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what's the condenser for on a mechanical voltage regulator?



 
 
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  #1  
Old February 19th 07, 02:02 AM posted to rec.autos.tech
[email protected]
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Posts: 38
Default what's the condenser for on a mechanical voltage regulator?

Just tried my '66 GTO's mechanical voltage regulator on my friend's
'69 Firebird and it started charging his battery again. Even though
he had bought a new voltage regulator a month or so ago. (And then an
alternator.) His does not have the condenser installed on the voltage
regulator like mine does, but there's a terminal for it.

I'm wondering if the condenser is necessary, maybe to keep the
contacts from burning? I'd heard it was to prevent radio
intereference, which we don't care about. I can't find anything in
the service manual about it. If it's necessary to prevent contacts
burning, maybe his new voltage regulator fried its contacts.

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  #2  
Old February 19th 07, 11:55 AM posted to rec.autos.tech
Ted Mittelstaedt
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Posts: 696
Default what's the condenser for on a mechanical voltage regulator?


> wrote in message
oups.com...
> Just tried my '66 GTO's mechanical voltage regulator on my friend's
> '69 Firebird and it started charging his battery again. Even though
> he had bought a new voltage regulator a month or so ago. (And then an
> alternator.) His does not have the condenser installed on the voltage
> regulator like mine does, but there's a terminal for it.
>
> I'm wondering if the condenser is necessary, maybe to keep the
> contacts from burning? I'd heard it was to prevent radio
> intereference, which we don't care about. I can't find anything in
> the service manual about it. If it's necessary to prevent contacts
> burning, maybe his new voltage regulator fried its contacts.
>


The condensor keeps the points from burning up. When the points break,
for a short time, current keeps flowing in the condensor. So, the points
don't arc. Then when the contacts close the condensor dumps it's
charge across the closed points and is then ready to absorb the current
from the next break.

Ted


  #3  
Old February 19th 07, 01:04 PM posted to rec.autos.tech
Hustlin' Hank
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Posts: 8
Default what's the condenser for on a mechanical voltage regulator?

On Feb 18, 8:02�pm, wrote:
> Just tried my '66 GTO's mechanical voltage regulator on my friend's
> '69 Firebird and it started charging his battery again. *Even though
> he had bought a new voltage regulator a month or so ago. *(And then an
> alternator.) *His does not have the condenser installed on the voltage
> regulator like mine does, but there's a terminal for it.
>
> I'm wondering if the condenser is necessary, maybe to keep the
> contacts from burning? *I'd heard it was to prevent radio
> intereference, which we don't care about. *I can't find anything in
> the service manual about it. *If it's necessary to prevent contacts
> burning, maybe his new voltage regulator fried its contacts.


I could be wrong, but I always thought they were for radio noise only
since most don't have them. The points on the voltage regulator
solenoids don't open and close at over 1000 times per minute like the
igniton points (only when key is turned on/off), therefore they won't
burnt out nearly as quick.

Hank

  #6  
Old February 19th 07, 04:29 PM posted to rec.autos.tech
Mike Romain
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Posts: 3,758
Default what's the condenser for on a mechanical voltage regulator?

The points 'do' arc out and burn in those regulators or you wouldn't
need new ones.... I was always under the impression you needed the
condenser to slow this down.

Sometimes if they have arced while closed, you can thump on the
regulator to get it going again if I remember right. The bad alternator
might have caused this also. Some others you could open and inspect.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
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wrote:
> Just tried my '66 GTO's mechanical voltage regulator on my friend's
> '69 Firebird and it started charging his battery again. Even though
> he had bought a new voltage regulator a month or so ago. (And then an
> alternator.) His does not have the condenser installed on the voltage
> regulator like mine does, but there's a terminal for it.
>
> I'm wondering if the condenser is necessary, maybe to keep the
> contacts from burning? I'd heard it was to prevent radio
> intereference, which we don't care about. I can't find anything in
> the service manual about it. If it's necessary to prevent contacts
> burning, maybe his new voltage regulator fried its contacts.
>

  #7  
Old February 19th 07, 07:43 PM posted to rec.autos.tech
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Posts: n/a
Default what's the condenser for on a mechanical voltage regulator?


"Mike Romain" > wrote in message
g.com...
> The points 'do' arc out and burn in those regulators or you wouldn't
> need new ones.... I was always under the impression you needed the
> condenser to slow this down.


You're right, Mike. The condensor is there to stop RFI but it does it by
stopping the sparking, which is an interrupted DC. Just like the condensor
used to do on points, it provides a low impedance path for high frequency
AC or interrupted DC.

While an electromechanical regulator might not be a critical to spark damage
as ignition points were, the principle is similar.



  #8  
Old February 19th 07, 09:16 PM posted to rec.autos.tech
[email protected]
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Posts: 166
Default what's the condenser for on a mechanical voltage regulator?

On Feb 19, 5:04 am, "Hustlin' Hank" > wrote:

>
> I could be wrong, but I always thought they were for radio noise only
> since most don't have them. The points on the voltage regulator
> solenoids don't open and close at over 1000 times per minute like the
> igniton points (only when key is turned on/off), therefore they won't
> burnt out nearly as quick.
>
> Hank


Those points DO open and close thousands of times per minute. They
are buzzing constantly, making and breaking contact and forming a
(more or less) square-wave input to the alternator rotor. The
induction of the rotor's coil smooths out the wave somewhat, but also
causes sparking at the regulator points and they will ultimately
either burn out or weld themselves shut. Filing them doesn't help
much; they are silver-faced and once the silver is gone they quickly
fail again.
There is a resistor across the contact points. You'll find it
under the regulator frame, in open air. When the points open, the
current takes the path through the resistor, reducing the current flow
to the rotor and thus reducing the alternator output voltage. If the
voltage gets really high, the regulator's moving contact goes to
ground and takes the rotor current to zero.
The capacitor will reduce radio noise and contact point
erosion, though many regulators will go for years without a capacitor.
The rotor's induction isn't all that great and the resistor absorbs
much of the peaking created by the rotor coil.
After my students wire up the alternator charging systems on
the teaching boards, we can see the constant, tiny spark between the
points if the room is really dark. Those points are moving constantly.
They have to, to keep the voltage exactly where the regulator wants
it. The electronic regulator makes much more sense, modulating the
current instead of repeatedly interrupting it altogether.
I have schematics here of the electromechanical regulator. I
can't find a similar one on the 'net.

Dan

  #9  
Old February 19th 07, 09:25 PM posted to rec.autos.tech
Bob Flumere
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Posts: 23
Default what's the condenser for on a mechanical voltage regulator?

On Mon, 19 Feb 2007 12:43:05 -0600, > wrote:

>
>"Mike Romain" > wrote in message
ng.com...
>> The points 'do' arc out and burn in those regulators or you wouldn't
>> need new ones.... I was always under the impression you needed the
>> condenser to slow this down.

>
>You're right, Mike. The condensor is there to stop RFI but it does it by
>stopping the sparking, which is an interrupted DC. Just like the condensor
>used to do on points, it provides a low impedance path for high frequency
>AC or interrupted DC.
>
>While an electromechanical regulator might not be a critical to spark damage
>as ignition points were, the principle is similar.
>

To the OP.. you do NOT need this cap.....
It is NOT a functional part of the charging system in any way...
It is only a high frequency bypass to ground for radio noise
suppression.

Its purpose and connection into the circuit in this application does
not affect nor control the arcing at the voltage control contacts...

Having this cap in the circuit (or not) will not damage the regulator
or affect the charging system in any way.

The capacitor on the GM Delco voltage regulator is ONLY for RFI
suppression.. it is not in the "Field" circuit where the altenator
field (rotor) contacts are located.

In the days of generator (as opposed to "alternator" charging systems,
mis-connecting the RFI capacitor to the field terminal of the
generator (an easy mistake to make in the day) would CAUSE a failure
of the voltage control contacts in the regulator!!
The cap in this particular application was mounted on the generator
case, and designed to be connected to the generator "Armature"
terminal which was in fact the current output terminal.

GM DELCO used to put a big round red cardboard warning tag on the
"field" terminal of the generators telling you NOT to connect the
capacitor wire to this (field) terminal!
In this instance, the capacitor was being used to suppress the RFI
from the arcing at the generator brushes which would be heard as a
"whine" on an AM radio..

Of course these two connection terminals were located side by side on
the generator case, and only a few of us could read the big red tag.
So when this mistake was made the voltage regulator failure would
occur within a couple hundred miles. <BG>

These uses are NOT related to the use of a capacitor in "Point +
Condenser ignition system, where the cap serves an entirely
different function in the creation of the High Voltage spark and
in fact does absorb the arc at the contacts that is created
by the collapse of the field in the primary of the ignition coil on
the "break" of the contacts.

Again, I repeat, this capacitor on the Delco Altenator regulator base
is NOT involved in the charging circuit in any way, and only exists to
suppress the RFI generated by the arcing at the vr contacts...
If you look at the back of the regulator base, you will see that the
capacitor terminal is merely an extension of the "B" or Battery
terminal lug. The capacitor from there to ground suppresses any
HF RFI that might be generated from reaching the rest of the car's
electrical system and thence being heard as a "popping" type of
static on an AM radio..

Feel free to ask for more technical explanation an any time.
School is out fo now .. there will be a quiz later <G>



Bob F.
 




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