X-Junk-Score: 0 [] X-Cloudmark-Score: 0 [] X-Cloudmark-Analysis: v=2.3 cv=PbaBeRpd c=1 sm=1 tr=0 a=rNh5z51zqBKAkJEDufJaSw==:117 a=y4yBn9ojGxQA:10 a=8IjSFGYmQxEA:10 a=r77TgQKjGQsHNAKrUKIA:9 a=pGLkceISAAAA:8 a=Ia-xEzejAAAA:8 a=o1OHuDzbAAAA:8 a=D2BJnjrTAAAA:8 a=_6GpL_ENAAAA:8 a=7g1VtSJxAAAA:8 a=5w2CahdAZyDHLTkjq9gA:9 a=QEXdDO2ut3YA:10 a=Qa1je4BO31QA:10 a=gvSQh4r-fQ0A:10 a=4PR2P7QzAAAA:8 a=8Ve2g95sPOO5RvU-:21 a=_W_S_7VecoQA:10 a=Urk15JJjZg1Xo0ryW_k8:22 a=5YQ6H4ZxyGn-KoBYtt8s:22 a=gS_LDhYnuIKGLnqJNh-5:22 a=grOzbf7U_OpcSX4AJOnl:22 a=4dqwQCo7Po2mVW515mGf:22 From: "Finn Lassen finn.lassen@verizon.net" Received: from sonic313-56.consmr.mail.ne1.yahoo.com ([66.163.185.31] verified) by logan.com (CommuniGate Pro SMTP 6.2.14) with ESMTPS id 618570 for flyrotary@lancaironline.net; Sat, 08 Aug 2020 10:05:30 -0400 Received-SPF: pass receiver=logan.com; client-ip=66.163.185.31; envelope-from=finn.lassen@verizon.net DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=verizon.net; s=a2048; t=1596895512; bh=rhChIiyThE3q6MJa8Ut3rzlcA1A/kQEmYOLaAq0M91o=; h=Subject:To:References:From:Date:In-Reply-To:From:Subject; b=IjeVgQCidoIuvndCRQa3kALK3fU16V5ok095YeRvUwngfBjY0Kajx++dJC0H7VFxY2caE8PMCi03CMOkbxDQnLqgNs2UZVxTi8Lkv9lKxxQ+cT/LvojQqEXtBumfn598WZrk3oKisftrzZbaVBoLGYVt1C+f0emanv5G22FL1hHfLSIfK1nMhNuAGniH8whQB76IgPWwBzIoE4ZVGJjaE5yPjCMb4wC4jP/CD79Q9VdSY4STnwPYLMRuxWW61FEXleS/mI2WOBSNkbzIBIhFYn9A5qQDOqTCsej9eGTAnyIRS/rAUhK9xE5BsPs0hgV4ILsUxLYP75KkKiucOfUL9Q== X-YMail-OSG: PfgvJMoVM1lvUmpASSB2S_ZErAhQmo.GMeljbDlleootkyjOmgxV3BM9hSKfzoJ P.xjyt_0wpPy0eUM7XC9CsnAAgbLCMoHaMNaQ4BI4qY.v11sjA_l9PHVZgnWWh8rWpjyg.H0jkeK 95tt_2Z85sI1BUjaBJZPIWU.z0PpORIVaQNoteBbxsGWDOOrt0WKDfRGc1yP4ZTAyifid5rSEKPE 0SRV6YfEEefRO4tEhsV.G84f1cI3t.djqEizi5vT0oUp0hrnpfvUcp0lNc8h5A9l_GUuxoZhV26_ U_.GEHbi3W8NSaNzxZCXg.tBSm0FjKDrZJbhX7UMoR.jThJrO2i7OPIfiflnm4fug.zeTXMF_nEk ZMDjsgwdylgu5BoW.qmDxCf.k.EBEPnt3YfpNMPS8si.R.EbVcW3u1j.gmTt_Xu5.e2S7sDjco3f kKaVl3.EkNdSyNgyLYREG3wznvoy87IIaThNCdmcM0JB4_QjkaW6J1sEY5dEixTXNE0DEa3zI0s2 A53wlRmGhDC9wWwzlRu2ftOw6cFcKdjHd1lSUuTEPD0auO0Rded10P5j7fCuS.rGCfkJymtsN7nj 1OXGpQfwA95hxSuo1toGZPfiLTZcUgJ3BFcSKAfPg8EYoBevycg9gS2S2IL20vgd0zmYQwsHF4wA MNpPD7H9WIg8e7RqW5JwtbOOhYyxoJ1WKKVdfg28BegC70iuKJbB04kTl_cEtrTgTmypaxRhu2RM E6ZxLwyroESmb0K_4uY01gqp8UPR0hNcg3MXBY6j.MSjM4GnMJ1_.7KMXWRAAHvbRYkYuJpwP0ih POerkcm2CRG1YXSO8oYI91TTYuqnI3hQaHYgm1MCJ5I19KbOUc0ON9mN10Ti68P.OS9aE3kGCDtU VAwXaGaSffUeUSJsAZ9aiEaGJNfismzjGfNLzqE85S0tR9y7PwERb0LvhllgbngKHNPZYV3sWJKN ErmlXOmN6ie7N2Xd1PPVwnhSkwW0g_sJcCKIdJvnf98MLt6HSQwgsmDI9t54JaD.U2buQeT2thKY nM8ZVZMYh3DGfLVp1OWCqNxlWupaYun.HX644J4LQm.UQVNtV96M_Vtl_X4wTp9kEak4gCa_di1H NvPSFPWU.xMQYD.6kl8G2xLOYWSaZMHN7dlVANTBY7FHm0LcTU1sApO6IqTAYhl6gVBBhljMu8lb MT9RK8YDOtCpvs30bwdCUFnUDCVo7TqiSK4C_4TBq_SXnmuRjI88c.Lzuw0wAq_0OlwbhqTXg4vc sMExUWZhxNPwetZ80wQyWJ2oBdrfkknQtMs71FLz5bcGHTm5Q31oUMF25gnDAdPDmJLv0kJ_vm.D gBoOfkfsilZi0fVxJuc8sKt5_1_57qE.zPxfR4x7n9ssWV8wNqmqXA.J43OtTl1q_X8kT1av4b3u bGQcCRHB_MYVGBlo6GLE55P6d4sdtpVGHctBhI753PSXeYU3wHbmvP2yA5peXQoUw Received: from sonic.gate.mail.ne1.yahoo.com by sonic313.consmr.mail.ne1.yahoo.com with HTTP; Sat, 8 Aug 2020 14:05:12 +0000 Received: by smtp423.mail.bf1.yahoo.com (VZM Hermes SMTP Server) with ESMTPA ID 00e2ebd82f4a08b6cb68181cb757a19a; Sat, 08 Aug 2020 14:05:09 +0000 (UTC) Subject: Re: [FlyRotary] Re: Dyno Sheet To: Rotary motors in aircraft References: Message-ID: <68ccdb8e-5ca5-aa6f-8399-56f25b72ea41@verizon.net> Date: Sat, 8 Aug 2020 10:05:05 -0400 User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/alternative; boundary="------------C137CE3ED7C93B17A2B027B0" Content-Language: en-US X-Antivirus: Avast (VPS 200808-2, 08/08/2020), Outbound message X-Antivirus-Status: Clean X-Mailer: WebService/1.1.16436 mail.backend.jedi.jws.acl:role.jedi.acl.token.atz.jws.hermes.aol Apache-HttpAsyncClient/4.1.4 (Java/11.0.7) Content-Length: 18079 This is a multi-part message in MIME format. --------------C137CE3ED7C93B17A2B027B0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit If max from the pressure sensors is 35mV it should work very well directly with the EGT inputs. Yes, brilliant. If 1.45psi is 35mV then the Skyview should show something like 850C before you change the Skyview default EGT setting for an EGT channel. (41uV/C) Just be aware that the temperature around the Skyview /may/ influence the numbers. But if you're only interested in the differences between the 5 sensors and not the absolute numbers from flight to flight, it may not be a factor. A temperature probe on the Skyview, logged to one of the channels, should let you correct the EGT-Pressure channel values in the spreadsheet for zero-offset. Actually if the difference in Skyview ambient temperature is only 10 to 20C, it may prove insignificant (0.41 to 0.82mV compared to the 35mV). In other words, an 8C difference in ambient temperature should only give a 1% offset error in your pressure readings. Don't know if you can even calibrate the EGT-Pressure inputs with a manometer that accurately. Finn On 8/7/2020 9:50 PM, Stephen Izett stephen.izett@gmail.com wrote: > So Finn. The fuller story is. > > I???m thinking I need to make up a string of 5 amps for my 5 transducers that I have already, to condition the few millivolts to 0-3.3v for a pic micro or the sort. > Then I???m thinking how do I read and log the data. > But I???d like it synced with the dynon log data which is brilliant. > Look at a graph with pressures along side temps and speeds and altitudes???.. > > And then I think of the abundant excess EGT inputs that are used to that kind of millivolt input all connected and logged and displayable. Just a bit of configuration and basically no circuit and development time required. > > Is it to good to be true. Maybe, but indications are its too easy. > > Brilliant if it works. > > Steve > > > > > > >> On 8 Aug 2020, at 9:39 am, Stephen Izett stephen.izett@gmail.com wrote: >> >> Hi Finn >> I input a polynomial based on the raw data from the transducer data sheet. >> Full scale output is 35mV for 1.45psi. >> Offset at 0 reading is on average 20mV. >> >> But I thought I???d create a polynomial based on a new set of data using the water manometer incase the 'junction flux capacitor' was throwing out the readings to far. >> To far would be pretty far, as I???m simply wanting rough numbers for comparison as I play with the cowl flaps etc. >> >> Does that make sense? >> >> Steve >> >> >> >>> On 8 Aug 2020, at 9:14 am, Finn Lassen finn.lassen@verizon.net wrote: >>> >>> Oh, I thought you'd already worked out the polynonmial values. >>> >>> http://www.mosaic-industries.com/embedded-systems/microcontroller-projects/temperature-measurement/thermocouple/calibration-table#computing-cold-junction-voltages >>> >>> probably way overkill. >>> >>> Input from a type K (EGT) thermocouple would expect a maximum of 55mV (1370C +). >>> >>> So you may need a voltage divider, depending on the max expected outputs from the pressure sensors. >>> Then the trick will be to come up with a formula to counteract the chip's calculation. >>> >>> For the MAX6675 used in the EM3, it appears fairly simple: >>> The MAX6675 includes signal-conditioning hardware to >>> convert the thermocouple???s signal into a voltage compatible >>> with the input channels of the ADC. The T+ and T- inputs >>> connect to internal circuitry that reduces the introduction >>> of noise errors from the thermocouple wires. >>> Before converting the thermoelectric voltages into >>> equivalent temperature values, it is necessary to compensate >>> for the difference between the thermocouple >>> cold-junction side (MAX6675 ambient temperature) and >>> a 0??C virtual reference. For a type-K thermocouple, the >>> voltage changes by 41??V/??C, which approximates the >>> thermocouple characteristic with the following linear >>> equation: >>> VOUT = (41??V / ??C) ??? (TR - TAMB) >>> Where: >>> VOUT is the thermocouple output voltage (??V). >>> TR is the temperature of the remote thermocouple junction >>> (??C). >>> TAMB is the ambient temperature (??C). >>> >>> Fortunately one of the channels in my EM3 is the temp of the PCB where the chip is located (TAMB). >>> >>> Don't know what chips are used in the Dynon Skyview. >>> >>> Finn >>> >>> >>> On 8/7/2020 7:14 PM, Stephen Izett stephen.izett@gmail.com wrote: >>>> Hi Finn. >>>> >>>> The pressure transducers I have can measure from memory a differential pressure of about 40??? of water. >>>> They have a millivolt output and in the process of cooking up a set of amps and thinking about the fact that Ive used up all my Engine Monitor inputs I pondered all those unused EGT and CHT inputs with amplifiers for millivolt input. >>>> I thought about the thermocouple compensation, impedance matching and common mode currents from the egt amps (don't really have a handle on these) and decided I probably wouldn't damage them! >>>> So I just thought Id try it out. >>>> I wired one straight to an egt input and the Dynon 5v supplied, and applied some lung pressure and the dynon display showed some life. >>>> I reworked a new Polynomial and she seems to provide a linear output over my lung burst pressure which from memory is a little over 1 psi. >>>> I???m not after certifiable numbers but have built a manometer to hopefully roughly calibrate the output by playing with the Polynomial. >>>> So lots of ignorance as far as what???s happening with the electrons at the interface but the results look promising and could be so much more helpful and easier than rigging a manometer in the cockpit. >>>> >>>> Happy to have my party spoilt by someone with knowledge of the compensation circuit used in the EGT amps. >>>> >>>> Cheers >>>> >>>> Steve >>>> >>>> >>>> >>>> >>>> >>>> >>>>> On 7 Aug 2020, at 11:01 pm, Finn Lassen finn.lassen@verizon.net wrote: >>>>> >>>>> On 8/7/2020 10:00 AM, Stephen Izett stephen.izett@gmail.com wrote: >>>>>> I worked out that they interface quite nicely without any other circuitry with the Dynon Skyview's surplus EGT inputs via a new Polynomial in the sensor config settings. >>>>> I'm thinking of using my unused?? EGT inputs for current (Hall) sensors. >>>>> >>>>> How did you compensate for the EGT compensation? >>>>> >>>>> Finn >>>>> >>>>> >>>>> --- >>>>> This email has been checked for viruses by Avast antivirus software. >>>>> https://www.avast.com/antivirus >>>>> >>>>> >>>>> -- >>>>> Homepage: http://www.flyrotary.com/ >>>>> Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html >>>> -- >>>> Homepage: http://www.flyrotary.com/ >>>> Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html >>>> >>> >>> -- >>> Homepage: http://www.flyrotary.com/ >>> Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html >> >> -- >> Homepage: http://www.flyrotary.com/ >> Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html > --------------C137CE3ED7C93B17A2B027B0 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 8bit
If max from the pressure sensors is 35mV it should work very well directly with the EGT inputs. Yes, brilliant. If 1.45psi is 35mV then the Skyview should show something like 850C before you change the Skyview default EGT setting for an EGT channel. (41uV/C)

Just be aware that the temperature around the Skyview may influence the numbers. But if you're only interested in the differences between the 5 sensors and not the absolute numbers from flight to flight, it may not be a factor.

A temperature probe on the Skyview, logged to one of the channels, should let you correct the EGT-Pressure channel values in the spreadsheet for zero-offset.

Actually if the difference in Skyview ambient temperature is only 10 to 20C, it may prove insignificant (0.41 to 0.82mV compared to the 35mV). In other words, an 8C difference in ambient temperature should only give a 1% offset error in your pressure readings. Don't know if you can even calibrate the EGT-Pressure inputs with a manometer that accurately.

Finn

On 8/7/2020 9:50 PM, Stephen Izett stephen.izett@gmail.com wrote:
So Finn. The fuller story is.

I???m thinking I need to make up a string of 5 amps for my 5 transducers that I have already, to condition the few millivolts to 0-3.3v for a pic micro or the sort.
Then I???m thinking how do I read and log the data.
But I???d like it synced with the dynon log data which is brilliant.
Look at a graph with pressures along side temps and speeds and altitudes???..

And then I think of the abundant excess EGT inputs that are used to that kind of millivolt input all connected and logged and displayable. Just a bit of configuration and basically no circuit and development time required.

Is it to good to be true. Maybe, but indications are its too easy.

Brilliant if it works.

Steve







On 8 Aug 2020, at 9:39 am, Stephen Izett stephen.izett@gmail.com <flyrotary@lancaironline.net> wrote:

Hi Finn
I input a polynomial based on the raw data from the transducer data sheet.
Full scale output is 35mV for 1.45psi.
Offset at 0 reading is on average 20mV.

But I thought I???d create a polynomial based on a new set of data using the water manometer incase the 'junction flux capacitor' was throwing out the readings to far.
To far would be pretty far, as I???m simply wanting rough numbers for comparison as I play with the cowl flaps etc.

Does that make sense?

Steve




On 8 Aug 2020, at 9:14 am, Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net> wrote:

Oh, I thought you'd already worked out the polynonmial values.

http://www.mosaic-industries.com/embedded-systems/microcontroller-projects/temperature-measurement/thermocouple/calibration-table#computing-cold-junction-voltages

probably way overkill.

Input from a  type K (EGT) thermocouple would expect  a maximum of 55mV (1370C +).

So you may need a voltage divider, depending on the max expected outputs from the pressure sensors.
Then the trick will be to come up with a formula to counteract the chip's calculation.

For the MAX6675 used in the EM3, it appears fairly simple:
The MAX6675 includes signal-conditioning hardware to
convert the thermocouple???s signal into a voltage compatible
with the input channels of the ADC. The T+ and T-  inputs
connect to internal circuitry that reduces the introduction
of noise errors from the thermocouple wires.
Before converting the thermoelectric voltages into
equivalent temperature values, it is necessary to compensate
for the difference between the thermocouple
cold-junction side (MAX6675 ambient temperature) and
a 0??C virtual reference. For a type-K thermocouple, the
voltage changes by 41??V/??C, which approximates the
thermocouple characteristic with the following linear
equation:
VOUT = (41??V / ??C) ??? (TR - TAMB)
Where:
VOUT is the thermocouple output voltage (??V).
TR is the temperature of the remote thermocouple junction
(??C).
TAMB is the ambient temperature (??C).

Fortunately one of the channels in my EM3 is the temp of the PCB where the chip is located (TAMB).

Don't know what chips are used in the Dynon Skyview.

Finn


On 8/7/2020 7:14 PM, Stephen Izett stephen.izett@gmail.com wrote:

Hi Finn.

The pressure transducers I have can measure from memory a differential pressure of about 40??? of water.
They have a millivolt output and in the process of cooking up a set of amps and thinking about the fact that Ive used up all my Engine Monitor inputs I pondered all those unused EGT and CHT inputs with amplifiers for millivolt input.
I thought about the thermocouple compensation, impedance matching and common mode currents from the egt amps (don't really have a handle on these) and decided I probably wouldn't damage them!
So I just thought Id try it out.
I wired one straight to an egt input and the Dynon 5v supplied, and applied some lung pressure and the dynon display showed some life.
I reworked a new Polynomial and she seems to provide a linear output over my lung burst pressure which from memory is a little over 1 psi.
I???m not after certifiable numbers but have built a manometer to hopefully roughly calibrate the output by playing with the Polynomial.
So lots of ignorance as far as what???s happening with the electrons at the interface but the results look promising and could be so much more helpful and easier than rigging a manometer in the cockpit.

Happy to have my party spoilt by someone with knowledge of the compensation circuit used in the EGT amps.

Cheers

Steve







On 7 Aug 2020, at 11:01 pm, Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net> wrote:

On 8/7/2020 10:00 AM, Stephen Izett stephen.izett@gmail.com wrote:

I worked out that they interface quite nicely without any other circuitry with the Dynon Skyview's surplus EGT inputs via a new Polynomial in the sensor config settings.

I'm thinking of using my unused?? EGT inputs for current (Hall) sensors.

How did you compensate for the EGT compensation?

Finn


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