How do you design these days?
in [Design]
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From: John Larkin on 1 Jan 2010 13:43 On Fri, 01 Jan 2010 14:06:02 GMT, Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote: >On a sunny day (Thu, 31 Dec 2009 18:13:00 -0800) it happened John Larkin ><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in ><q9mqj5dsgr3mvime8j2brar18l538grq67(a)4ax.com>: > >>>Real man use no PeeSeeBee: >>> ftp://panteltje.com/pub/z80/graphics_card_top.jpg >>> ftp://panteltje.com/pub/z80/graphics_card_bottom.jpg >>>:-) >>> >> >>ACK! We were going out for beer and burgers, but you just killed my >>appetite. >> >>This is more like it. The bottom board is my one-off signal >>conditioner/relay driver. And I built a spare. >> >>ftp://jjlarkin.lmi.net/Auto_plate.jpg > > >It looks very nice, but those screw terminals... >I have had some molten ones, probably because I used those at 10 A. >Am I imagining it, or are there awfully small traces going to those terminals? The ones on the left go to 1K platinum RTDs. The ones on the right are relay contacts to pretend to be a thermostat to our gas furnace. Top are digital and analog interfaces to the Integrity board. All low current, powered by a 12-volt wart and an LM7805 on the upper board. >*Fusible* traces? ;-) >Would not a few real connectors be easier? Not to connect field wiring. >My LM135 temp sensors ends in a stereo phono plug, as do all other sensors.. >ground, +5 fed via a resistor, and signal. >The same way I drive LEDs. >So I just plug the sensors in like a headphone, and can easily swap each. I'm getting a couple tenths of a degree C accuracy from the RTDs. The measurement and math are ratiometric against some 1K 0.1% resistors. Incidentally, I recommend this gadget http://www.rs-485.com/daqitemw.asp?record=95 for projects like this. It works as advertised and is easy to use. I expected to have to do some signal averaging on my temperature acquisition, but it's dead stable without. Of course, the braid+foil shielded RG174 runs to the RTDs may have helped. > >The digital inputs / output are driven by a PCF8574 (bidirectional i2c I/O expander), >and the inputs by a PCF8591, a 4 channel i2c 8 bit AD + DA converter. >The i2c hands on 3 pins of the PC par port. >In the original design there was a local LCD driven by 2 PCF8574 remotely too. >No RS232 then. >This has been working since the eighties without problems, >but I accidently killed the LCD (main wire dropped on a data line), and took it out. I got 100% spares for this project, and a bunch of bare boards for free, so it should last. Absolutely *everything* about this project worked as expected, first time. Except the software, of course. The hardware I planned and checked. The software, I just sat down and started typing. I had a little trouble shelling out to the FTP stuff while running the realtime part, which I fixed by writing a separate program to do the ftp transfers. The hard part was pulling the wires. >The original soft was also in BASIC, MCS BASIC on a 8052 ! >Anybody remember MCS BASIC? >Then rewrote it in C, and ported to CP/M. >That C ported to DR DOS. >That DOS C ported to Linux. >And it still works today:-) >Recently I added a temp PIC temp sensor via an USB to RS232 adaptor, > http://panteltje.com/panteltje/pic/temp_pic/index.html >if that sensor fails (is not connected) the software detects it, and switches back to the LM135. >Interesting to write the soft that detects all the possible USB errors, finally >had to have it check the data format the temp_pic sends, to make sure >USB enumeration had not caused some other sensor to be read.... Yeah, I had to consider all sorts of failure modes so that the heat wouldn't stay on full-blast for weeks. >i2c was and is, a lot simpler, not sensitive to random delays due to multi-tasking OS either. >temp_pic sensor is cool, had it in the fridge to -18, and in boiling water to 100 C. > The semiconductor sensors usually aren't very accurate. The RTDs are fantastic. I can't imagine how they calibrate them in production. I considered the Z-wave home automation stuff, but their temp sensors only go down to 40F and are of unknown accuracy. Plus, I wouldn't have long-term maintainability, and remote access could be a problem. And I wouldn't have had a project for this week. Here it is installed in the ski-boot closet. All I have to do is wire up the furnace control and clean things up. ftp://jjlarkin.lmi.net/Auto_wired.jpg Needs more tie-wraps. John
From: Spehro Pefhany on 1 Jan 2010 14:01 On Fri, 01 Jan 2010 09:00:57 -0800, the renowned Joerg <invalid(a)invalid.invalid> wrote: >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" :-) I tend to manage along the lines of McGregor's 'Theory Y', but not every person responds umm.. 'optimally' to that level of autonomy. 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: Joerg on 1 Jan 2010 14:10 Spehro Pefhany wrote: > On Fri, 01 Jan 2010 09:00:57 -0800, the renowned Joerg > <invalid(a)invalid.invalid> wrote: > >> 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" :-) > > I tend to manage along the lines of McGregor's 'Theory Y', but not > every person responds umm.. 'optimally' to that level of autonomy. > Strongly agree. The only times I deviated from "Theory Y" was when employees or a group could not arrive at a decision by the time it was due. Then I made the decision instead which occasionally p.o.'ed people but it had to be done. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: John Larkin on 1 Jan 2010 14:18 On Fri, 01 Jan 2010 18:33:34 +0000, John Devereux <john(a)devereux.me.uk> wrote: >Bill Sloman <bill.sloman(a)ieee.org> writes: > >> 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. > >I'm going through this right now. New (208 pin!) microcontroller, ADC, >connectors, SMPS chip. I can spend an extra couple of days re-checking >everything, and I just *know* I will still miss a couple of things. Or I >can just go ahead and make the damn board. > >I think I'll just go ahead and see how it turns out. At some point it's >actually quicker and cheaper to debug using the real thing. You have to debug the real thing anyhow, so it makes sense to try to do the final product first pass. That saves a lot of time and teaches good disciplines. And you may be able to sell it. John
From: John Larkin on 1 Jan 2010 14:18
On Fri, 01 Jan 2010 13:40:32 -0500, Phil Hobbs <pcdhSpamMeSenseless(a)electrooptical.net> wrote: >On 1/1/2010 1:10 PM, John Larkin wrote: >> On Fri, 01 Jan 2010 11:28:56 -0500, Phil Hobbs >> <pcdhSpamMeSenseless(a)electrooptical.net> wrote: >> >>> On 1/1/2010 10:20 AM, Fred Abse wrote: >>>> On Fri, 01 Jan 2010 00:49:11 +0000, Jan Panteltje wrote: >>>> >>>>> It is 'bison kit', or translated 'Bison Glue'. >>>> >>>> What is the difference between a buffalo and a bison? >>> >>> Like "What's the difference between a Stoic and a Cynic? >>> >> >> I couldn't care less. >> >> John >> > >Snow a bit heavy, is it? ;) Cold means nothing to me. John |