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Electronic geeks required

Old 01-10-2019, 08:21 PM
  #41  
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Originally Posted by mrvette View Post
Sorry Jeff, too damn cold here the last few daze, and other issues running wild....and having just put the 3rd alt in there, I let it fail first.....be a while, I hope.....I did use a CS144 on a camper I did some dozen years ago...feeding a marine deep cycle for the inverter, as well as the 24 series for starting....

but these daze my spine and other arthritic areas just slo my enthusiasm to nothing anymore...damnit....
Hey buddy. No hurry in this quest.
We just need volunteer #2.
Mike>? Do you have access to a scope?

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Old 01-10-2019, 11:38 PM
  #42  
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Originally Posted by Redvette2 View Post
Three….one to insist the schedule needs to be moved to the right,
one to complain that the budget is too tight,
and one to say it can’t be done.
Lol. I have experienced the last two in the past.
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Old 01-11-2019, 05:44 AM
  #43  
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I have this scope that plugs into my laptop. Ive only used it a few times but it seems to work. Measure the voltage ripple at alternator output and bat neg ?




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Old 01-11-2019, 08:58 AM
  #44  
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Originally Posted by Greengear View Post
I have this scope that plugs into my laptop. Ive only used it a few times but it seems to work. Measure the voltage ripple at alternator output and bat neg ?



Sure. See post #5. The more results we can have, the more conclusive.
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Old 01-11-2019, 11:22 AM
  #45  
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Here's my weapon of choice lately from EBAY for about $45. It's a DSO168 portable digital storage scope. 20Mhz bandwidth, no laptop required.



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Old 01-11-2019, 01:11 PM
  #46  
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The more data, the better. See what you can measure.
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Old 01-11-2019, 02:58 PM
  #47  
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Originally Posted by DblTrbl View Post
Here's my weapon of choice lately from EBAY for about $45. It's a DSO168 portable digital storage scope. 20Mhz bandwidth, no laptop required.


I looked at small hand held scopes too. I probably should have grabbed one of those instead of the laptop version.
I just got a dc clamp on amp meter. It was cool to see how many amps my c3 starter and headlights draw.
I have done quite a bit of automotive wiring repair over the years but I still dont use a scope much. Maybe making it easier to conmect would help.


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Old 01-11-2019, 06:58 PM
  #48  
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Ok, you made me curios so I checked my '71. When I converted to electric fans and EFI I swapped out the stock 10SI alt for a 12SI. It's an el cheapo Autozone rebuild, but it's been fine for years. With fans running half speed + stereo on (big Rockford Fosgate amp from the 90's) I got this:

Alternator stud: 0.18V
Battery: 0.016V (notice the extra zero in there)

Btw, no need for a scope to measure ripple. A good 'True RMS' volt meter is all you need. I use a Brymen BM829s.
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Old 01-11-2019, 09:27 PM
  #49  
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Originally Posted by zwede View Post
Ok, you made me curios so I checked my '71. When I converted to electric fans and EFI I swapped out the stock 10SI alt for a 12SI. It's an el cheapo Autozone rebuild, but it's been fine for years. With fans running half speed + stereo on (big Rockford Fosgate amp from the 90's) I got this:

Alternator stud: 0.18V
Battery: 0.016V (notice the extra zero in there)

Btw, no need for a scope to measure ripple. A good 'True RMS' volt meter is all you need. I use a Brymen BM829s.
Can you measure one more item? The starter post to battery negative.
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Old 01-11-2019, 09:35 PM
  #50  
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Too cold to crawl under the car and don't like doing that with it running. It will be close to the battery readings anyway.

And I don't think I can get to the starter post with my long tube headers without burning most of the skin off my hands. lol

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Old 01-11-2019, 09:39 PM
  #51  
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Originally Posted by zwede View Post
Too cold to crawl under the car and don't like doing that with it running. It will be close to the battery readings anyway.

And I don't think I can get to the starter post with my long tube headers without burning most of the skin off my hands. lol
Fair enough. Thank you for your efforts. It starts the baseline.
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Old 01-11-2019, 09:41 PM
  #52  
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Originally Posted by Big2Bird View Post
The more data, the better. See what you can measure.
You do know that meter data doesn't prove much without knowing the wiring configuration?
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Old 01-11-2019, 10:14 PM
  #53  
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Originally Posted by lionelhutz View Post
You do know that meter data doesn't prove much without knowing the wiring configuration?
True. The "assumption" is stock wiring. It might be prudent to key that into the quest.
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Old 01-11-2019, 11:22 PM
  #54  
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Totally stock wiring inmy car.
Here is my reading seems like 100hz ripple but I could be wrong.
Pic shows about 10 waves per 100ms division. Last pic shows how ripple stops but baseline voltage remains as soon as I turn off engine.
The thing that seems to potentially invalidate my test os that the scope shows 1.6v not 13-15v as I wouls expect. This could be because my probe has a 10x switch on the side.






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Old 01-11-2019, 11:24 PM
  #55  
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Originally Posted by Big2Bird View Post
Hey buddy. No hurry in this quest.
We just need volunteer #2.
Mike>? Do you have access to a scope?
Been watching this thread, but have been tied up with unexpected family stuff the past few weeks. Finally getting caught up. I've got a couple scopes that have been gathering dust lately, but I oughta be able to play around a little on this topic. The '69 is apart right now to take some more weight out of the car, but my "84 is running. I moved the battery in it to the rear compartment for better weight distribution, so it ends up electrically configured somewhat similar to a C3. I run small batteries in both cars for reduced weight, but I can probably scrounge/install a regular size battery too for a bit of comparison purposes.
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Old 01-11-2019, 11:48 PM
  #56  
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Originally Posted by Greengear View Post

Here is my reading seems like 100hz ripple but I could be wrong.
Back in the day...30 years ago when I worked for Kenwood- Car Audio- we did a lot of testing trying to solve the infamous "alternator whine."

On a brand new at the time 90 T-Bird SC - The frequency was in the couple hundred range @ 1800RPM. So 100Hz sounds correct at idle.


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Old 01-12-2019, 12:05 PM
  #57  
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Originally Posted by Greengear View Post
Here is my reading seems like 100hz ripple but I could be wrong.
The frequency will vary directly with the rpm if that actually is alternator ripple. So, try revving the engine and see what it does.
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Old 01-12-2019, 10:27 PM
  #58  
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Default Good read on the subject

The following article is a good reference for this discussion.

https://moretraction.com/2018/08/31/2416/

Last edited by Bullshark; 01-12-2019 at 10:34 PM.
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Old 01-12-2019, 10:45 PM
  #59  
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Originally Posted by Bullshark View Post
The following article is a good reference for this discussion.

https://moretraction.com/2018/08/31/2416/
Thanks BS.
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Old 01-12-2019, 10:47 PM
  #60  
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Originally Posted by Bullshark View Post
The following article is a good reference for this discussion.

https://moretraction.com/2018/08/31/2416/
Good article- can even download it in PDF

Sort of confirmed my dirty bus and the clean buss thoughts- AND the often debated large a$$ wire I run-

THANKS for posting it up!!!

BTW- I like this- have only see 1 post versions


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