Today's Message Index:
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1. 06:35 AM - Re: Starter Solenoid Diode (user9253)
2. 07:20 AM - Re: Re: Starter Solenoid Diode (William Hunter)
3. 07:57 AM - Re: Starter Solenoid Diode (user9253)
4. 08:21 AM - Re: Re: Starter Solenoid Diode (William Hunter)
5. 08:38 AM - Re: Starter Solenoid Diode (Robert L. Nuckolls, III)
6. 08:47 AM - Re: Starter Solenoid Diode (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: Starter Solenoid Diode |
I had the same concerns as Charlie but did not say anything because I was not sure.
After sleeping on it, connecting an inductive load (starter) in parallel
with a Dynon input might not be a good idea. I suggest that input be used instead
for the Air filter door position sensor.
That diode will NOT protect the Dynon input from an inductive voltage spike.
Notice that the diode and Dynon input combination are connected in parallel with
the inductor (starter). And the banded end of the diode is connected to positive.
That is the same orientation as arc suppression diodes. Therefore the
diode will conduct inductive spikes right through the Dynon input. The Dynon
manual states, "The voltage on the general purpose inputs must not exceed 15
volts." I would call Dynon support before connecting an inductive load in parallel
with an input.
If Dynon gives the OK, would the circuit actually work? I assume the Dynon input
supplies 5 volts through a pull-up resistor. The input will be normally
grounded through the starter motor. When the contactor is energized, Dynon input
current will stop flowing because the load (starter) will draw current from
the highest voltage source which is the aircraft battery. The Dynon input will
then go high from the 5 volt pull-up resistor.
Like I said, I am not sure. I will not be insulted if someone corrects me.
Opposing views encouraged.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=471472#471472
Message 2
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| Subject: | Re: Starter Solenoid Diode |
Joe and Charlie,
As always I am VERY GRATEFUL for your time and help!!! I will call Dynon
today as soon as they open.
As Joe recommends, I might just eliminate the "I" post input to the Dynon
and roll (err...fly) with a simple LED next to the starter pushbutton.
As Joe was hitting send I was studying the AeroElectric diagrams.
Regardless of what I do with the "I" post, I still need an external diode on
my Ford starter solenoid.
I assume that the external diode needs to run from the "S" pole to the
solenoid case ground (a composite airplane) with the banded end closest to
the "S" pole as shown in the attached schematic). Can you PLEASE look it
over and make sure I got it right.
> I assume the Dynon input supplies 5 volts through a pull-up resistor.
This whole "Pull Up" resistor thing is confusing. The sensor inputs of the
Dynon EMS show 5 VDC. Here is a quote from the Dynon Tech Support on one of
the threads " The pin is pulled up internally to 5V. This means it's 5V when
nothing is connected and some path to ground is needed to reduce the voltage
below 5V. So you get 5V when nothing is connected and 0V when you connect
the wire to ground. This isn't "magic," it's just a 10K resistor to 5V."
..
THANKS AGAIN!!!
Bill Hunter
Message 3
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| Subject: | Re: Starter Solenoid Diode |
Bill, yes the diode is connected correctly. It is directly across the coil with
the banded end on the positive side.
About pull-up resistors:
The only way that an input can tell if a switch is open or closed is by sending
a small current through the switch. Current flows when the switch is closed
and current stops when the switch is open. The current must be limited to protect
the 5 volt source and to protect the wires. A 10K series resistor limits
the current. That resistor is called a pull-up resistor.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=471475#471475
Message 4
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| Subject: | Re: Starter Solenoid Diode |
Thanks Joe!!!
Very clear explanation...You would make an excellent electronics
instructor!!!
Thankfully there is still a Radio Shack in town...limited components but I
hope they will have the Dye-Oh-doe I need.
..
Cheers!!!
Bill Hunter
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of user9253
Sent: Thursday, August 3, 2017 7:57 AM
Subject: AeroElectric-List: Re: Starter Solenoid Diode
Bill, yes the diode is connected correctly. It is directly across the coil
with the banded end on the positive side.
About pull-up resistors:
The only way that an input can tell if a switch is open or closed is by
sending a small current through the switch. Current flows when the switch
is closed and current stops when the switch is open. The current must be
limited to protect the 5 volt source and to protect the wires. A 10K series
resistor limits the current. That resistor is called a pull-up resistor.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=471475#471475
Message 5
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| Subject: | Re: Starter Solenoid Diode |
At 09:07 PM 8/2/2017, you wrote:
>
>
>My Spanish uncle would call it a =93Dye-Oh-Doe=94
>and I know I need one however I do not know what value nor where to install
it.
>
>I want an indicator on my EMS to monitor the
>starter motor being energized and a cyber friend
>recommended installing a 1N4004 diode on my =93I=94
>pole of my starter solenoid to protect the Dynon
>EMS sensor and he drew up the attached PDF
>diagram and I will certainly do as he recommends.
>
>The additional question is=85can someone also
>provide me with a quick schmatic of what diode I
>should use and where and what polarity to
>install it to protect from electrical spikes (in
>the same manner as one does for master contactors)?
>
>..
>
>THANKS GUYS=85I am making progress this week (for a change)!!!
>
>Bill Hunter
Can't imagine why . . . if your EMS has inputs designed to
attach to any source of power on the airplane for the purposes
of monitoring (voltmeter input) then just tie it to the "I"
terminal directly. The diode as he as shown it would actually
prevent the EMS from seeing voltage on the "I" terminal.
Bob . . .
Message 6
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| Subject: | Re: Starter Solenoid Diode |
At 10:38 AM 8/3/2017, you wrote:
>At 09:07 PM 8/2/2017, you wrote:
>>
>>
>>My Spanish uncle would call it a =93Dye-Oh-Doe=94
>>and I know I need one however I do not know what value nor where to
install it.
>>
>>I want an indicator on my EMS to monitor the
>>starter motor being energized and a cyber
>>friend recommended installing a 1N4004 diode on
>>my =93I=94 pole of my starter solenoid to protect
>>the Dynon EMS sensor and he drew up the
>>attached PDF diagram and I will certainly do as he recommends.
>>
>>The additional question is=85can someone also
>>provide me with a quick schmatic of what diode
>>I should use and where and what polarity to
>>install it to protect from electrical spikes
>>(in the same manner as one does for master contactors)?
>>
>>..
>>
>>THANKS GUYS=85I am making progress this week (for a change)!!!
>>
>>Bill Hunter
>
> Can't imagine why . . . if your EMS has inputs designed to
> attach to any source of power on the airplane for the purposes
> of monitoring (voltmeter input) then just tie it to the "I"
> terminal directly. The diode as he as shown it would actually
> prevent the EMS from seeing voltage on the "I" terminal.
Oh, okay. If the input port to the Dynon is NORMALLY
looking for a 0-5v signal, then yes . . . as Joe
has pointed out, a pull-up resistor on the Dynon side
of the diode is needed to raise the input to approx 5v
when the "I" terminal RISES ABOVE 5v (starter getting power
from battery).
If, in this case, the EMS input is tailored to 0-5v
sensor inputs, then it may NOT be protected internally
for general used looked at voltages elsewhere on the
system. Do check with Dynon as to absolute maximums
that the input will tolerate.
Bob . . .
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