Today's Message Index:
----------------------
1. 05:12 AM - Re: Re: Hobbs wiring (Ron Burnett)
2. 05:30 AM - Re: Re: Hobbs wiring (Kelly McMullen)
3. 06:41 AM - Re: Hobbs wiring (user9253)
4. 07:33 AM - Re: Re: Hobbs wiring (Alec Myers)
5. 09:10 AM - Re: Re: Hobbs wiring (Robert L. Nuckolls, III)
6. 09:16 AM - Re: Re: Hobbs wiring (Robert L. Nuckolls, III)
7. 02:14 PM - Re: Re: Hobbs wiring (Ron Burnett)
Message 1
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| Subject: | Re: Hobbs wiring |
Joe,
Don't have picture so will try to describe. I have converted from a Subaru back
to a Lycoming, so I have a keyed master switch and EFII ignition. The whole
system comes alive with the key, but has a switch that bypasses all if necessary.
Trying to tie in a Hobbs bought and in panel but never hooked up before. Now I
have the oil pressure activated switch teed into the VDO oil pressure sender
for the GRT EIS.
Thanks,
Ron Burnett
May you have the Lord's blessings today!
Sent from my iPad
> On Mar 9, 2017, at 7:55 AM, user9253 <fransew@gmail.com> wrote:
>
>
> You are on the right track if my interpretation of your post is correct. But
I can not say for sure until seeing a complete schematic of your proposed circuit
including the master switch and battery contactor. A picture is worth a
thousand words.
>
> --------
> Joe Gores
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=467106#467106
>
>
>
>
>
>
>
>
>
Message 2
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| Subject: | Re: Hobbs wiring |
What might be the advantage of a hobbs in a plane that cannot be used
for hire? Just curious.
Seems like tach would be more than sufficient.
A hobbs will accelerate when maintenance is required, make the aircraft
look higher time than it really is, etc. Not to mention the extra
complexity and potential failure points.
Certainly your choice to do if you want one.
On 3/11/2017 6:09 AM, Ron Burnett wrote:
>
> Joe,
>
> Don't have picture so will try to describe. I have converted from a Subaru back
to a Lycoming, so I have a keyed master switch and EFII ignition. The whole
system comes alive with the key, but has a switch that bypasses all if necessary.
>
> Trying to tie in a Hobbs bought and in panel but never hooked up before. Now
I have the oil pressure activated switch teed into the VDO oil pressure sender
for the GRT EIS.
>
> Thanks,
>
> Ron Burnett
Message 3
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| Subject: | Re: Hobbs wiring |
Ron,
It doesn't matter where the 12 volt supply comes from as long as it goes on and
off with the battery contactor. Just connect 12 volts to the hobbs meter and
to the indicator light as pictured in your original post. This advice is based
on the assumption that the switch in your picture is an oil pressure switch.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=467166#467166
Message 4
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| Subject: | Re: Hobbs wiring |
Most TC aircraft Hobbes meters don't get switched via the battery master. Too easy
to hide time by flying with the master off.
> On Mar 11, 2017, at 9:39 AM, user9253 <fransew@gmail.com> wrote:
>
>
> Ron,
> It doesn't matter where the 12 volt supply comes from as long as it goes on and
off with the battery contactor. Just connect 12 volts to the hobbs meter and
to the indicator light as pictured in your original post. This advice is based
on the assumption that the switch in your picture is an oil pressure switch.
>
> --------
> Joe Gores
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=467166#467166
>
>
>
>
>
>
>
>
>
Message 5
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| Subject: | Re: Hobbs wiring |
At 09:31 AM 3/11/2017, you wrote:
>
>Most TC aircraft Hobbes meters don't get switched via the battery
>master. Too easy to hide time by flying with the master off.
Correct. Most folks are unaware of the fact that
tens of thousands of Cessnas had an always hot
battery bus right at the battery contactor. It
feed two fuses . . . one for the Hobbs meter controlled
through an oil pressure switch . . . the other for
the electric clock.
If one would like to add a low oil pressure warning
light, then the hobbs feeder needs to drive from
a controlled source. In OBAM aircraft a good alternative
feed is the e-bus.
Now the low oil pressure light (and perhaps warning buzzer)
serves four functions. It monitors oil pressure, it controls
the Hobbs meter to measure ENGINE RUN time, it gives warning
at shut down that both the DC master and E-Bus alternate
feed switches are open.
See . . .
http://tinyurl.com/zlpjzuc
If you have an engine fitted with a PM alternator
(a la Rotax or SD-8 standby) one COULD fabricate a
circuit to watch for the existence of AC voltage
on the alternator winding and use this signal to
control the Hobbs and offer warnings for DC power
shutdown . . . you just wouldn't have oil pressure
warning.
Bob . . .
Message 6
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| Subject: | Re: Hobbs wiring |
At 11:07 AM 3/11/2017, you wrote:
>At 09:31 AM 3/11/2017, you wrote:
>>
>>Most TC aircraft Hobbes meters don't get switched via the battery
>>master. Too easy to hide time by flying with the master off.
>
> Correct. Most folks are unaware of the fact that
> tens of thousands of Cessnas had an always hot
> battery bus right at the battery contactor. It
> feed two fuses . . . one for the Hobbs meter controlled
> through an oil pressure switch . . . the other for
> the electric clock
Hmmm . . . not always two fuses . . . seems the 1976
C-172 drove the Hobbs and clock from the same fuse
Emacs!
Bob . . .
Message 7
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| Subject: | Re: Hobbs wiring |
My only tach is provided by the EIS.
I do not have an engine tach.
Thanks.
Ron Burnett
May you have the Lord's blessings today!
Sent from my iPad
> On Mar 11, 2017, at 7:28 AM, Kelly McMullen <kellym@aviating.com> wrote:
>
>
> What might be the advantage of a hobbs in a plane that cannot be used for hire?
Just curious.
> Seems like tach would be more than sufficient.
> A hobbs will accelerate when maintenance is required, make the aircraft look
higher time than it really is, etc. Not to mention the extra complexity and potential
failure points.
> Certainly your choice to do if you want one.
>
>> On 3/11/2017 6:09 AM, Ron Burnett wrote:
>>
>> Joe,
>>
>> Don't have picture so will try to describe. I have converted from a Subaru
back to a Lycoming, so I have a keyed master switch and EFII ignition. The whole
system comes alive with the key, but has a switch that bypasses all if necessary.
>>
>> Trying to tie in a Hobbs bought and in panel but never hooked up before. Now
I have the oil pressure activated switch teed into the VDO oil pressure sender
for the GRT EIS.
>>
>> Thanks,
>>
>> Ron Burnett
>
>
>
>
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