you need large-signal >>>> time-domain stuff. So sometimes you can learn a lot by hacking some >>>> FR4 and testing parts. >>>> >>>> I never breadboard entire products, or even complex circuits... just >>>> enough to characterize parts or simple subcircuits. >>>> >>>> This is an EL07 driving a PHEMT... >>>> >>>> ftp://jjlarkin.lmi.net/BB_fast.JPG >>>> >>>> which made decent 5-volt, 1 GHz square waves. >>>> >>> How do you get those nice clean cuts into the copper? >> >> Just x-acto. The magic trick is to then rub it hard with a Scotchbrite >> pad. That removes the burrs. >> > > Wow, that is a precise X-acto cut. > Xactly -- Thanks, Fred.
From: Joerg on 1 Jan 2010 12:00 Fred Abse wrote: > On Fri, 01 Jan 2010 00:00:40 -0500, Spehro Pefhany wrote: > >> On Thu, 31 Dec 2009 09:10:22 -0700, the renowned Don Lancaster >> <don(a)tinaja.com> wrote: >> > > <snip> > >>> It is NEVER right the first time. >> Keep firing people who have that attitude and it eventually will be! >> >> > > Because you'll be doing it all? > Old Chinese saying: "Man who says it cannot be done should not interrupt man doing it" :-) -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Spehro Pefhany on 1 Jan 2010 12:37 On Fri, 01 Jan 2010 07:20:44 -0800, the renowned Fred Abse <excretatauris(a)invalid.invalid> wrote: >On Fri, 01 Jan 2010 00:00:40 -0500, Spehro Pefhany wrote: > >> On Thu, 31 Dec 2009 09:10:22 -0700, the renowned Don Lancaster >> <don(a)tinaja.com> wrote: >> > ><snip> > >>> >>>It is NEVER right the first time. >> >> Keep firing people who have that attitude and it eventually will be! >> >> > >Because you'll be doing it all? No, but, more seriously, there is some correlation between creativity/intelligence and a kind of disinterest in actually implementing all of the boring details with precision (and probably also ability to be managed, but that another story), so you have to be careful. *Unfounded* optimism is fatal too- one has to be particularly suspicious of data sheet claims and what evils they may be hiding behind their happy headlines. And suspicous of boring stuff such as the accuracy and applicability of stock layout libraries. If one really cares about getting things right, one can work around personality by devising checklists and such like that cover off checking for problems that have occurred in the past-- Kaizen. And don't hire people who think it takes three board spins to get rid of most of the fly wires. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff(a)interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
From: John Larkin on 1 Jan 2010 12:50 On Fri, 01 Jan 2010 08:49:20 -0800, Joerg <invalid(a)invalid.invalid> wrote: >John Larkin wrote: >> On Thu, 31 Dec 2009 19:28:42 -0800 (PST), "miso(a)sushi.com" >> <miso(a)sushi.com> wrote: >> >>> On Dec 31, 12:50 pm, Joerg <inva...(a)invalid.invalid> wrote: >>>> Phil Hobbs wrote: >>>>> On 12/30/2009 9:20 PM, Joerg wrote: >>>>>> RogerN wrote: >>>>>>> When I was in school components fit on solderless breadboards and we >>>>>>> made circuits using breadboards, power supplies, meters and >>>>>>> oscilloscopes. Many of today's components don't appear to be >>>>>>> breadboard friendly, so how is it done today? >>>>>> I even used bare thumbtacks on plywood for solder posts back then. >>>>>>> Is circuit design software and simulation good enough to go straight >>>>>>> to a PC board? Or do you use surface mount to breadboard adapters? Do >>>>>>> you still use a soldering Iron to solder or paste solder and an oven? >>>>>> In the professional world (product design) we go straight from >>>>>> simulation to schematic -> layout -> board fab -> assembly. No >>>>>> breadboards. >>>>>>> I'm wanting to tinker with some circuits but some chips I'm interested >>>>>>> in only comes in MSOP or other packages that look intimidating to >>>>>>> attempt to solder. >>>>>> Well, for hobbyists or one-off designs there is help but not very cheap: >>>>>> http://www.proto-advantage.com/store/images/PRODUCTS/PA0027_0.JPG >>>>>> This is the variety they have but I don't know this shop, just meant as >>>>>> an example: >>>>>> http://www.proto-advantage.com/store/index.php?cPath=2200 >>>>> _THE_ professional world? Joerg, Joerg, you've been holed up in that >>>>> mountain lair of yours for too long. ;) >>>> Now, now, we do have a modern feed store in this here town whar we're >>>> gitten them alfalfa bales and all that, and they even use a computation >>>> machine :-) >>>> >>>>> Simulate the parts that simulators get right, do the rote stuff by rote, >>>>> but prototype the stuff you're not sure will work. It's amazing the >>>>> amount of stuff you can learn in a short time from a dead-bug prototype. >>>>> If you're just talking about laying out boards for circuit prototypes, >>>>> then I agree--you might as well try a bit harder and get it right the >>>>> first time. But trying out weird stuff, especially in mixed-technology >>>>> systems, really needs prototypes. >>>> Ok, I did build a breadboard for my first noise-critical fiber-optics >>>> front end but that was more because the client really wanted that done. >>>> I ended up not changing a thing on there and going straight to a >>>> multi-channel layout. Since it has digital delay controls with SPI and >>>> stuff it (almost) counts as mixed signal. >>>> >>>>> Besides, lots of my protos are actually small instruments that I build >>>>> in half a day and then use for years. An example is the sub-Poissonian >>>>> current source and LNA I built for my tunnel junction work--very >>>>> specific, worked great for years, took a day all told to design and >>>>> build. Good medicine. >>>> One-off things I also often build on experimental board. I am not a >>>> great friend of the dead-bug style, preferring Vector board with a >>>> ground plane. That's harder to find these days so I stocked up. Many >>>> things go into those little Pomona boxes that end up riding on the back >>>> of a coax connector. All good medicine, but at least I can put a shiny >>>> aluminum lid on it so the clients don't see the wire ball inside my probes. >>>> >>>> -- >>>> Regards, Joerg >>>> >>>> http://www.analogconsultants.com/ >>>> >>>> "gmail" domain blocked because of excessive spam. >>>> Use another domain or send PM. >>> Vector board is insanely priced. I buy it up at flea markets when I >>> find good deals and nibble out small pieces for circuits to conserve >>> it. I think if I had to pay real prices for vectorboard, I'd use the >>> on-line PCB manufacturers. I dead bug too. >>> >> >> Live bug is easier to visualize. And if you work on copperclad, you >> can bend ungrounded pins out horizontally and solder the groudable >> pins directly to the plane. >> > >Also, you can bend all the pins up to achieve a living bug. Usually, and >only once. I often take a snippet of thin wood, glue that down, glue the >chip onto that and then solder all the pins that need GND to the copper. >This avoids any pin bending. With wood it's still possible to swap the >chip when you have fried it, not so easy with plastics. Plus gives me a >wonderful excuse to eat a Haagen-Dasz bar with almond crunch on top :-) > > >> Kapton tape is great, too, when working on copperclad. >> > >Yup. The only thing I hate with copper clad is all the ugly fingerprints >after hours of experimenting. One of these days I'm going to have a board house gold-plate a bunch of FR4 scraps. Boy would you guys have breadboard envy! John
From: John Larkin on 1 Jan 2010 12:53
On Fri, 1 Jan 2010 08:58:03 -0800 (PST), Bill Sloman <bill.sloman(a)ieee.org> wrote: >On Jan 1, 6:00�am, Spehro Pefhany <speffS...(a)interlogDOTyou.knowwhat> >wrote: >> On Thu, 31 Dec 2009 09:10:22 -0700, the renowned Don Lancaster >> >> >> >> >> >> <d...(a)tinaja.com> wrote: >> >John Larkin wrote: >> >> On Thu, 31 Dec 2009 14:01:44 -0000, "markp" <map.nos...(a)f2s.com> >> >> wrote: >> >> >>> "RogerN" <re...(a)midwest.net> wrote in message >> >>>news:ROudnXLvg9-Tm6HWnZ2dnUVZ_oidnZ2d(a)earthlink.com... >> >>>> When I was in school components fit on solderless breadboards and we made >> >>>> circuits using breadboards, power supplies, meters and oscilloscopes. >> >>>> Many of today's components don't appear to be breadboard friendly, so how >> >>>> is it done today? >> >> >>>> Is circuit design software and simulation good enough to go straight to a >> >>>> PC board? �Or do you use surface mount to breadboard adapters? �Do you >> >>>> still use a soldering Iron to solder or paste solder and an oven? >> >> >>>> I'm wanting to tinker with some circuits but some chips I'm interested in >> >>>> only comes in MSOP or other packages that look intimidating to attempt to >> >>>> solder. >> >> >>>> Thanks! >> >> >>>> RogerN >> >> >>> I tend to design a PCB with CAD software then have prototype PCBs made. >> >>> There are several companies out there who do 'pooling', i.e. they amalgamate >> >>> many designs onto one PCB, that way you end up only paying a small fraction >> >>> of the tooling cost of the PCB. Some companies can handle 6 layer boards >> >>> with this process. Example in the UK is PCB Snap from Spirit Circuits >> >>> (www.spiritcircuits.com). >> >> >>> This can be quite cost effectve for producing protptypes that are as close >> >>> to the final product as practicable. >> >> >> Why not go for the real thing, first time? If you get it right, you >> >> can sell it. >> >> >> John >> >> >It is NEVER right the first time. >> >> Keep firing people who have that attitude and it eventually will be! > >Perhaps. But if the survivors are sufficiently nervous of getting >fired that they triple-check every aspect of the circuit before they >commit to a printed circuit layout, you may find that you get to the >final layout more slowly than you would have if you'd gone through a >throw-away prototype layout along the way. Even better is to have the survivors enjoy their work and their lives, and do good work because they like to. Getting it right, and beautiful, becomes a team sport. There's no limit to how many throw-away prototypes you can do, at least until the project is cancelled. John |