Today's Message Index:
----------------------
1. 01:43 AM - Re: Re: flyback diode across fuel pump (Bob Verwey)
2. 06:03 AM - Re: flyback diode across fuel pump (user9253)
3. 06:18 AM - Re: Re: flyback diode across fuel pump (C&K)
4. 06:19 AM - Re: Re: flyback diode across fuel pump (Alec)
5. 06:39 AM - Re: Re: flyback diode across fuel pump (Charlie England)
6. 07:23 AM - Re: Re: flyback diode across fuel pump (Alec Myers)
7. 08:23 AM - Re: Re: flyback diode across fuel pump (Charlie England)
8. 11:40 AM - Re: flyback diode across fuel pump (Robert L. Nuckolls, III)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: flyback diode across fuel pump |
Why the cap Joe and not just a diode?
On 26 Aug 2022 17:20, "user9253" <fransew@gmail.com> wrote:
A diode won't hurt anything as long as the banded end is connected to
positive.
Van's RV-12 schematic shows an optional 22,000 microfarad capacitor
across the fuel pump.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=507781#507781
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: flyback diode across fuel pump |
> Why the cap Joe and not just a diode?
I don't know. Perhaps a capacitor helps to reduces interference to the aircraft
electrical system. Maybe Bob N will reply.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=507793#507793
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: flyback diode across fuel pump |
My thoughts are that a diode with a finite voltage drop does nothing for
quieting noise from the pump that is less than that finite voltage drop
(usually 0.6 volt for silicon diode). Comutated motors put some hash on
the supply line. I'm not aware of it typically causing problems but a
capacitor should help quiet such noise somewhat.
Ken
On 27-Aug.-22 9:03 a.m., user9253 wrote:
>
>
>> Why the cap Joe and not just a diode?
> I don't know. Perhaps a capacitor helps to reduces interference to the aircraft
electrical system. Maybe Bob N will reply.
>
> --------
> Joe Gores
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=507793#507793
>
>
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: flyback diode across fuel pump |
Used to be capacitors were cheaper than diodes, I think.
Sent from my iPhone
> On Aug 27, 2022, at 09:04, user9253 <fransew@gmail.com> wrote:
>
>
>
>> Why the cap Joe and not just a diode?
>
> I don't know. Perhaps a capacitor helps to reduces interference to the aircraft
electrical system. Maybe Bob N will reply.
>
> --------
> Joe Gores
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=507793#507793
>
>
>
>
>
>
>
>
>
Message 5
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: flyback diode across fuel pump |
Diodes used as arc suppressors are pennies each. They 'bleed off' the large
voltage spikes that happen when contacts open and load is suddenly removed
from a circuit.
Capacitors wired as power supply 'filters' typically exist to smooth
variations in DC levels. They store energy during low demand, and give it
up when demand causes voltage to sag below their charge state. Those
variations can come from the 'ripple' in rectified AC supply voltage, or
from variations in DC loads. The obvious example of (huge) variation in
load would be the starter, causing 'brownouts' of electronic devices, other
examples are inrush current to incandescent lamps, DC motors, or for a more
repetitive example, a Facet pulse pump (though I wouldn't have expected the
draw of a Facet pump to have a significant effect on DC bus stability).
Charlie
On Sat, Aug 27, 2022 at 8:22 AM Alec <alec@alecmyers.com> wrote:
>
> Used to be capacitors were cheaper than diodes, I think.
>
>
> Sent from my iPhone
>
> > On Aug 27, 2022, at 09:04, user9253 <fransew@gmail.com> wrote:
> >
mail.com>
> >
> >
> >> Why the cap Joe and not just a diode?
> >
> > I don't know. Perhaps a capacitor helps to reduces interference to the
> aircraft electrical system. Maybe Bob N will reply.
> >
> > --------
> > Joe Gores
> >
> >
> >
> >
> > Read this topic online here:
> >
> > http://forums.matronics.com/viewtopic.php?p=507793#507793
> >
> >
> >
> >
> >
> >
> >
> >
> >
>
>
===========
===========
===========
===========
===========
>
>
Message 6
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: flyback diode across fuel pump |
On Aug 27, 2022, at 9:38 AM, Charlie England <ceengland7@gmail.com> wrote:
>Diodes used as arc suppressors are pennies each.
They are, now.
Message 7
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: flyback diode across fuel pump |
On 8/27/2022 9:23 AM, Alec Myers wrote:
>
>
> On Aug 27, 2022, at 9:38 AM, Charlie England <ceengland7@gmail.com> wrote:
>
>> Diodes used as arc suppressors are pennies each.
> They are, now.
How far back do you want to go? I ran a computer repair business in the
1970s/80s/90s, and they were pennies each back then. Electrolytic caps
big enough to work as legit power supply filters were a lot more
expensive back then, too.
--
This email has been checked for viruses by Avast antivirus software.
www.avast.com
Message 8
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: flyback diode across fuel pump |
At 09:57 PM 8/25/2022, you wrote:
><john_s_bright@yahoo.com>
>
>Someone on VAF suggested putting a flyback suppression diode across
>fuel pump leads like we do with contactor and relay solenoid coils.
>This was re an automotive fuel pump like SDS/EFII/Airflow Performance/Walbro.
>
>What say Bob et Al?
Did the author cite a noise problem which was
mitigated by adding this component?
I'm mystified by any assertion of added value.
Rotary pumps powered by pm motors have no
'flyback' event. PutPut pumps like the
Facet devices have electronically driven
solenoids that 'cock' a compression spring.
A cruise through the genealogy of exemplar
patents for such pumps . . .
https://tinyurl.com/2e6mmzyr
. . . illustrates commonly applied
technology for mitigating flyback
energies in these devices that include
resistors, diodes and capacitors as
part of the designs dating back over
30 years.
I'm curious as to the history of
the thread.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|