Today's Message Index:
----------------------
1. 11:50 AM - Fw: AC voltage at aircraft bus at approx. 1000rpm (teamgrumman@aol.com)
2. 02:48 PM - Re: Fw: AC voltage at aircraft bus at approx. 1000rpm (FLYaDIVE)
3. 07:56 PM - Re: Fw: AC voltage at aircraft bus at approx. 1000rpm (teamgrumman@AOL.COM)
4. 08:50 PM - Re: Fw: AC voltage at aircraft bus at approx. 1000rpm (Gil Alexander)
5. 09:56 PM - Anouncement (923te)
Message 1
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| Subject: | Fwd: AC voltage at aircraft bus at approx. 1000rpm |
Here is the ripple on a PP alternator. Even with a Zeftronics regulator
and a Garmin audio panel, the noise comes through.
-----Original Message-----
From: Keith Wannamaker <keith@wannamaker.org>
Sent: Thu, Feb 4, 2010 10:51 am
Subject: Fwd: AC voltage at aircraft bus at approx. 1000rpm
Gary, here is an oscope on my bus with the plane-power. I'm a bit like a
hog looking at a wristwatch with the readout. I'm not sure if it is sayi
ng 1/2 volt AC top to bottom or 1/8 volt top to bottom. The plane power
guy claims that 1/8 volt ac is within spec, but I sent him the picture an
d am waiting to hear back.
Keith
Message 2
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| Subject: | Re: Fwd: AC voltage at aircraft bus at approx. 1000rpm |
Keith & Gary:
Looking at your picture ... In the lower right corner the screen reads 0.2
V/Div.
That means between EACH large Tic it is 0.2 V.
SO ... Your Peak reading is about (again looking at the picture) 0.24 Volts
and the Peak to Peak (P-P) is 0.28 Volts.
As for what is acceptable... That may be determined by the manufacture or
the FAA. I do not know. BUT! When I do a very simple but ACCURATE test
using a DMM (Digital Multi Meter) I look for 0.4 to 0.5 V AC at the BATTERY
to determine if a diode is bad.
For the little voltage you are seeing I would put a 0.001 uF Ceramic Cap in
parallel with a 50,000 uF (or more) Electrolytic Cap and the NEG side of the
Cap goes to GROUND, POS side to POS Battery
AND/OR - Put a large electrolytic Cap from the 'S' terminal of the VR to
Ground.
If you have that little noise (0.48 V P-P) the caps will remove it.
Barry
On Thu, Feb 4, 2010 at 2:48 PM, <teamgrumman@aol.com> wrote:
> Here is the ripple on a PP alternator. Even with a Zeftronics regulator
> and a Garmin audio panel, the noise comes through.
>
>
> -----Original Message-----
> From: Keith Wannamaker <keith@wannamaker.org>
> To: Gary Vogt <teamgrumman@aol.com>
> Sent: Thu, Feb 4, 2010 10:51 am
> Subject: Fwd: AC voltage at aircraft bus at approx. 1000rpm
>
> Gary, here is an oscope on my bus with the plane-power. I'm a bit like a
> hog looking at a wristwatch with the readout. I'm not sure if it is saying
> 1/2 volt AC top to bottom or 1/8 volt top to bottom. The plane power guy
> claims that 1/8 volt ac is within spec, but I sent him the picture and am
> waiting to hear back.
>
> Keith
>
>
Message 3
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| Subject: | Re: Fwd: AC voltage at aircraft bus at approx. 1000rpm |
The whole point is not to patch together something that should work withou
t a "FIX." It says right on the alternator and the associated paperwork
that no noise filter is required.
It's kind of like wearing a glove when you buy a pen that leaks.
-----Original Message-----
From: FLYaDIVE <flyadive@gmail.com>
Sent: Thu, Feb 4, 2010 2:47 pm
Subject: Re: TeamGrumman-List: Fwd: AC voltage at aircraft bus at approx.
1000rpm
Keith & Gary:
Looking at your picture ... In the lower right corner the screen reads 0.2
V/Div.
That means between EACH large Tic it is 0.2 V.
SO ... Your Peak reading is about (again looking at the picture) 0.24 Volt
s and the Peak to Peak (P-P) is 0.28 Volts.
As for what is acceptable... That may be determined by the manufacture or
the FAA. I do not know. BUT! When I do a very simple but ACCURATE test
using a DMM (Digital Multi Meter) I look for 0.4 to 0.5 V AC at the BATTE
RY to determine if a diode is bad.
For the little voltage you are seeing I would put a 0.001 uF Ceramic Cap
in parallel with a 50,000 uF (or more) Electrolytic Cap and the NEG side
of the Cap goes to GROUND, POS side to POS Battery
AND/OR - Put a large electrolytic Cap from the 'S' terminal of the VR to
Ground.
If you have that little noise (0.48 V P-P) the caps will remove it.
Barry
On Thu, Feb 4, 2010 at 2:48 PM, <teamgrumman@aol.com> wrote:
Here is the ripple on a PP alternator. Even with a Zeftronics regulator
and a Garmin audio panel, the noise comes through.
-----Original Message-----
From: Keith Wannamaker <keith@wannamaker.org>
Sent: Thu, Feb 4, 2010 10:51 am
Subject: Fwd: AC voltage at aircraft bus at approx. 1000rpm
Gary, here is an oscope on my bus with the plane-power. I'm a bit like a
hog looking at a wristwatch with the readout. I'm not sure if it is sayi
ng 1/2 volt AC top to bottom or 1/8 volt top to bottom. The plane power
guy claims that 1/8 volt ac is within spec, but I sent him the picture an
d am waiting to hear back.
Keith
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Message 4
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| Subject: | Re: Fwd: AC voltage at aircraft bus at approx. 1000rpm |
Gary,
At 5 mS/div on the scope... could you be seeing some 60 Hz pickup? -
which would be just over 3 divisions.
Is the noise frequency proportional to RPM?
How long was the ground lead to your probe?
gil A
At 08:55 PM 2/4/2010, teamgrumman@aol.com wrote:
>The whole point is not to patch together something that should work
>without a "FIX." It says right on the alternator and the associated
>paperwork that no noise filter is required.
>
>It's kind of like wearing a glove when you buy a pen that leaks.
>
>
>-----Original Message-----
>From: FLYaDIVE <flyadive@gmail.com>
>To: teamgrumman-list@matronics.com
>Sent: Thu, Feb 4, 2010 2:47 pm
>Subject: Re: TeamGrumman-List: Fwd: AC voltage at aircraft bus at
>approx. 1000rpm
>
>Keith & Gary:
>
>Looking at your picture ... In the lower right corner the screen
>reads 0.2 V/Div.
>That means between EACH large Tic it is 0.2 V.
>SO ... Your Peak reading is about (again looking at the picture)
>0.24 Volts and the Peak to Peak (P-P) is 0.28 Volts.
>As for what is acceptable... That may be determined by the
>manufacture or the FAA. I do not know. BUT! When I do a very
>simple but ACCURATE test using a DMM (Digital Multi Meter) I look
>for 0.4 to 0.5 V AC at the BATTERY to determine if a diode is bad.
>
>For the little voltage you are seeing I would put a 0.001 uF Ceramic
>Cap in parallel with a 50,000 uF (or more) Electrolytic Cap and the
>NEG side of the Cap goes to GROUND, POS side to POS Battery
>
>AND/OR - Put a large electrolytic Cap from the 'S' terminal of the
>VR to Ground.
>
>If you have that little noise (0.48 V P-P) the caps will remove it.
>
>Barry
>
>
>On Thu, Feb 4, 2010 at 2:48 PM,
><<mailto:teamgrumman@aol.com>teamgrumman@aol.com> wrote:
>Here is the ripple on a PP alternator. Even with a Zeftronics
>regulator and a Garmin audio panel, the noise comes through.
>
>
>-----Original Message-----
>From: Keith Wannamaker <<mailto:keith@wannamaker.org>keith@wannamaker.org>
>To: Gary Vogt <<mailto:teamgrumman@aol.com>teamgrumman@aol.com>
>Sent: Thu, Feb 4, 2010 10:51 am
>Subject: Fwd: AC voltage at aircraft bus at approx. 1000rpm
>
>Gary, here is an oscope on my bus with the plane-power. I'm a bit
>like a hog looking at a wristwatch with the readout. I'm not sure
>if it is saying 1/2 volt AC top to bottom or 1/8 volt top to
>bottom. The plane power guy claims that 1/8 volt ac is within spec,
>but I sent him the picture and am waiting to hear back.
>
>Keith
>
>
>===================================
>ator?TeamGrumman-List">http://www.matronics.com/Navigator?TeamGrumman-List
>===================================
>ttp://forums.matronics.com
>===================================
>ibution">http://www.matronics.com/contribution
>===================================
>
>
Message 5
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