On Sun, 10 May 2015 12:29:20 -0700 (PDT), Lasse Langwadt Christensen Gave us:
Nope... the arcing always occurs. The cap was to balance it such that there was no molecular transfer, the most common source of point degradation in a coil/points system.
Removing the battery connection while the alternator is running can deliver up to 400V, but my alternator regulator designs had to pass that requirement even though it might kill the technician doing the dumb stunt ;-)
Protecting the regulator turned out to be relatively easy... you put the field driver device into BVcex, when A+ exceeds 18V. ...Jim Thompson
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I love to cook with wine. Sometimes I even put it in the food.
Pretty much everything Detroit made before the early 90s or so would disagree with you. The standard setup was at least a pair of 1156 or
1157 lamps (2.1 A on the bright filament), and sometimes two pairs. Starting about 1985 a third brake light got added to the load.I agree that relays can produce large spikes. I had a relay blow up a microcontroller input once. I sat down with a gel-cell, a relay, and an oscilloscope... getting 90 V out of a 12 V nominal circuit was educational. (Learn by destroying!)
I don't know how common relays in brake light circuits are, though. I know that even in older pickup trucks and vans, if you had the trailer package, there was a relay with the coil across the brake light switch and the contacts feeding the trailer connector.
Japan started using relays for other lighting circuits when the headlight switch moved to the steering column; I don't think they had room to run the heavy-gauge wires they needed into the column.
I have never seen one like this. Doesn't mean they don't exist, though.
Trivia: A relative has a 2006 Chevy Malibu, and recently took it in for three different recalls. One involves the wiring harness under the dash coming apart and keeping the brake lights from working. I was testing it out after the work and discovered that on that car, the brake lights don't work unless the key is on. I also discovered that it apparently doesn't use a brake light *switch*; rather it has a brake *position sensor* that feeds the body control module; the BCM then turns on the brake lights. There is a calibration procedure for the brake pedal position sensor. I'm speechless.
My portable NiMH battery charger, which probably has the most onboard computers of any car I've ever owned, just has a plain old switch for the brake lights. It feeds 2x 7443 and 1x 168 (or W5W), about 3.6 A total.
Thanks for the references. I have a personal project coming up that will involve designing a power supply that sometimes gets plugged into a car. The output requirements should be fairly modest (a watt or two of 3.3 V), but I want the input to not die when presented with this kind of stuff.
Standard disclaimers apply: I don't get money or other consideration from any companies mentioned.
Matt Roberds
And the car is iron.
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Welcome to my world.
My father's 1985 Cadillac something had a resistor and cazapitor in series across the brake switch. I don't recall if it was stock or if it was added by his mechanic. I'll be visiting an auto repair shop today, where I can ask.
My guess(tm) is that it's part of an ABS (Autie-lock Braking System) that needs to know how much effort the driver is putting into stopping the vehicle. Measuring the brake fluid pressure will not do because the ABS system will modulate the pressure to suppress the skid. I've never destroyed, err.... worked on an ABS system, so I'm not sure.
Most of my auto electric system experience is from installing 2way radios and computah based entertainment systems in cars. Protection from glitches is a must. At a minimum, a power zener, fuse, and BFC (big fat cazapitor). You might be interested in some of the projects: I'm currently accumulating the necessary parts and courage to install a computah in my 2001 Subaru Forester.
I used to have a routed wooden sign in my office. "Bribes graciously accepted". In 9 years at the company, all I received was a coffee cup coaster from a vendor that I detested. Perhaps your approach might be more effective.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Dude, you are replying to the wrong post...
Which they do. Is Google broken or something? Here, let me Google that for you :
Oh, good grief! Just because it's an "automotive part" doesn't mean it'll withstand a load dump (or other crap on the power bus) by itself. It won't.
For example, the LM2936 has an abs-max ("Input Voltage (survival)") of
60V. A load dump can easily be 150V. Fail!
Yes, yes, but if you actually go and read the specs, there are plenty that handle load dump and high voltage transients. A couple more search terms led me to several that are fully rated for use without the need for additional protections. Goodness, dude.
I'm sure that sensor does also feed into the ABS, but I'm not sure why. The two other cars I either own or drive (an '01 Toyota and an '00 Honda) can operate their ABS with just the input from the brake light switch, plus the usual wheel speed sensors. I'm pretty sure the ABS in the '96 Suzuki I used to wrench on also just used the brake light switch and wheel speed sensors.
I remembered after I wrote the above that the Malibu is really an Opel Vectra with Chevy stickers on it, so I blame the Germans. The pessimistic view is that German engineers don't know when to stop adding things to the design. The optimistic (?) view is that the German engineers assume that 1) the rest of the world has a vo-tech school system like Germany's, so that competent mechanics will be plentiful and
2) the rest of the world has a working economy, so car owners will be prepared to pay for stealership service. Neither of those conditions apply in the US, so the designs run into difficulties.At one unnamed company I worked for, we got official training on price- fixing, bribery, etc. What I took away from it was that in the US, Western Europe, and Commonwealth, the company didn't want you to pay bribes to anybody. In countries where you *have* to bribe people to get anything done, we were supposed to hire a "local agent" and not ask too many questions.
Matt Roberds
Yep, that's about it. Ethics are quite different in different parts of the planet.
[Q] What's the difference between a bribe and a commission? [A] A bribe is paid in advance. A commission afterwards. Otherwise, they're identical.In the enlightened western nations, accepting a bribe is considered a crime, while a commission is perfectly legal. Obviously, timing is important. However, in other nations, the use of a middleman in transactions has necessitated that their payment be made in advance as the parties involved could easily disappear, leaving the middleman without payment. This payment is seen as a bribe by westerners, but as a means of protecting their investment in the transaction by others. Western businessmen have not failed to notice how this works resulting in some aberrations, such as "points" in a loan, which is essentially the banks profit in advance. I won't pass judgment on either bribes or commissions, but I hope this explains how it works.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
That company you worked for must have a small market share over here ...
Good idea.
I personally am totally 100% corrupt. Just bring it on. :-)
Since the U.S. government has turned anti-corruption legislation into a lucrative profit center that's a very dangerous position for a company to aspire to.
Merely having an agent 'forget' the keys to a new Landrover on the desk of the son of a civil servant has cost many millions of dollars.
The former head of an big insurance company with a large (JV) market share in a rather corrupt country (India) swore that he'd never paid a bribe and that once people figured out that was the policy *and* they could make good money by following it the demands stopped. I'm inclined to believe him, but mostly because he's a native born Anglo Canadian.
-- Best regards, Spehro Pefhany Amazon link for AoE 3rd Edition: http://tinyurl.com/ntrpwu8 Microchip link for 2015 Masters in Phoenix: http://tinyurl.com/l7g2k48
On a sunny day (Tue, 26 May 2015 08:25:22 -0400) it happened Spehro Pefhany wrote in :
Yea well, 100 $ and I will say you are right. For 199 $ I say it twice
Maybe it is how the bribe is payed, for example politicians get rewarded with better positions and positive media when singing the song of the big cooperations. Journalist the same. Writers, anyone having influence on a large audience. And 'salary', you work for a bribe .. And peace, you are bribed not to start a revolution (for example negotiations with the unions) . Money makes the world go round, trust me.
So in a way, the system camouflages the bribes, those still exist. The system will not tolerate anything or anyone bypassing its own ways.
I was reading here ? a while back: "Do not steal, the government does not want competition.." So in simpler societies the camouflage of bribing has not advanced that much, and it is more obvious to some.
What has it to do with 'tronics? I dunno, needed a break from math and programming.
Our system will eventually get so hypocrite that is must collapse. For normal human nature to have its ways...
Ergo "load dump"....
Try the excavating company that used a DC welder to jump a dead
24V tri-axle dump truck. The 120 watt RCA 31 MHz mobile was NFG after.We pulled it and when I opened the final amp cover, the 3 stud mount "helicopter" transistors fell out, at least the top halves of each.
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Things like that happen for many other reasons.... Load dumping is a vary specific case. I am not saying that isn't what happened however, when connecting external sources to trucks for a jump start, way too many times have I seen such actions done with the ground of the jump source connected to the chassis while the high side connected to the battery post of near by.. That can cause a doubling of voltage if devices are not using their own ground lead to the battery along with the high side. Even then you have a chance of getting that extra voltage through other means like the coax being chassis grounded at some end point. There are reasons why many use a dual power feed from sensitive equipment all the way to the power source and shields are connected only at one end etc..
It's just something to think about ..
Jamie
A friend, a retired warrant officer, had a variation.
[Q] What's the difference between a Warrant Officer and a commissioned one? [A] A warranty is a written guarantee of performance. A commission is the payoff for a good sales job.-- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close.......................... Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433
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