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Old 05-30-2013, 04:46 PM
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Default Briggs Charging System Mod?

I have your standard Briggs Dual Circuit alternator on the MULE. Two outputs off the alternator. One remains AC for lighting, one gets clipped to DC with a diode for charging. What if-

I were to ditch the diode, and run both circuits through the inputs of a bridge rectifier? Would I not then double my DC current availability? Are the two circuits in phase with each other, and if not, will it create a problem? Are there any other foreseeable issues with the idea? Thanks!
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Old 05-30-2013, 06:19 PM
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Quote:
Originally Posted by toystory_4wd View Post
I have your standard Briggs Dual Circuit alternator on the MULE. Two outputs off the alternator. One remains AC for lighting, one gets clipped to DC with a diode for charging. What if-

I were to ditch the diode, and run both circuits through the inputs of a bridge rectifier? Would I not then double my DC current availability? Are the two circuits in phase with each other, and if not, will it create a problem? Are there any other foreseeable issues with the idea? Thanks!
OK; here I go, sticking my head out to get it chopped off........

I'm totally clueless on what the spec's are for this charging system; all I can do is try to explain how a standard automotive alternator generates DC power....

1] A DC generator is basically a universal motor used in reverse (being driven by the engine); the polarity is straight- either positive or negative. Voltage regulation is usually handled by a separate voltage regulator.

2] An alternator is basically a multi phase AC motor being driven in reverse (like the generator listed above); for it to generate DC current (no matter what the voltage) takes some additional work. Now, for the record, an alternator generates sine wave power; to generate a direct current output, it uses a bridge type rectifier to cut off one half of the sinusoidal current from each leg of the windings; the "DC" current that we measure and use from an alternator comes from the peak of all those sine waves. If you were to look at it's output on an oscilloscope, you would see all of the peak voltage points for the individual windings on 1/2 of the wave cycle all overlapping, thus generating synthetic "DC" current.

I wish I had the classroom visuals that I had in college; when you see the breakdown on the scope, it really starts to make sense......

Hope this helps...Pat
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Old 05-30-2013, 06:35 PM
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Gotcha on all that, but this system differs somewhat. The DC circuit is achieved through a single diode, not a 4 diode bridge rectifier.

My biggest hurdle I figuring this stuff out, is understanding the source. I don't know whether its two different coil windings, whether they're in phase or out, and what would be the ramifications of tying them together with a bridge. In addition, that leaves me with an external ground from the bridge that I assume I would tie to the chassis. Making things more confusing is that I think one side of the alternator output is internally grounded...
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Old 05-30-2013, 06:44 PM
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Quote:
Originally Posted by toystory_4wd View Post
Gotcha on all that, but this system differs somewhat. The DC circuit is achieved through a single diode, not a 4 diode bridge rectifier.

My biggest hurdle I figuring this stuff out, is understanding the source. I don't know whether its two different coil windings, whether they're in phase or out, and what would be the ramifications of tying them together with a bridge. In addition, that leaves me with an external ground from the bridge that I assume I would tie to the chassis. Making things more confusing is that I think one side of the alternator output is internally grounded...
Times like this, I wish we were next door neighbors. I don't have all the fancy lab equipment from college, but I've got a hunch we could start to sort it out with the stash of multimeters I have here at home.....

Have you ever thought of relocating to the West Michigan area??????

Thought I'd ask..... Pat
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Old 05-30-2013, 08:03 PM
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Yeah- add my 3 DMM's and 2 AMM's to the mix... Michigan? No. But I've long toyed with the idea of taking up residence in a nice midwestern state, maybe even the south.
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Old 05-30-2013, 08:09 PM
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Quote:
Originally Posted by machinist@large View Post
I wish I had the classroom visuals that I had in college; when you see the breakdown on the scope, it really starts to make sense......

Hope this helps...Pat
You mean like these?


AC run through a half-wave rectifier



Graetz bridge rectifier: a full-wave rectifier using 4 diodes.



Full-wave rectifier using a center tap transformer and 2 diodes.


Like Pat said, rectifying AC results in pulsating DC. You can, however, add a smoothing resistor to the circuit to smooth out the jittery direct current and turn it into rippley current.

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Old 05-30-2013, 08:20 PM
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Yup, I have all that too (but thanks for the reinforcement info). As I said, the source(s) is a bit of a mystery to me, so I am unsure of potential results...
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Old 05-30-2013, 08:24 PM
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Quote:
Originally Posted by toystory_4wd View Post
Yeah- add my 3 DMM's and 2 AMM's to the mix... Michigan? No. But I've long toyed with the idea of taking up residence in a nice midwestern state, maybe even the south.
Virginia is a nice place (minus NoAV)

Quote:
Originally Posted by toystory_4wd View Post
Yup, I have all that too (but thanks for the reinforcement info). As I said, the source(s) is a bit of a mystery to me, so I am unsure of potential results...
I'd be pulling it apart to see
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Old 05-31-2013, 03:55 AM
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I wouldn't know what to look for! This goes a bit beyond my electrical knowledge. I have one (or 2) in my parts stash, so I don't even have to disassemble anything.
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Old 06-13-2013, 02:24 PM
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Quote:
Originally Posted by toystory_4wd View Post
I have your standard Briggs Dual Circuit alternator on the MULE. Two outputs off the alternator. One remains AC for lighting, one gets clipped to DC with a diode for charging. What if-

I were to ditch the diode, and run both circuits through the inputs of a bridge rectifier? Would I not then double my DC current availability? Are the two circuits in phase with each other, and if not, will it create a problem? Are there any other foreseeable issues with the idea? Thanks!
Assuming the alternator has two separate coils, the two would be out of phase... hook them up and you could get either constructive or destructive interference...

Why couldn't you just rectify the second AC output and then parallel them?
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Old 07-25-2013, 07:23 PM
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Quote:
Originally Posted by oscaryu1 View Post
Assuming the alternator has two separate coils, the two would be out of phase... hook them up and you could get either constructive or destructive interference...

Why couldn't you just rectify the second AC output and then parallel them?
That may be doable...

I may finally get some firm answers to this. Yesterday, I had a customer rather unexpectedly GIVE me an oscilloscope! Now, I haven't so much as laid a finger on one in the better part of 20 years, so I'm going to have to re-familiarize myself. Last night I did some reading and (re)learned how to get a calibration wave.

Once I've got a chance to play, I'll hook up to the MULE's alternator and see what it tells me.
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Old 07-25-2013, 07:34 PM
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Quote:
Originally Posted by toystory_4wd View Post
That may be doable...

I may finally get some firm answers to this. Yesterday, I had a customer rather unexpectedly GIVE me an oscilloscope! Now, I haven't so much as laid a finger on one in the better part of 20 years, so I'm going to have to re-familiarize myself. Last night I did some reading and (re)learned how to get a calibration wave.

Once I've got a chance to play, I'll hook up to the MULE's alternator and see what it tells me.


SCORE!!!!!

Treasures like this don't fall from the sky; they come from hard work and connections that appreciate the work that you do.....

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Old 07-25-2013, 07:42 PM
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I was grateful, to be sure- but indeed it fell from the sky. Well- working hard and having a good attitude towards the customer helped!

I was doing some flood-related demolition in a Toronto home over the last 2 days. I went into the customer's (80+ year old fellah) little hobby room and saw some electronics related stuff, including the oscilloscope. I asked him if he was an electronics technician, and we talked for a few minutes. Ultimately, he told me it worked and he hadn't touched it in years, so (without me asking) he offered that I take it if I could make use of it.

It's not a particularly freaky unit, but it will do the job! Below is a google-sourced pic of it.
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Old 07-25-2013, 08:03 PM
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Quote:
Originally Posted by toystory_4wd View Post
I was grateful, to be sure- but indeed it fell from the sky. Well- working hard and having a good attitude towards the customer helped!

I was doing some flood-related demolition in a Toronto home over the last 2 days. I went into the customer's (80+ year old fellah) little hobby room and saw some electronics related stuff, including the oscilloscope. I asked him if he was an electronics technician, and we talked for a few minutes. Ultimately, he told me it worked and he hadn't touched it in years, so (without me asking) he offered that I take it if I could make use of it.

It's not a particularly freaky unit, but it will do the job! Below is a google-sourced pic of it.


Nice!! While i don't have any electronic widgets that can even come close, I've scored some eclectic tooling of other sorts along the way, the 4'x6' cast iron welding table being one of them....

I really don't have any day to day need for an oscilloscope, other than I have an idea of what I could learn to do with one.... Maybe devino would relocate?????

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Old 07-25-2013, 09:09 PM
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Very nice score! I'm almost jealous! I've been wanting a 'scope.

Quote:
Originally Posted by machinist@large View Post


Nice!! While i don't have any electronic widgets that can even come close, I've scored some eclectic tooling of other sorts along the way, the 4'x6' cast iron welding table being one of them....

I really don't have any day to day need for an oscilloscope, other than I have an idea of what I could learn to do with one.... Maybe devino would relocate?????

I knew there was a reason I clicked on this thread! What's that now? Relocate?
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Old 07-26-2013, 04:27 AM
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I don't have a daily use for a 'scope either. Be nice to have now and then. Back in my playing days, I really thought it'd be cool to tune my guitar to one!
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Wrench, Wheel, Wreck, Repeat...
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