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  #11  
Old 09-12-2017, 06:20 AM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 664
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Quote:
Originally Posted by f1rocket View Post
As far as I know, the tractor regulator I put in my -12 is still going strong in the Texas heat 300 hours later.
Likewise, Ducati VR failed at 100TT and was replaced with John Deere AM101406 - does nice job maintaining battery voltage at 14V.

VR mounted on firewall shelf in original location with new 1/8" aluminum sub base for heat dissipation. Used heat transfer paste at the VR / sub plate.

Now 280TT and going strong. I don’t like electrical failures, so I have a 2nd JD on the shelf for $27.99 free shipping from eBay.
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Jim Stricker
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80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC 7/12 Bought Flying 10/2015 with 48TT - Hobbs now 288
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  #12  
Old 09-12-2017, 09:57 AM
todehnal todehnal is offline
 
Join Date: Jan 2005
Location: Kentucky Lakes area in KY
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Hey Jim, are those true OEM John Deere AM101406 parts, or aftermarket regulators.................Tom
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2013- RV12, Kit #119. N123M First flight Nov21. It's a keeper!
1998- RV-9 tail kit, built and sold
1989- RV-6 tail kit, built and sold
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  #13  
Old 09-12-2017, 02:35 PM
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Piper J3 Piper J3 is offline
 
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Quote:
Originally Posted by todehnal View Post
Hey Jim, are those true OEM John Deere AM101406 parts, or aftermarket regulators.................Tom
I'm pretty sure they are Chinese aftermarket...
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Jim Stricker
Hinckley, Ohio
PPL - 1970
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC 7/12 Bought Flying 10/2015 with 48TT - Hobbs now 288
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  #14  
Old 09-13-2017, 11:10 PM
keitht keitht is offline
 
Join Date: Jun 2016
Location: coupeville wa
Posts: 5
Default Regulator failures

The Ducati regulator is a marginal unit both from an electrical design, thermal design and mechanical design viewpoint. A friend with a RV-12 had a Ducati regulator fail within the first 40 hr of flight time. I carefully took the unit apart to determine the cause of failure and determine the circuit configuration.
The circuit uses a bridge rectifier configuration with two SCRs in opposing legs of the bridge. The firing angle of the SCRs is varied as the output voltage of the generator winding changes with engine rpm and electrical load to provide the regulated output. The SCRs used in the unit I took apart have a very high saturation voltage ( based on the data sheet for the part) so the efficiency of the unit and consequential thermal losses would result in high unit temperatures. The design of the control circuit is almost identical to a readily available circuit schematic available on the web. Ciruit component values were a little different but the topology was the same. The thermal design and mechanical design were very poor. Both SCRs and one power diode in the bridge had failed in a short circuit mode typical of an over temp condition. Analysis of the control circuit showed that not getting a good 12 volt reference could result in unstable operation of the regulator and induce premature failure. The airplane wiring schematic shows the 12 volt reference to the regulator going through a large number of connections to go from the master relay to the regulator. The regulator was replaced and the 12 volt reference wired directly from the master relay to the regulator. The location of the regulator on the engine side of the firewall was left the same. So far the second regulator has over 120 hr and 12 months of operation without failure. The Ducati regulator is truly a weak link in the electrical system for the RV-12. I was hoping there would have been a robust alternative by this time.
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  #15  
Old 09-13-2017, 11:43 PM
keitht keitht is offline
 
Join Date: Jun 2016
Location: coupeville wa
Posts: 5
Default Regulators

Another consideration when swapping out the Ducati regulator for some other alternative.
The engine alternator windings are in the same magnetic circuit as both ignition circuit generator windings. So theoretically saturation of the generator magnetic circuit could result in no voltage to the two ignition circuits and engine stoppage. I dont know if this is a practical possibility - would very much depend on the tightness of the magnetic coupling and the saturation characteristics of the engine generator. Since it is unlikely that Rotax would provide any electrical design data on which to base a more detailed analysis the only way to be sure that a regulator failure couldnt take out the ingnition circuit would be through extensive testing
Just a concern about using any new regulator without detailed analysis and testing.
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  #16  
Old 09-13-2017, 11:50 PM
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magiccarpet magiccarpet is offline
 
Join Date: Feb 2013
Location: Switzerland, Europe
Posts: 139
Default Get the SH regulator for less

Quote:
Originally Posted by todehnal View Post
How are you guys doing who have replaced your original Ducati with the Silent Hektik design? Too bad they are so hard to get, and the cost is so high; nearly $300 shipped from a motorcycle dealer in England.
Tom
Simply order the VR directly from the manufacturer. According to their web site they ask
165.- (excl. tax) for it
https://www.silent-hektik.de/UL_R_912.htm
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  #17  
Old 09-14-2017, 06:32 AM
vic syracuse vic syracuse is offline
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Join Date: May 2005
Location: Locust Grove, GA
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Default Cold solder joint

Out of curiosity I took apart the failed regulator to understand the root cause. It was a cold solder joint on a large wire on the printed circuit board. Clearly the board is wave soldered and that might not be the best for large wire protrusions. I had to use a Weller 100W soldering iron to get it to form a good solder joint, and then I tested it on the aircraft.
Worked like a champ, with 13.7 volts right at startup and solid battery charge of 5 amps and decreasing (meaning the battery was completing its charge). Prior to that I had 11.5 volts showing on the battery and -6 amps discharge.

Vic
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  #18  
Old 09-14-2017, 07:24 AM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 2,495
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Quote:
. . . . the 12 volt reference wired directly from the master relay to the regulator.
The disadvantage of doing that is that there is no way to shut off electrical power in case of smoke in the cockpit. Shutting off the master contactor will not shut down the charging system because the "C" terminal will still be energized by the regulators output. I know because I experimented. When wired per above, everything kept right on working when the master switch was shut off, although the voltage was unstable, varying plus and minus about a volt or so, setting off the Dynon high voltage alarm.
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  #19  
Old 09-14-2017, 11:01 AM
todehnal todehnal is offline
 
Join Date: Jan 2005
Location: Kentucky Lakes area in KY
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Quote:
Originally Posted by magiccarpet View Post
Simply order the VR directly from the manufacturer. According to their web site they ask
165.- (excl. tax) for it
https://www.silent-hektik.de/UL_R_912.htm
Yeah, that's easy for you, living in Switzerland. I emailed them and they do not ship to the USA. That means that we have to order through a 3rd party, and the only source I could find was a Moto Guzzi dealer in Europe who does ship to the USA. That is where the $300 US quote came from. Lucky you!

Tom
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1998- RV-9 tail kit, built and sold
1989- RV-6 tail kit, built and sold
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