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Bob's Email Outage - Missed Threads?

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Eric Page

Joined: 15 Feb 2017
Posts: 244

Posted: Sat Aug 12, 2023 8:51 am Post subject: Bob's Email Outage - Missed Threads?

Posted in another thread:



 	  nuckollsr wrote: 	
		  Sorry for the relative silence. My email service has been on the fritz (on account of new Google 'security' features) for several weeks. I think we're close to resolving the issues. So for you folks that are missing replies from me . . . especially those with gmail accounts . . . I expect to be up and running shortly. 	


Hi Bob -- sorry to hear that you've been incommunicado lately.  I posted a couple of threads recently on which I was hoping to get your feedback. Perhaps they appeared during your comms outage?  Links to those threads follow.



Overvoltage Protection for Rotax 9-Series Engines

http://forum.matronics.com/viewtopic.php?t=16780921



Starter Circuit: Verner 7U Radial

http://forum.matronics.com/viewtopic.php?t=16780986



Thanks,



Eric



do not archive

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nuckolls.bob(at)aeroelect
Guest

Posted: Mon Aug 14, 2023 8:19 am Post subject: Bob's Email Outage - Missed Threads?

 	  Quote: 	
		  Hi Bob -- sorry to hear that you've been incommunicado lately.  I posted a couple of threads recently on which I was hoping to get your feedback. Perhaps they appeared during your comms outage?  Links to those threads follow.



 Overvoltage Protection for Rotax 9-Series Engines

  http://forum.matronics.com/viewtopic.php?t=16780921 	


  

 In a forum thread that I started in October 2021 about using a Rotax 912iS on my Kitfox, there was some discussion about my use of crowbar overvoltage protection (OVP). In that thread, Joe Gores asked, "Can it be designed to just open the relay without blowing a 1 amp fuse?" It turns out that, yes, it can. After several prototypes, I have a non-crowbar OVP Module for Rotax 9-series engines. See the attached PDF document. 



     Good work Eric!



     Of course, this becomes a classic ov protection relay that simply

     latches off in response to an ov event and needs to be reset

     by action of the pilot.



     My very first task at Electro-Mech back

     in the dark ages was for just such a device.

     If memory serves, the trip response for that first effort was

     sd in the Cessna procurement specification was:



     A step response from nominal bus voltage of 14.2 to

     20.0 would produce a shutdown in 60 +/- 10 milliseconds.

     As a matter of fact, this was an unnecessarily short-

     coupled requirement.



     DO-160/Mil-STD-704 dictates even back then called for

     a certifiable appliance to withstand a 20V excursion

     for 1 Second; a 40V excursion for 100 milliseconds.



     The 60Ms requirement led to some 'twitchy' designs.

     Nonetheless, design goals for ov protection were

     pretty similar across the industry. Tens of thousands

     of such devices were manufactured and successfully

     operated in the GA fleet.



     I don't recall the exact time-frame but 

     around 1980, while crafting a response to a 

     request for proposal from Beech, I suggested that

     their response profile be adjusted to 500+/-50

     Milliseconds for a 16V setpoint. With trip

     time being independent of magnitude of ov

     event. Further, if bus voltage dropped below

     16v at any time before the 500 Ms trip target,

     the timer resets to zero.



     That produced a vociferous barrage of 'incoming'

     from various factions at Beech. While all the

     electron-herders agreed that the change would

     produce a perfectly adequate and less twitchy

     design, making such a change would generate

     a boat load of re-certification efforts across

     several venues.



     A classic example of "Once certified: carved

     in stone" mentality. I can cite a goodly number

     of similar incidents in my GA career when a

     marginal (if not poor) condition was allowed

     to persist due to cost of running the re-cert

     guantlet.



     Just for grins, I've sketched up a somewhat

     modernized version of that proposal and attached

     it to this posting. Input to the voltage sense

     comparator need not be filtered for short

     transients/noise due to the auto reset feature.



     The two comparators are 'open collector' devices

     so voltage sense need only pull down on the RC

     timing capacitor. If the voltage sense comparator

     stays 'open' for the requisite time, the second

     comparator will trip and turn on a beefy FET

     to supply the crowbar effect. Replacing the

     SCR with the FET eliminates one of the 'problem

     children' of the legacy design.



     With a little shuffling of the schematic,

     this might be convertable to a relay driver

     that would control the AC side of a PM

     Dynamo system. I'll pray over that idea

     a bit.



     Did a quick pass at a board layout and I think

     all the parts fit on the same size board as

     our original 9003 CBOV module; about 1.1 x

     0.5 inches.  Out here in Podunk Kansas I think

     I might find some kids who would like to learn

     how to assemble the critters. We may just resurrect

     the 9003 program with a modernized version of

     the design I proposed 40+ years ago.



 



 

   Bob . . .



                    //// 

                   (o o) 

    ===========o00o=(_)=o00o========= 

    < Go ahead, make my day . . .   > 

    < show me where I'm wrong.      > 

    =================================

  

    In the interest of creative evolution

    of the-best-we-know-how-to-do based

    on physics and good practice.

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finn.lassen(at)verizon.ne
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Posted: Mon Aug 14, 2023 12:33 pm Post subject: Bob's Email Outage - Missed Threads?

On 8/14/2023 12:18 PM, Robert L.       Nuckolls, III wrote:

     

      	  Quote: 	
		                 	  Quote: 	
		  Hi Bob           -- sorry to           hear that you've been incommunicado lately.� I posted a couple           of           threads recently on which I was hoping to get your feedback.           Perhaps they           appeared during your comms outage?� Links to those threads           follow.

           

           Overvoltage Protection for Rotax 9-Series Engines

                        http://forum.matronics.com/viewtopic.php?t=16780921       	
       

              

           In a forum thread that I started in October 2021 about using a           Rotax           912iS on my Kitfox, there was some discussion about my use of           crowbar           overvoltage protection (OVP). In that thread, Joe Gores asked,           "Can           it be designed to just open the relay without blowing a 1 amp           fuse?"           It turns out that, yes, it can. After several prototypes, I           have a           non-crowbar OVP Module for Rotax 9-series engines. See the           attached PDF           document. 

           

           ��� Good work Eric!

         

         ��� Of course, this becomes a classic ov protection           relay that simply

           ��� latches off in response to an ov event and needs to be           reset

           ��� by action of the pilot.

           

           ��� My very first task at Electro-Mech back

           ��� in the dark ages was for just such a device.

         ��� If memory serves, the trip response for that first         effort was

         ��� sd in the Cessna procurement specification         was:

         

         ��� A step response from nominal bus voltage of 14.2         to

         ��� 20.0 would produce a shutdown in 60 +/- 10         milliseconds.

         ��� As a matter of fact, this was an unnecessarily         short-

         ��� coupled requirement.

         

         ��� DO-160/Mil-STD-704 dictates even back then called         for

         ��� a certifiable appliance to withstand a 20V         excursion

         ��� for 1 Second; a 40V excursion for 100         milliseconds.

         

         ��� The 60Ms requirement led to some 'twitchy'         designs.

         ��� Nonetheless, design goals for ov protection were

         ��� pretty similar across the industry. Tens of         thousands

         ��� of such devices were manufactured and         successfully

         ��� operated in the GA fleet.

         

         ��� I don't recall the exact time-frame but 

         ��� around 1980, while crafting a response to a 

         ��� request for proposal from Beech, I suggested that

         ��� their response profile be adjusted to 500+/-50

         ��� Milliseconds for a 16V setpoint. With trip

         ��� time being independent of magnitude of ov

         ��� event. Further, if bus voltage dropped below

         ��� 16v at any time before the 500 Ms trip target,

         ��� the timer resets to zero.

         

         ��� That produced a vociferous barrage of 'incoming'

         ��� from various factions at Beech. While all the

         ��� electron-herders agreed that the change would

         ��� produce a perfectly adequate and less twitchy

         ��� design, making such a change would generate

         ��� a boat load of re-certification efforts across

         ��� several venues.

         

         ��� A classic example of "Once certified: carved

         ��� in stone" mentality. I can cite a goodly         number

         ��� of similar incidents in my GA career when a

         ��� marginal (if not poor) condition was allowed

         ��� to persist due to cost of running the re-cert

         ��� guantlet.

         

         ��� Just for grins, I've sketched up a somewhat

         ��� modernized version of that proposal and attached

         ��� it to this posting. Input to the voltage sense

         ��� comparator need not be filtered for short

         ��� transients/noise due to the auto reset         feature.

         

         ��� The two comparators are 'open collector' devices

         ��� so voltage sense need only pull down on the RC

         ��� timing capacitor. If the voltage sense comparator

         ��� stays 'open' for the requisite time, the second

         ��� comparator will trip and turn on a beefy FET

         ��� to supply the crowbar effect. Replacing the

         ��� SCR with the FET eliminates one of the 'problem

         ��� children' of the legacy design.

         

         ��� With a little shuffling of the schematic,

         ��� this might be convertable to a relay driver

         ��� that would control the AC side of a PM

         ��� Dynamo system. I'll pray over that idea

         ��� a bit.

         

         ��� Did a quick pass at a board layout and I think

         ��� all the parts fit on the same size board as

         ��� our original 9003 CBOV module; about 1.1 x

         ��� 0.5 inches.� Out here in Podunk Kansas I         think

         ��� I might find some kids who would like to learn

         ��� how to assemble the critters. We may just         resurrect

         ��� the 9003 program with a modernized version of

         ��� the design I proposed 40+ years ago.

         

         

         

                

           � Bob . . .

           

           ������������������           //// 

           �����������������           (o o) 

           �� ===========o00o=(_)=o00o========= 

           �� < Go ahead, make my day . . .�� > 

           �� < show me where I'm wrong.�����           > 

           �� =================================

           �

           �� In the interest of creative evolution

           �� of the-best-we-know-how-to-do based

           �� on physics and good practice.

                     	
     

Looks promising. Do you have a schematic with part numbers? I'm       not familiar with the zener diode symbol with a third pin (input)       which appear to stabilize the 10V reference.     

Finn

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Eric Page

Joined: 15 Feb 2017
Posts: 244

Posted: Mon Aug 14, 2023 9:13 pm Post subject: Re: Bob's Email Outage - Missed Threads?

Thank you, Bob.  Much appreciated!



Did you have a second to look at the other thread too?



Starter Circuit: Verner 7U Radial

http://forum.matronics.com/viewtopic.php?t=16780986



Cheers,



Eric

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