Question For John G

MarcellOctober 30, 2005

I read your post on the battery charger. I remebeing scoping the alternator output on several vehicles a few years back, they all contained an Ac ripple in their voltage output. I am curious have the new alternators improved to a point where the produce pure dc or have the car makers started installing something to convert this voltage to pure dc?

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John G did provide a link to a good tutorial on alternators, if you haven't taken a look, I recommend you do.

    Bookmark   October 31, 2005 at 8:06AM
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Hi Marcell. Good to see you back around.

Some AC ripple, and other electrical noise is normal in every part of the charging circuit. Thats why it's necessary to be able to see it, measure it, and then determine if it's playing a role in the vehicles problem.

One such potential problem would be noise that gets passed to a computer communication line. If the noise is pulling the circuit one way, while a controller needs to move that voltage the other way in order to make a byte of information the other controllers on the circuit could miss that piece of information. Which of course brings us all the way back to the battery charger situation and doing computer flashing. Imagine trying to reprogram a module and then have voltage spikes corrupting the information.....

    Bookmark   October 31, 2005 at 8:26AM
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Thakns, for the answer John. I dug my old Heathkit scope out and tested the ouput from and old ATR charger I have. The spikes in the voltage output are quite high in amplitude and at real close intervals. I then checked the output from the alternator of a 05 Buick Lesabre. The spikes are much lower, less amplitutde and appear at much longer intervals. So I see what you mean, thanks for satisfying and old man,s curiosity. Marcel

    Bookmark   October 31, 2005 at 3:26PM
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Now how many people do you suppose remember Heathkit?
I still have a Heathkit vacuum tube color tv set. It has been sitting in a shed for at least 30 years, do you suppose the vacuum tubes may be worth something in, say, a museum?
I have several test bench electronic tools built from Eico kits, yes even an oscilloscope, it never worked well.

How long has Heathkit and Eico been out of business, I'd guess at least 30 years.

    Bookmark   October 31, 2005 at 9:25PM
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Jerry, Eico went before Heath, I think Eico about 75, Heath lasted into the 80,s. I built a heathkit color tv, Oscilloscope, vtvm signal tracer, tube tester, capacitance tester and an engine anaylyizer. I was a radio tech in the service, However I attended auto mechanics school went into auto repair and owned a garage many years . However I always daubled in electronics. The Heathkit tv you have will sell on Ebay as will any other of the Eico or Heath stuff. There are lots of collectors who have genuine interest and will pay very well for these things. Also if you have any of the manuals they are worth even more. A friend sold several Heathkit pieces on ebay and the prices he received were un believable. if you have any of these articles you want to get rid of Ebay is the place to do it.

    Bookmark   November 1, 2005 at 2:59AM
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Thanks for the possible way to get some final value out of my old equipment built as part of a hobby and career.

I was in the Naval Air, and Electricians Mate, was an AE2 P1 when I got off active duty and went into the reserves, I was a Chief Petty Office when I decided to get out of the reserves in 1968. I built Eico versions of all the instruments you mention, except the tube tester. That was on my list, I just didn't get to it before transistors took over. I went to college after leaving the Navy and have worked as an electrical engineer for many years - as could be concluded from the date I put on myself above, not to mention the date of the subject of this excursion away from the subject of this CAR forum thread.

I have all the manuals to go with the test and signal generation equipment. As I mention the scope didn't work well, the problem there was a poor quality (multi-output) transformer, which had to supply the hight voltages associated with vacuum tubes. A few years back I purchased a dual trace scope from Radio Shack. It is a fully calibrated (time base and amplitude) with multiple trigger capabilities. It looks and functions like the old Tectronics (sp?) and HP scopes I used in my early days as an engineer. I think I paid about $300 for it, I couldn't pass up the buy. I rarely use it, but enjoy seeing it on my electronic/computer workbench anyway. This bench still has projects on it, that I never seem to find time to get around too... could be I'm spending too much time chatting on these forums.

    Bookmark   November 1, 2005 at 8:55AM
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If you have no scope, you can use a regular (cheap) telephone to listen to the AC ripple from the alternator.

I used a telephone to diagnose a bad filter capacitor in a power supply.

The amount of AC ripple is directly proportional to the volume of hum you get out of the earpiece.

    Bookmark   November 1, 2005 at 4:40PM
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Good suggestion Brian. Jerry my email addy is email me and we can talk without tying up space on the forum Marcell

    Bookmark   November 1, 2005 at 8:19PM
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