DIY_EFI Digest Wednesday, 25 September 1996 Volume 01 : Number 286 In this issue: Re: water/temp/mileage Re: DIY_EFI Digest V1 #285 Chip operating temperatures re: Fog Re: DIY_EFI Digest V1 #281 Re: Chip operating temperatures Re: Chip operating temperatures Re: water/temp/mileage Re: Chip operating temperatures Re: Chip operating temperatures Re: Chip operating temperatures Re: Chip operating temperatures Re: Fuel Air Diesel engine induction Re: Chip operating temperatures Re: Chip operating temperatures Re: D disease Re: Chip operating temperatures Re: Chip operating temperatures Re: Chip operating temperatures Re: Chip operating temperatures Re: 6811 Disassembler Re: water/temp/mileage See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: talltom Date: Tue, 24 Sep 1996 03:25:20 -0700 (PDT) Subject: Re: water/temp/mileage I had a new scirocco in 79 and it normally got around 25 mpg. One nippy(50s-60s) morning that was kind of foggy in places I drove 134 miles more orless on the freeway and refueled upon arrival. I just about crapped. 2.4 gallons! that's(48 mpg) the only time in the life of the car I ever saw this, and the only thing changed before or after was the weather. >- ---------- >From: tom cloud[SMTP:cloud@xxx.edu] >Sent: Friday, September 20, 1996 6:12 PM >To: diy_efi@xxx.edu >Subject: Re: DIY_EFI Digest V1 #277 > > [ snip ] > >>On a side note, I notice that a number of the water injection posts over the >>last week or so seem to imply that water injection can get more power out of >>a normally aspirated engine. I don't think that is true. > >I know on my motorcycle(s) -- they always ran noticeably better >when the humididity was hi. > >Tom > "a society that will trade a little freedom for a little order deserves neither" Thomas Jefferson Clinton doesn't want anything Hitler didn't have. What do you get with Bob Dole, Bill Clinton, and Dolly Parton in the same room? Two boobs and a country singer! Harry Browne for president 96! Talltom ------------------------------ From: talltom Date: Tue, 24 Sep 1996 04:10:17 -0700 (PDT) Subject: Re: DIY_EFI Digest V1 #285 >------------------------------ > >From: cloud@xxx.edu (tom cloud) >Date: Mon, 23 Sep 1996 08:44:43 -0500 >Subject: Re: self tuning efi > > [ snipetty - snip ] > >>I thought I was the first one to bring that idea up! Oh well. > >Yeah, but I thought of it first !! > >Tom "a legend in his own mind" Cloud Doesn't really matter, either way it's Tom's idea. I certainly don't have the money, or life expectancy needed for a patent, or the capability to put a functioning one together. I'm just hoping some of the rest around here find the idea intriguing enough to do one, and if I'm around long enough, and still have cars around maybe I'll be able to use one. Considering that the latest car I got took 24 years to get to the point I could afford it, I doubt much of it's relevent anyway. "a society that will trade a little freedom for a little order deserves neither" Thomas Jefferson Clinton doesn't want anything Hitler didn't have. What do you get with Bob Dole, Bill Clinton, and Dolly Parton in the same room? Two boobs and a country singer! Harry Browne for president 96! Talltom ------------------------------ From: "Al Grippo" Date: Tue, 24 Sep 96 20:59:34 EST Subject: Chip operating temperatures IC chips for automotive use are generally specified as having operating temperatures from -40 deg C to 125 or 150 deg C. The 68332 chips bought in the group pcb buy were rated 0 deg C to 70 deg C (32 deg F to 158 deg F). I'm sure these are ok for prototypes, but is anyone concerned about them lasting 50-100 k miles in a real environment ? Most of the critical parts for the board which I have accumulated are in the automotive temperature range, but I have not been able to get the 68332 or sram chips in this range. I know the part numbers, but was told by several major suppliers (newark, future, hallmark) that these industrial/ milspec chips are not stock items and must be ordered in large quantities. The same applies to sram (the highest industrial range here is -40 deg C to 70 deg C). Is anyone interested in a group buy for these ? Al Grippo ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Tue, 24 Sep 1996 08:08:23 -0500 Subject: re: Fog >> Temperature didn't make as much difference as fog! > >Fog increases the specific heat of air. This will increase the charge >density simply because the air is absorbing the same heat (from the >inlet system) but will have a lesser increase in temperature, hence >greater density. wha'd he say? it all works out the same, seems t' me -- raise the humidity, get power increase -- i don't imagine it, works at any temp, mebbe this is why so many folks are asking about water injection ?? ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Tue, 24 Sep 1996 08:16:40 -0500 Subject: Re: DIY_EFI Digest V1 #281 [ snippy ] >> Clinton doesn't want anything Hitler didn't have. > >You know as much as I'm against the Clintons, I don't think this list it >the place for the political BS. > >John Faubion Oh, lighten up !! ------------------------------ From: Jay Snyder Date: Tue, 24 Sep 1996 10:01:44 -0400 (EDT) Subject: Re: Chip operating temperatures On Tue, 24 Sep 1996, Al Grippo wrote: > IC chips for automotive use are generally specified as having operating > temperatures from -40 deg C to 125 or 150 deg C. The 68332 chips bought in the > group pcb buy were rated 0 deg C to 70 deg C (32 deg F to 158 deg F). I'm sure > these are ok for prototypes, but is anyone concerned about them lasting 50-100 > k miles in a real environment ? > > Most of the critical parts for the board which I have accumulated are in the > automotive temperature range, but I have not been able to get the 68332 or sram > chips in this range. I know the part numbers, but was told by several major > suppliers (newark, future, hallmark) that these industrial/ milspec chips are > not stock items and must be ordered in large quantities. The same applies to > sram (the highest industrial range here is -40 deg C to 70 deg C). Is anyone > interested in a group buy for these ? > > Al Grippo Commercial Temp's should be OK if you mount the computer in the passenger side of the firewall. Most ECM's are above/behind the glove box, and others are under one of the front seats. J. ------------------------------ From: Sandy Date: Tue, 24 Sep 1996 08:43:50 -0700 Subject: Re: Chip operating temperatures At 08:59 PM 9/24/96 EST, you wrote: > IC chips for automotive use are generally specified as having operating >temperatures from -40 deg C to 125 or 150 deg C. The 68332 chips bought in the >group pcb buy were rated 0 deg C to 70 deg C (32 deg F to 158 deg F). I'm sure >these are ok for prototypes, but is anyone concerned about them lasting 50-100 >k miles in a real environment ? > I mentioned this problem a while ago. The solution became to not mount the processor under the hood. Not the best, but solves much of the heat problem. Even that still can be on the edge of the temperature extreems. Sandy ------------------------------ From: "Robert Harris" Date: Tue, 24 Sep 1996 09:11:31 -0700 Subject: Re: water/temp/mileage Got new asbestos underwear, so try these thoughts on for size Given: A: The two major products of combustion are carbon dioxide and water B. You make two gallons of water for every gallon of gasoline you burn C: The partial pressure contributed by steam is much higher than that contributed by CO2 or N2 (the other major gas's present) D: You have at least 65 to 70% of the heat released in combustion available as EXCESS heat (i.e. not converted to mechanical energy) E: You want the means to precisely meter the fuel (or why would you be subscribing to this list) and any other engine things - like adding water injection. Contemplate A: Since combustion makes vast quantities of steam where there was no water before, and steam has a good percentage of the partial pressure perhaps it might have something to do with BMEP B: Brake Mean Effective Pressure (BMEP) might have some vague relationship to power, torque, mechanical energy developed C: If A and B has any truth, perhaps adding a little bit more water might make a little bit more contribution to BMEP by converting some EXCESS heat to some MORE steam. Your Options: A: Flame the author. If it was not documented by some European dude 40 years ago it must not work or can't be possible or can only work the way the dead dude said prior to the onset of senility or technology. B: Trash the idea, if you haven't heard about it being widely used it ain't going to work anyway. C: Ignore the physics and chemistry of the whole proposition and throw out a whole bunch of ninny so theres and can't be's and apples to road apples comparisons. D: Calculate: Assuming 30 (damned good) percent conversion chemical to mechanical energy 70% Excess heat available. Convert 10% of the EXCESS heat to mechanical energy. That means an addition 7% total conversion by using a heat recovery mechanism. Total engine conversion is now 37% a gain of 20 some percent in power from the same heat. Tell that to any racer, and before you can blink, the kids are sold into slavery, wives off to prostitution and grannies pushing a shopping cart - whatever it takes to put that to the pavement - specially since the difference between first and forget are often a single digit percent of power. E: If D intrigues you, quietly meter some water injection to the engine of your choice. Use your EFI fuel output value to get a baseline and add some injected water (properly distributed and atomized) as a linear percentage of fuel. Vary the percentage slowly upward until you find out what your engine combination likes. You know what a cool foggy day does for you. Now everyday is a cool foggy day and then some. If it makes more power and economy - keep it a secret, because Mr thermodynamics and his Greek Chorus say it can't be done Just blow their doors off and say "Pure F'ng Magic Dude.) Who really care's why why it works, as long as it puts power to the pavement. If Merlin put a spell on a double a fuel dragster and it started winning, believe me every Ricky racer would be looking for a magician. Remember Contempt before Investigation leads to a lot of lost opportunities. - ----- Cut here - personal comment follows ----- Q: What's the difference between Jane Fonda and Bill Clinton? A: She had the balls to go to Viet Nam Robert Harris - ---------- ------------------------------ From: Bruce Bowling Date: Tue, 24 Sep 1996 12:15:52 EDT Subject: Re: Chip operating temperatures > > At 08:59 PM 9/24/96 EST, you wrote: > > IC chips for automotive use are generally specified as having operating > >temperatures from -40 deg C to 125 or 150 deg C. The 68332 chips bought in > the > >group pcb buy were rated 0 deg C to 70 deg C (32 deg F to 158 deg F). I'm > sure > >these are ok for prototypes, but is anyone concerned about them lasting 50-100 > >k miles in a real environment ? > > > > I mentioned this problem a while ago. The solution became to not mount the > processor under the hood. Not the best, but solves much of the heat problem. > Even that still can be on the edge of the temperature extreems. > > > Sandy > > But what about temperatures below zero degrees? Here in the mid-atlantic area of the U.S., there are plenty of mornings where I have to scrape off the frost from the windshield, or replace the radiator because I forgot to add anti-freeze. Will the chips works in the cold region properly? - - Bruce - -- - ----------------------------------------------------- <<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> - ----------------------------------------------------- Bruce A. Bowling Staff Scientist Thomas Jefferson National Accelerator Facility 12000 Jefferson Ave - Newport News, VA 23602 (804) 249-7240 bowling@xxx.gov/~bowling - ----------------------------------------------------- <<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> - ----------------------------------------------------- ------------------------------ From: Wayne Braun Date: Tue, 24 Sep 1996 10:49:47 -0600 Subject: Re: Chip operating temperatures At 08:59 PM 9/24/96 EST, you wrote: > IC chips for automotive use are generally specified as having operating >temperatures from -40 deg C to 125 or 150 deg C. The 68332 chips bought in the >group pcb buy were rated 0 deg C to 70 deg C (32 deg F to 158 deg F). I'm sure >these are ok for prototypes, but is anyone concerned about them lasting 50-100 >k miles in a real environment ? > > Most of the critical parts for the board which I have accumulated are in the >automotive temperature range, but I have not been able to get the 68332 or sram >chips in this range. I know the part numbers, but was told by several major >suppliers (newark, future, hallmark) that these industrial/ milspec chips are >not stock items and must be ordered in large quantities. The same applies to >sram (the highest industrial range here is -40 deg C to 70 deg C). Is anyone >interested in a group buy for these ? > > Al Grippo > For prototypes, I think these parts will work fine. We can get the systems working and work the bugs out etc... It does not usually get much over +40C here so the top end of the temp range is not much of a concern. BUT, winter IS comming. It is already going down to +3C at night, and -40C is not that unusual. I for one will need parts that I can rely on to work at least down to -40C and preferrably - -50C. At -40C, things can get very serious in a big hurry and the last thing that you need is a vehicle that will not run due to the cold. Last winter there were days where the temp did not warm up to -40. I know, I know, if its that cold just stay inside, sometimes that is not an option ( my boss has this foolish notion that I should show up for work ). If you are putting together a buy, I'm in. Wayne ( I really need to find a more moderate climate ) Braun Wayne Braun Product Support Services Develcon Electronics EMAIL: Wayne.Braun@xxx.com Phone 1-800-667-9333 or ( 306 ) 933-3300 FTP://FTP.Develcon.com Standard disclaimer about speaking only for myself etc...... ------------------------------ From: Stephen Dubovsky Date: Tue, 24 Sep 1996 14:31:00 -0400 Subject: Re: Chip operating temperatures At 12:15 PM 9/24/96 EDT, you wrote: >But what about temperatures below zero degrees? Here in the mid-atlantic >area of the U.S., there are plenty of mornings where I have to scrape >off the frost from the windshield, or replace the radiator because >I forgot to add anti-freeze. Will the chips works in the cold region >properly? > >- Bruce I am an EE w/ a few years experiance so I HOPE I know what Im talking about... Most chips will work outside their temp range, but how well is another story. Most analog parts simply wont meet published specs (but when do they?) like offset, slew rate, etc. Most digital stuff still works, but the timing parameters must be relaxed. Every now and then you can find a part that wont work in the cold, but often it can be replaced (w/ another identical part). Often the automative and comercial temp ranges are the same part, but one is tested and guaranteed to the more extreme temps. The only real difference I can tell (from practical experience) is the packaging. The Mil spec stuff is almost always ceramic which may take the temp cycling better, but the comercial and auto stuff appear to be in the same plastic package (hope it doesn't crack at low temp). In a nutshell: If you derate the comercial parts they often work well outside their spec temp range. SMD Remember that your interior can get VERY hot (when your away w/ the windows rolled up) so dont assume your EFI computer will never have to work at 140F+ ambient if its in the passenger compartment (still want to be able to start your car, right? ;) Oh, and the way to keep from replacing the radiator because you forgot to add antifreeze is to use an air cooled engine;) (Im a 911 owner) ------------------------------ From: benagh@xxx.COM (Jeff Benagh ) Date: Tue, 24 Sep 96 15:06:08 EDT Subject: Re: Chip operating temperatures To paraphrase Stephen Dubovsky's comment: > In a nutshell: If you derate the comercial parts they often work well > outside their spec temp range. The chips (usually) are physically the same. If there is are several sets of parameters in the databook (comm, ind/auto, military) you can usually just use the other set of numbers. The commercial parts were not sample tested in the other temp range though. And the packaging might be slightly different. It's often quite a challenge to effectively remove heat from parts, especially when the ambient is 50C or so. In general, the cooler you run them the longer they will last, which isn't usually a factor for hobbyist types. Jeff ------------------------------ From: Gordon Couger Date: Tue, 24 Sep 1996 14:05:14 -0500 Subject: Re: Fuel Air Diesel engine induction >Gordon Couger wrote: >> >> >> Dirty little diesel secret. Propane. >> It works great. Just watch your exuast gas temperture. You can melt down >> a turbo or and engin this way. I don't know if it is still being done >> but in the 60's & 70's it was used to get you through the "hard spots" >> by some folks. If they didn't over use it they seemed to get by pretty >> well. > >what would you suggest to keep my exh-temp at ? >do you know some base-lines like max temp ? > I don't recall. But I think it is pretty well documented in almost any thing that discusses turbo chargers. >> >> One thing I wonder about with water injection is high pressure steam is >> pretty corosive stuff. I would worry about piston, valve and turbo >> errosion. > >I don't worry about it too much . I don't plan to stop the engine right >after >full throttle operation so she'll get time to get clean I am not worried so much about condensed water but the superheated steam itself. If you are running hot at all and shut down from full power you will end up with warped valves and frozen trubos if you do it very often. Gordon ------------------------------ From: "Robert Harris" Date: Tue, 24 Sep 1996 12:15:49 -0700 Subject: Re: Chip operating temperatures >From many years experience in the aerospace industry operating temperatures are much more important than storage temps. Mounting the components within the passenger compartment will keep commercial quality components well within specs regardless of outside temp. The mil-spec components price will shock your shorts off- so remember the big difference at high temps is the heat dissipation capabilities of the chips. Think not? I know many PC's that people paid top dollar for are running pushed processors (lower speed rated chips operated at higher clock speeds) with a big fan glued to the chip. Built a few myself (with the customer knowing it). I could go into why hot chips get hotter - suffice to say that as temp goes up, resistance goes down so current go's up causing temp to go up so resistance goes down - ad naseum until either temp stabilizes or chip fries. Pesky laws of physics again. Do like PC's do. Mount cooling fans to flow air over chips. Consider Pelzior effect cooling chips - I use them on Cyrix 686-166 chips in mini-towers. Makes cold directly from current. Available from many sources. But the best cure is to condition the signals and mount the box inside. Believe me, the control electronics for jet engines aren't bolted to the afterburner. Cold temperatures specs relate more to physical properties rather than electronic. Storing cold like South Dakota blizzard and bringing gently to human temperature (like in passenger compartment) is not generally harmful. Blowing 4 second pass's at 40 below may crack, shatter or otherwise physically destroy said chips. Nice side effect - the metal firewall between the engine and the control box's blocks many of the stray EM (radio frequency noise) currents that can really hose up CPU's and memory etc. - ----- Cut here - personal comment follows ----- Q: What's the difference between Jane Fonda and Bill Clinton? A: She had the balls to go to Viet Nam Robert Harris - ---------- > From: Al Grippo > To: diy_efi@xxx.edu > Subject: Chip operating temperatures > Date: Tuesday, September 24, 1996 6:59 PM > > IC chips for automotive use are generally specified as having operating > temperatures from -40 deg C to 125 or 150 deg C. The 68332 chips bought in the > group pcb buy were rated 0 deg C to 70 deg C (32 deg F to 158 deg F). I'm sure > these are ok for prototypes, but is anyone concerned about them lasting 50-100 > k miles in a real environment ? > > Most of the critical parts for the board which I have accumulated are in the > automotive temperature range, but I have not been able to get the 68332 or sram > chips in this range. I know the part numbers, but was told by several major > suppliers (newark, future, hallmark) that these industrial/ milspec chips are > not stock items and must be ordered in large quantities. The same applies to > sram (the highest industrial range here is -40 deg C to 70 deg C). Is anyone > interested in a group buy for these ? > > Al Grippo ------------------------------ From: "Robert Harris" Date: Tue, 24 Sep 1996 13:22:53 -0700 Subject: Re: Chip operating temperatures Before being over-concerned about the chip operating temp, I'd look at the PC board itself. These boards are nothing but thin etched metal overlaid on a fiber-glass like material with a lot of resin. Every temperature cycle dries out a little more resin. They get brittle with age. They crack with vibration. They stress with each cycle - the board grows and shrinks at a rate different than the metal traces. Think I'm kidding. A desk top pc generally lasts until the owner can't stand it anymore, while a laptop is generally a tosser at about 3 to 4 years. Laptops get real brittle, with hairline cracks that can't be found or fixed. Symptoms like random freeze ups etc. = bad board. Why - vibration - temperature cycles - pressure cycles - that the desktop living at human comfort temperatures and no motion stress does not see. If it was up to me (and most German, Japanese and American car manufactures seem to follow the practice) I'd mount the board where there was the least thermal and mechanical stress possible and minimize the problem. Just a thought. - ----- Cut here - personal comment follows ----- Q: What's the difference between Jane Fonda and Bill Clinton? A: She had the balls to go to Viet Nam Robert Harris ------------------------------ From: Johan Rodling Date: Tue, 24 Sep 1996 22:08:44 +0100 Subject: Re: D disease > From owner-diy_efi-outgoing@xxx.edu Sun Sep 22 19:57 GMT 1996 > Date: Sun, 22 Sep 1996 09:40:57 -0700 (PDT) > X-Sender: talltom@xxx.com > Mime-Version: 1.0 > To: diy_efi@xxx.edu > From: talltom > Subject: Re: D disease > > > Hey Rickydik - you out there? Drove the mbz around some tonight for the > first time. > Feels like this brain is programmed more toward stoichoimetric, ie big bog. > Do the > d-jetronic's have a eprom? Is it swapable? The original was a Bosch 0 280 > 002 013, > and the one I replaced it with is a 0 280 002 005. Any ideas? Being as this > rig is > puny engined anyhow I kneed whatever it can do, and jacking fuel pressure > will make > a pig of it AS far as I know the D-Jetronic is an analog MAP system built on transistors. Got one my self. It's primarly designed for 4- & 6- cylinders, but is also used on V12's with a booster amplifier for the injetors. It works in batch mode, so it fires a group three injectors three times (?) each cycle. Those two part num's that you got could be different sets for e.g. a 4-cyl & a 6-cyl engine, but I'm not sure. I sugest that you take a peak inside the box and for instance check how many transistors are mounted on the cooler. This might give a lead (the V12 type has no cooler). Good Luck :-) /JR Unix is simple, but it takes a genius to understand its simplicity. -DMR '74 Jaguar XJ5.3 L (V12) - ------------------------------------------------------ Johan Rodling Email: Johan.Rodling@xxx.SE JoRoTech HB Phone: +46 (0)18 36 90 91 Borje, Stromsborg Fax: +46 (0)18 36 91 02 S-755 92 Uppsala, Sweden Mobile: +46 (0)708 385 380 ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Tue, 24 Sep 1996 15:46:25 -0500 Subject: Re: Chip operating temperatures >At 12:15 PM 9/24/96 EDT, you wrote: > >>But what about temperatures below zero degrees? H [ snip ] >about... Most chips will work outside their temp range, but how well is >another story. Most analog parts simply wont meet published specs (but when >do they?) like offset, slew rate, etc. Most digital stuff still works, but Precisely, but lets understand: a digital part is just an analog circuit in saturation (unless you're talking ECL, in which case it's analog stuff that's NOT in saturation). So, the analog parameters that shift cause the degradation of the "digital" performance. [BTW I have done analog and digital design for a long time -- and I find that the parts most likely to be on the ragged edge of specs are the digital ones -- esp. from certain (smaller) mfgrs.] >the timing parameters must be relaxed. Every now and then you can find a >part that wont work in the cold, but often it can be replaced (w/ another >identical part). Often the automative and comercial temp ranges are the >same part, but one is tested and guaranteed to the more extreme temps. The >only real difference I can tell (from practical experience) is the >packaging. The Mil spec stuff is almost always ceramic which may take the >temp cycling better, but the comercial and auto stuff appear to be in the >same plastic package (hope it doesn't crack at low temp). Typically, have three temp / performance ranges: commercial, industrial, and military. Price increases exponentially. Military usually has best specs, most tolerance for supply voltage and temp variation, etc. Usually has better plating on pins and is in ceramic header since epoxy softens and melts at the upper end of the mil-spec temp range. Also, can get better moisture sealing with ceramic. [One of the failure modes is moisture drawn into a hot chip as it cools down -- most pronounced with the plastic packages.] If you'll look at the "storage" specs you'll see that they can all be stored at high temps -- so, it's the packaging and whether or not the device goes out of spec that determines its rating. At high temps, the carriers tend to migrate across the junctions producing *permanently* degraded performance. All the cold will do is *temporarily* push the operating region out of spec. -- make it not work right (i.e. you could be walking). Bottom line: heat destroys; cold just makes it not work -- just like the rest of the stuff in your car. > In a nutshell: If you derate the comercial parts they often work well >outside their spec temp range. >SMD > >Remember that your interior can get VERY hot (when your away w/ the windows >rolled up) so dont assume your EFI computer will never have to work at 140F+ >ambient if its in the passenger compartment (still want to be able to start >your car, right? ;) Be sure to have adequate heat sinking to the enclosure to get the heat out of its interior. > Oh, and the way to keep from replacing the radiator because you forgot to >add antifreeze is to use an air cooled engine;) (Im a 911 owner) ------------------------------ From: "Mike Fahrion" Date: Tue, 24 Sep 1996 16:01:28 +0000 Subject: Re: Chip operating temperatures > To paraphrase Stephen Dubovsky's comment: > > > In a nutshell: If you derate the comercial parts they often work well > > outside their spec temp range. > > The chips (usually) are physically the same. If there is are several > sets of parameters in the databook (comm, ind/auto, military) you can > usually just use the other set of numbers. > An additional factor to ease your mind. The parts will only have to operate in that extreme cold condition for a *very* short time. The power consumption of the parts will heat them very quickly relative to that low of an ambient temp. Obviously later the heat of the cabin will bring them up to a comfortable temp. To take it one step further, it isn't terribly difficult to add a heater circuit that will turn on power to a several watt resistor when the ambient is below a certain threshold temp. Almost always, this is the most practical way to extend operation of a circuit into frigid temps due to the (sometimes) availability problems of wide temp parts. - -mike mfahrion@xxx.com ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Tue, 24 Sep 1996 16:25:09 -0500 Subject: Re: Chip operating temperatures >>From many years experience in the aerospace industry >operating temperatures are much more important than >storage temps. Mounting the components within the >passenger compartment will keep commercial quality >components well within specs regardless of outside temp. > >The mil-spec components price will shock your shorts off- Yep >so remember the big difference at high temps is the heat >dissipation capabilities of the chips. Think not? the parameters of the chip itself change with delta-T, so the chips are spec'd within certain limits. As I said in another post, the next biggie after what the manufacturer guarantees the chip to do is the physical limitation of package (epoxy vs. ceramic). Epoxy gets soft and melts / burns. It also allows moisture to creep into the chip. So, the same chip *might* function at high temp were it put into a better header -- then again, it might not, as the mfgr selects the better chips to charge more money for them! >I know >many PC's that people paid top dollar for are running pushed >processors (lower speed rated chips operated at higher >clock speeds) with a big fan glued to the chip. Yep, the heat in a digital circuit is mostly generated during the rise and fall time -- not while its HI or LO, so slower chips, pushed to faster PRR (i.e. clock period), will get hotter, as the transitions are occuring more often per unit of time. Therefore a heat sink is necessary. >Built a few >myself (with the customer knowing it). I could go into why >hot chips get hotter - suffice to say that as temp goes up, >resistance goes down so current go's up causing temp to go >up so resistance goes down - ad naseum until either temp Depends on whether we're talking about bipolar transistors for field effect transistors. Bipolars experience what is called *thermal runaway* due to their Beta increasing with temperature. In FET's, a drop in resistance actually produces lower heat dissipation, since P=EI and lower R means lower E dropped across the switch. When selecting an FET switch, one of the major parameters is lowest R(on). What we perceive as a high temp actually means a *real* hot spot(s) inside on the chip. At temps over something like 175 C or 200 C or so, migration of carriers begins and the switching speeds begin to deteriorate (permanently), causing more heating -- and on and on. >stabilizes or chip fries. Pesky laws of physics again. > >Do like PC's do. Mount cooling fans to flow air over chips. >Consider Pelzior effect cooling chips - I use them on Cyrix 686-166 >chips in mini-towers. Makes cold directly from current. Available >from many sources. But the best cure is to condition the signals Can mount metal tabs from the main heat generating sources to the enclosure (or mount them directly on the enclosure) with fins on the outside to help remove heat -- should be adequate for any condition you're willing to live in. [ snip sommore ] ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Tue, 24 Sep 1996 18:58:42 -0500 Subject: Re: Chip operating temperatures Oh me, PCB's are *extremely* durable! You can often bend one almost double without causing any damage. Hair line cracks are usually caused in the manufacture process due to a slight imperfection in either the mask (negative or positive) or the resist. 1/16" epoxy-glass boards are made from (typically) four layers of fine fiberglass cloth impregnated with epoxy resin. They last for many years -- there's stuff out there that's been working everyday for over twenty years!!! The major problem in circuit board failure (and this is an industry statistic) is solder joints. The major cause of problems in circuits overall is connectors. The rule of thumb is solder it rather than use a connector (includes IC sockets) unless it has to be removable. It is not true that the boards dry out or get brittle -- not epoxy glass. Phenolic starts out brittle (that's what you typically get if you buy from Radio Shack!) and is a very poor substrate (that's what you call the stuff under the copper foil the traces are made from). The wiring in car dashes is usually a flexible PCB made from a mylar film with the copper foil on it. It is true that problems can be created by the way components are mounted on the PCB. For example, GE made a two-way radio still used in many police, taxi, and other commercial apps called a Master-II. The audio board is surrounded by a casting and is about 5" square (been several years since I've been into one). The push-pull audio output stage was two TO-220 transistors (much like the transistors used to pulse injectors in EFI circuits) which were soldered to the board and bolted to the casting for heat dissipation. A common occurence was intermittent or failed audio due to the leads pulling away from the transistor's chip inside its header. See, the board was firmly mounted and the transistor was also, being bolted down, so as it heated and cooled there was no room for expansion/contraction eventually causing failure. This problem was easily fixed by putting a little "jog" in the transistor's leads so it could move a teensy bit. (Yes, "teensy" *IS* a technical term!) I used to work with shake tables big enough to put a refrigerator on. We simulated the vibes from rocket engines. At resonance, it's really neat to see stuff fly apart -- but PCB's weren't the problem. Everything else was. The case, the mountings, the connectors. Any large items on the PCB are also at risk -- e.g. relays, transformers, pots, switches, etc. The PCB itself is purty damm tuff!! So: (in the order I think most important, i.e. it's debatable) - - Protect your components from temperature extremes. Put heatsinks on things that get hot, but remember, that if the heat goes into a closed box, it will just heat everything else up, and the heatsink cannot work very well in a closed space. Try to get the heat outside, if at all possible, by providing aluminum or copper (low thermal resistance) paths directly from the part to the case. Your enclosure should be aluminum. Don't use steel or plastic as the heat can't get out. - - Protect your circuit from dirt and humidity. Digital circuits aren't too sensitive to current leakage due to moisture / dirt combo but your sensors are analog and Hi-Z. That means they are seriously affected by even slight moisture or dirt. (Frankly, I'm amazed the EGO works as well as it does, since its connector is near a serious heat source and is exposed to lots of dirt and water.) It's not a bad idea to coat the PCB. A solder mask is a real help in preventing humidity problems (on the other hand, it can be a real PITA if a break should occur in a trace somewhere). - - Protect it from undue vibration (don't put heavy things on the PCB, or if you must, be sure the board is supported near them). - - Dont put stress on connectors. Keep them away from dirt and liquids (water, oil, grease, battery acid, etc.) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - >Before being over-concerned about the chip operating temp, >I'd look at the PC board itself. These boards are nothing but >thin etched metal overlaid on a fiber-glass like material with >a lot of resin. Every temperature cycle dries out a little more >resin. They get brittle with age. They crack with vibration. They >stress with each cycle - the board grows and shrinks at a rate >different than the metal traces. Think I'm kidding. A desk top >pc generally lasts until the owner can't stand it anymore, while >a laptop is generally a tosser at about 3 to 4 years. Laptops >get real brittle, with hairline cracks that can't be found or fixed. >Symptoms like random freeze ups etc. = bad board. Why - >vibration - temperature cycles - pressure cycles - that the >desktop living at human comfort temperatures and no motion >stress does not see. > >If it was up to me (and most German, Japanese and American car >manufactures seem to follow the practice) I'd mount the board >where there was the least thermal and mechanical stress possible >and minimize the problem. Just a thought. > ------------------------------ From: Donald Whisnant Date: Tue, 24 Sep 1996 23:59:50 -0500 Subject: Re: 6811 Disassembler >From: Michael Haas[SMTP:Jemikhaas@xxx.com] >Sent: Saturday, September 21, 1996 1:37 AM >To: diy_efi@xxx.edu >Subject: 6811 Disassembler > >Hi, > > Could you send me a Copy of your 68HC11 Disassembler using Base 64. > > Thank You Very Much > > Michael J. Haas > Michael... I tried to email you a copy, but the message bounced back to me with an "unknown host" error... Email me private with your correct email address and I'll try again... Donald Whisnant dewhisna@xxx.com ------------------------------ From: RABBITT_Andrew@xxx.au Date: Wed, 25 Sep 1996 15:19:18 est Subject: Re: water/temp/mileage >the only time in the life of the car I ever saw this, and the only >thing changed before or after was the weather. And the gas pump/petrol bowser or whatever you guys call it. :) ------------------------------ End of DIY_EFI Digest V1 #286 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. A non-digest (direct mail) version of this list is also available; to subscribe to that instead, replace "diy_efi-digest" in the command above with "diy_efi".