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rp181

Wed Jun 06 2012, 04:53AM

Registered Member #1062 Joined: Tue Oct 16 2007, 02:01AM
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Posts: 1529

Agreed. LT Spice served well when designing a 64 channel transimpedance amplifier for a low light sensor, and I've used eagle to design and fab PCB's up to 12 layers. I think this is a case where you can achieve high productivity once you learn to use the tools efficiently (i.e. set shortcuts that suit you).
I recently bought Eagle 6.2, and the ability to copy consistant board layouts and schematic sure would have saved time when doing a 64 channel system...

Steve Conner

Wed Jun 06 2012, 08:14AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

I've used Eagle and LTSpice to make commercial products that are on sale.

Eagle is popular with smaller companies, and you can easily recognise an Eagle board by the ugly font in the silkscreen. I've seen it inside a Concept 2 rowing machine, the Benchmark DAC1, and the key fob transmitter for my car.

Beware when upgrading to Eagle 6, once you have edited a file from previous versions of Eagle, it gets converted to v6 format and you can't open it in the old version any more. The early 6.x releases had bugs, so some users were left with board files that they couldn't edit in either v5 or v6.

I presume they fixed that by 6.2, but it convinced us to stick with 5.x for the time being.

Neet Studio

Wed Jun 06 2012, 01:27PM

Registered Member #4037 Joined: Fri Jul 29 2011, 03:13PM
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Posts: 86

LTSpice's GUI is not as bad as some of its one-person-job peers. It is stable and functional and doesn't smell like some cross platform non-native GUI toolkit.

It is rare that a person that knows enough of the math skills and programming skills would also be able to do a proper GUI design for the people who uses it. A lot of the software people that can write GUI have no clue that their idea of "beautiful" GUI get into the way of someone actually trying to use it.
e.g. web feedback boxes that are too small to type, tab only interface for people that sometime needs to compare multiple windows side by side etc. Then there are ones that would lives in the 1980's and writes command line interface.

HV Enthusiast

Wed Jun 06 2012, 02:47PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
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Posts: 3068

Steve Conner wrote ...

The LTSpice UI isn't "awful", it just doesn't follow the Windows conventions. Ctrl-C to copy and so on.

Eagle is another program with a weird copy and paste function.

Yeah, tell me about it. I love EAGLE, but its interface is quirky.

EAGLE is not really just for small companies. I know many defense companies that use it within the engineer departments for prototyping etc... The beauty is that is a pretty powerful program and at a very good price. The license is only $1000 bucks for schematic / pcb program which is DIRT CHEAP as far as PCB program goes. Look for a seat of PCAD or Altium, and your talking $5000+ per seat depending on features you get.

Neet Studio

Wed Jun 06 2012, 10:25PM

Registered Member #4037 Joined: Fri Jul 29 2011, 03:13PM
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Posts: 86

Defense contractors trying to save money. What has this world came to?

I did a protoboard for my last job at home. It took me less than 2 nights for the layout in EagleCAD and 1 night for toner transfer single side PCB (with a full ground plane on the back). We had one overworked PCB layout person there and when you factor in the 2-3 days of his time, ordering and 5 days or so for PCB shop that's easily 2 weeks before you get your board back.

On the other hand I cannot import/reuse my schematic/layout as is to the proper system. That isn't a big problem as it took me less than 1 week to do that. I introduced LTSpice to the rest of the engineers in a previous project there and used it a lot in that design. The design/proto/simulation/test cycle took 2+ months and I had to do quite a bit of learning current mode power supply design. Most of my time is actually spent on the simulation to tweak the design instead of in the lab. Once I had the simulation showing the same problems I seen in the lab, solving it was easy as I can easily do 20-30 runs in an afternoon in LTSpice vs days in the lab. I used LTSpice for the SMPS design and for simulating the protection circuits under transients/surge conditions which are part of the compliance test.

I had worked with the mechanical designers on the power estimates, thermal and mechanical design on day one. When the schematic was done, the rest went very smoothly. I had the whole thing wrapped up and passed emission/compliance first go on first board rev. in less than 6 months.

The other supposed more experienced guy used the PCB person, had the tech solder in the proto and spent nights in the lab tweaking/hacking and finished his in about 9 months.

Steve Conner

Thu Jun 07 2012, 07:12AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

We recently decided to outsource our PCB layout to a contractor, after years of doing it ourselves in Eagle. He prefers PADS, so I wrote a converter script for Eagle that outputs a netlist in PADS format. It actually works better than you would expect, and we've done several successful boards this way.

I also spent some time working on the BOM generation. We now have a database of all the parts we use, and it will spit out the Digikey and Farnell part numbers, prices and so on.

Shrad

Thu Jun 07 2012, 07:43AM

Registered Member #3215 Joined: Sun Sept 19 2010, 08:42PM
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Posts: 780

Neet Studio wrote ...

Defense contractors trying to save money. What has this world came to?

They just use one of the best softwares available for the job...

I defy anyone to find something Eagle cannot do which others can, which is essential to the job (except ultra specialized job)

Steve Conner

Thu Jun 07 2012, 08:13AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Well, it couldn't duplicate blocks of circuitry until v6.

And the library of PCB footprints provided is full of mistakes: half of them fail Eagle's own design rule check because the silkscreen goes over the pads.

I've never tried routing a BGA in Eagle, but I once had to make a BGA footprint and the layout editor let me do it without typing out the names of each of the 272 pads.

Neet Studio

Thu Jun 07 2012, 11:18AM

Registered Member #4037 Joined: Fri Jul 29 2011, 03:13PM
Location:
Posts: 86

>I defy anyone to find something Eagle cannot do which others can, which is essential to the job (except ultra specialized job)

Challenge accepted. Not sure what is defined as " ultra specialized job". It is not like we were building microwave RF amplifier. Okay we use 3.125GHz serdes links, but they were hand routed anyways.

Let me put it this way, one of the project I was in for a place that no longer exists, Cadence has to increase the upper limits for their Concept HDL specifically for us. The schematic alone was over 120 pages and they are not blank sheets either. We were using Cadence Allegro as the autorouter.

We had a small team of us doing schematic capture at the same time on different sections of the design (each person work on 30-40 pages) while layout people was doing theirs. EagleCAD does not allow for concurrent work flow.

The monster was 26 layers board and size was about the screen of my old 19" CRT. There were 9 power supplies on the board and 5 or (6?) on a daughter card to power the different core and IO rails for the chips.

So yes, there are Big Jobs that EagleCAD cannot do.

Basic day to day things that are not in EagleCAD GUI:
measurement tool for distances between objects (or vertexes) - pretty useful for checking high voltage safety. etc
measurement for track lengths - pretty useful if you have to figure the delay skews.

Layout:
import gerber files into a layout. Let's say an easy example: a PCB antenna reference design in gerber that the vendor provided for an RF ID tag. You can either import that into the layout program or hand draw it in EagleCAD layout. :P

High end stuff: (stuff that even the big guys don't always get it right)
hierarchical design - let say you are building a PCB for a big robot, you want to define the stepper motor driver circuit as a high level "component" once with its own symbol and "pinouts". You can then use that symbol as if it were a component elsewhere in the same design.

HV Enthusiast

Thu Jun 07 2012, 02:50PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

With EAGLE, you can import DXF files into layout. But, yes, with RF circuitry, EAGLE is terrible - especially doing patch antennas and other RF stripline features etc...

Plus, you can't make a polygon surface mount pad in EAGLE yet.

But if you're doing just simple thru-hole or SMT, it works great. And the interface isn't too bad. Look at MENTOR Graphics which most defense contractors use for their production layout. MENTORs interface makes EAGLE's interface look like state of the art!!!

PCB programs are all great and i would love to try others, but the hardest thing is not learning the actual program, but migrating all your libraries over to a new program. Thats where the real investment in trying a different program is.

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