Wow, I feel like i just slept at a Holiday Inn last night.

That was very well written Brian, thanks for sharing. :thumbs:

Is Brian still selling these PWM's?
 

So, is Brian selling these things anymore? I've still got a MkVIII fan and serpentine setup to install and I, like DB, would like to have a variable speed control that works. If I get one, I think I'll wire it from the battery too.

Wow I just found this tread, I've been really busy and havn't had much Forum time :ack:

I love this kind of stuff. Automotive electrical is pretty easy compared to some things out there. Slow, Low and sloppy.

I must say that Baskin1 really sounds pretty pompus.
He has a known failure mode on a hot seller and his fix is to tell customers not to do that.

He tries to explain the issue by saying that the problem is a voltage current phase error in the charging circuit.
Then he sends us to a link on oscilliators???:rolleyes:

Hmm, OK, except that we are talking DC, which has a pretty dang long period ( like the life of the battery ) I don't care how the Alt creates the power, only what comes out of it. and that a 3 phase fully rectified DC signal.

Like this;
http://www.ibiblio.org/obp/electricC...Semi/03269.png

Now Baskin could try and make the argument that it's pulsed DC since the alt is rectified.
But then he says the battery filters it, and the 10ga wire acts as an inductor(of non trivial value I assume? Sure...)

So how can anyone make the argument that there is any phase error in a DC circuit with a large battery and a large gauge wire connection to the Charging system?

The boy is grasping at straws. I would have believed him if he said there are 1.5kv swithching spikes at the altenator that get attenuated closer to the battery to a tolerable level.

Or even that he doesn't really know why it happens but it does fail frequently when connected to the alt and rearely when connected to the Battery.
( Which is what I suspect it the truth, he doesn't really know)

But Phase errors in a DC curcuit???
Give me a break!
Keith

So you decided to :beatdeadhorse: :beatdeadhorse: :beatdeadhorse:

with YOUR version of Brian bashing horse pucky.

NICE.

carefull, he's gonna call you a pee pee whacker.:rofl:

Well this is fun thread:cool: To the poster that mentioned high freq as the reason speakers blow. The leading cause of voice coil failure is signal clipping....simply put: voice coils (and the amp that drives it) are designed to deliver (amp) and accept (voice coil) an AC waveform only. Clipping imposes DC on the coil, resulting in excessive heat being generated, and the resulting death of the voice coil.....sometimes with a nice small fire:eek: Leading reason this happens: underpowered amps being overdriven. Buy a big power amp, stick with 18db xovers and never look back!!!

That's pretty low. Me thinks you are well practiced in the art of putdowns.

Gotta love a good engineering discussion:D

How does a 18db crossover eliminate the DC component??

It does not stop clipping, but does limit the energy delivered to the speaker due to the sharp cutoff freq. Applying the freq range a speaker was designed to reproduce, and not feeding it "notes" above and below it's range, results in less or maybe even no overloading of the driver. I should not have mentioned "non clipping" related items in the same paragraph...beat this engineer:o :smash:

In all seriousness, this is a great thread. Learning how your equipment works make you a better operator!!!

OK thats what I thought.

HEHE....guys lets not confuse Brain Baskin with 3 color diagrams....

second off, any body wanna bet I can design a better controller???

but not VARIABLE speed,,.....lets just go for simplicity and CHEEPness..

how about something that does what 'they' claim for an aftermarket price of less than 100 bux or a junkyard price of 'FREE'>>>


Good old electronics, allways more and more for less and less.....

kinda makes me want to advizzzze my kids into that field.....NOT!!!!....

LOL, Gene, what are you going to invent for us? The Switch?:thumbs:

Naaa.....a solid state Rheostat.....

complete with pulse inverter and inverse logic, that inverse logique was a French invention....


:lol:

I could whip up a twin-relay on/off controller in about five minutes. That's not the point. The point is preventing the fan from hitting the electrical system with a 105A startup spike. That can't be terribly good for everything else.

All fine and dandy, I run a 17SI 108 amp alt with serp drive....it's larger diameter than the other SI series alts....came on a '79 Seville with r/wind defogger.....at any rate, it's a bolt in swap, and off that alt I wired a fuse link about 2" long and ~10 ga wire to the fan relay, which is hard on and hard off, was there that way for some 5 years running an '87 vette fan in stock '72 shroud....got rid of that when going to the dual spals running essentially the exact same wiring setup/relay...hard on/hard off, works fine....see a slight pull on the voltmeter when the fans come on for maybe 1/2 second or so...that's all....

NOW, I could put in another relay with a lower temp setting than the computer has, with a series resistor and let them fire up slower, but WHAT is the POINT????

Noise?? you exhaust is too quiet....I barely hear my fans....true my hearing is shot from too much loud stereo over the decades, that and the gun hobby too...:lol: :lol: :eek: :yesnod:

Actually they not significantly louder than many other cars/trucks.....

This controller has a soft start feature also:

http://store.summitracing.com/partde...5&autoview=sku

I didn't fire up my good OLD Tek scope yet, but you know, I going to just DO that, just did the DVM, turning on and off the a/c switch that of course turns on and off the fans, through the computer input to the fan relay....it's TPI controlled.....either way the alt was putting out 14.4 something, and everyone was happy, I hit the a/c switch and the DVM dipped to 13.4 something for an instant, then went back to 14.4 so everyone seemed happy.....I should look at the spike with differentiation input on the scope....but too lazy....

:lol:

Well, I got a little less lazy now, and dug out my old scope.....

on the a/c input, I see the 3 fuzzes all nice and neat, and so put trace on super slo.....at the power out stud, it dips damn close to 6 volts, down to 8.8 volts or so....maybe a schosch less on instant fans turn on.....whoopie doo, lasts about 200 ms......

in other words, NOT AN ISSUE.....

mrvette
you beat me to it. i was going to get my tek scope out (if i could find it). did you try to get a pulse on start-up? maybe sync it to the sense wire to hold the image on the first revolution of the alternator. i think that's were these voltage spikes are supposed to occur. if someone has a newer scope with a memory, the first few seconds could be captured.
jeff

You mean when starting the car engine??? engaging the starter??? NO....we all know it dips to about 10.5+++ volts, depending on bat condition...mine spins over immediately, even after sitting a week ....

wasn't particularly after images, just amplitudes....

200 ms/box sweep,,....so saw the dip and recovery....

of course withthe fans on the output was a bit more raggedy looking cause I was about 2 volts per box, seeing some ignition noise, and some slight trash when the fans were on, but with them off, the output was very smooth....but at any rate it seems less than a volt worth of trash under worst condiitons....maybe 1/2 a volt due to the 3 phase outputs....like I said...whoopie doo.....not an issue....