AeroElectric-List Digest Archive

Sat 06/21/14


Total Messages Posted: 23



Today's Message Index:
----------------------
 
     1. 04:44 AM - Re: LED Ghosting (donjohnston)
     2. 05:39 AM - Re: LED Ghosting (donjohnston)
     3. 06:43 AM - Re: LED Ghosting (user9253)
     4. 07:09 AM - Re: LED Ghosting (user9253)
     5. 07:24 AM - Re: Re: LED Ghosting (Vern Little)
     6. 07:52 AM - Re: LED Ghosting (donjohnston)
     7. 08:12 AM - Re: LED Ghosting (user9253)
     8. 08:31 AM - Re: Re: LED Ghosting (Eric Page)
     9. 11:10 AM - Re: LED Ghosting (user9253)
    10. 11:32 AM - Re: LED Ghosting (donjohnston)
    11. 12:17 PM - Re: Re: LED Ghosting (Ken)
    12. 12:40 PM - Re: fuse link to replace fuse in low current applications? (David Josephson)
    13. 01:14 PM - Re: Re: LED Ghosting (rayj)
    14. 01:40 PM - Re: Re: LED Ghosting (Eric Page)
    15. 02:50 PM - Re: LED Ghosting (donjohnston)
    16. 02:55 PM - Re: LED Ghosting (user9253)
    17. 03:03 PM - Re: LED Ghosting (user9253)
    18. 03:09 PM - Re: Re: LED Ghosting (rayj)
    19. 07:28 PM - Z14 question about adding in external power Piper style jack (Jeffrey W. Skiba)
    20. 07:31 PM - Re: fuse link to replace fuse in low current applications? (Robert L. Nuckolls, III)
    21. 07:53 PM - Question about Electrically dependent engine and power based on z14 (Jeffrey W. Skiba)
    22. 09:11 PM - Re: Re: LED Ghosting (Eric Page)
    23. 10:26 PM - How to decide if a heat sink is required for a Rect Bridge (Jeffrey W. Skiba)
 
 
 


Message 1


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    Time: 04:44:18 AM PST US
    Subject: Re: LED Ghosting
    From: "donjohnston" <don@velocity-xl.com>
    henador_titzoff(at)yahoo. wrote: > Actually, he's correct, Don. Two LEDs in series will give you a failure rate of Pr1 + Pr2. The only reason I can think of to use two LEDs in series is to get twice the illumination while minimizing resistors. If you put two LEDs in parallel, each one has to have its own resistor to balance (control) the current flow through each one. > > If they are in parallel and one LED fails, then at least you'll have half the original illumination to indicate a failed LED. If you accept Pr1 + Pr2 as your failure rate, then it's your choice. > > Henador Titzoff > > I'm using two LEDs for brightness and reducing the resistor. I am well aware that a failure of one LED will result in a failure of indication. Thank you. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=425196#425196


    Message 2


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    Time: 05:39:14 AM PST US
    Subject: Re: LED Ghosting
    From: "donjohnston" <don@velocity-xl.com>
    Attached is my plan for implementing the MOSFET. I have a feeling (given the voltage at S is going to be pretty much non-existent) that the 12v connection to G is going to be needed. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=425197#425197 Attachments: http://forums.matronics.com//files/mosfet_196.pdf


    Message 3


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    Time: 06:43:52 AM PST US
    Subject: Re: LED Ghosting
    From: "user9253" <fransew@gmail.com>
    The the brightness problem will likely be solved by the MOSFET transistor as long as it does not drop much voltage. If it doesn't work out and it is desired not to use a relay, then another option is to make the other LED circuits drop the same same voltage as the Engine Analyzer Alarm solid state switch, which is 1.5 to 1.6 volts according to your voltage measurements. An easy way to drop that voltage is to add a red LED in series to the other annunciator circuits. Then each LED circuit will have the same voltage drop. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=425199#425199


    Message 4


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    Time: 07:09:49 AM PST US
    Subject: Re: LED Ghosting
    From: "user9253" <fransew@gmail.com>
    The output of the Engine Analyzer Alarm should not be connected directly to positive voltage because it will be a short circuit. Connect a 10K resistor between the gate and source instead. The dimmer output should be connected directly to the MOSFET source. The load (LEDs and resistor) should be connected between the drain and ground. A zener diode (15 to 20 volts) could be connected between the gate and source to protect the MOSFET against voltage spikes. Someone please correct me if I am wrong. I do not want to give bad advice. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=425200#425200


    Message 5


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    Time: 07:24:07 AM PST US
    From: "Vern Little" <sprocket@vx-aviation.com>
    Subject: Re: LED Ghosting
    The inherent inversion of this circuit will turn the lamp on when the EMS turns it off... not so good. Vern -----Original Message----- From: donjohnston Sent: Saturday, June 21, 2014 5:37 AM Subject: AeroElectric-List: Re: LED Ghosting Attached is my plan for implementing the MOSFET. I have a feeling (given the voltage at S is going to be pretty much non-existent) that the 12v connection to G is going to be needed. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=425197#425197 Attachments: http://forums.matronics.com//files/mosfet_196.pdf


    Message 6


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    Time: 07:52:01 AM PST US
    Subject: Re: LED Ghosting
    From: "donjohnston" <don@velocity-xl.com>
    user9253 wrote: > The output of the Engine Analyzer Alarm should not be connected directly to positive voltage because it will be a short circuit. Connect a 10K resistor between the gate and source instead. > The dimmer output should be connected directly to the MOSFET source. The load (LEDs and resistor) should be connected between the drain and ground. > A zener diode (15 to 20 volts) could be connected between the gate and source to protect the MOSFET against voltage spikes. > Someone please correct me if I am wrong. I do not want to give bad advice. I probably mis-interpreted the original suggestion. Thanks for the correction. user9253 wrote: > If it doesn't work out and it is desired not to use a relay, then another option is to make the other LED circuits drop the same same voltage as the Engine Analyzer Alarm solid state switch, which is 1.5 to 1.6 volts according to your voltage measurements. An easy way to drop that voltage is to add a red LED in series to the other annunciator circuits. Then each LED circuit will have the same voltage drop. That was my original backup plan. I thought that there would be a better solution. And this is on a PCB. I have a little flexibility (adding a resistor or two), but adding another LED wouldn't work. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=425202#425202


    Message 7


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    Time: 08:12:47 AM PST US
    Subject: Re: LED Ghosting
    From: "user9253" <fransew@gmail.com>
    > this is on a PCB. I have a little flexibility (adding a resistor or two), but adding another LED wouldn't work. I did not mean to locate a red LED next to the other LEDs. I meant to add a red LED on the circuit board, out of sight. It can mounted as easily as a resistor. Red LEDs have about the same voltage drop as the Engine Analyzer Alarm, which is about 1.5 volts. With each LED circuit dropping the same voltage, they should have the same brightness, in theory anyway. I have never built this circuit. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=425203#425203


    Message 8


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    Time: 08:31:31 AM PST US
    From: Eric Page <edpav8r@yahoo.com>
    Subject: Re: LED Ghosting
    Don & Joe,=0A=0AI think this is a case of there being more than one way to skin a cat.- Joe is just changing the MOSFET from a low-side to a high-si de switch, which will work fine as well.=0A=0AThe gate zener isn't a bad id ea (it will protect the gate against wild voltage excursions on the bus), b ut is probably unnecessary; this MOSFET will tolerate a 30V difference betw een gate and source.- For the same reason, it's safe to use 12V as gate p ull-up (through a resistor!) instead of the variable dimmer output. -Agai n, pay your money and take your choice.=0A=0ADefinitely heed Joe's advice r e *not* tying the gate directly to 12V.- This would probably not end well for your engine analyzer's alarm circuit!=0A=0AI've attached a diagram of my suggestion. -Let me know if it doesn't come through.=0A=0AEric=0A=0A =0AOn Jun 21, 2014, at 7:08 AM, "user9253" <fransew@gmail.com> wrote:=0A> T he output of the Engine Analyzer Alarm should not be connected directly to positive voltage because it will be a short circuit.- Connect a 10K resis tor between the gate and source instead.=0A> The dimmer output should be co nnected directly to the MOSFET source.- The load (LEDs and resistor) shou ld be connected between the drain and ground.=0A> A zener diode (15 to 20 v olts) could be connected between the gate and source to protect the MOSFET against voltage spikes.=0A> Someone please correct me if I am wrong.- I d o not want to give bad advice.=0A> =0A> --------=0A> Joe Gores


    Message 9


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    Time: 11:10:16 AM PST US
    Subject: Re: LED Ghosting
    From: "user9253" <fransew@gmail.com>
    To turn on a P-channel MOSFET, a negative voltage must be applied to the gate with respect to the source. If the load is connected between the source and positive supply, then the source is positive when the MOSFET is off. But as soon as the MOSFET starts to conduct, the source will then become negative and the gate is no longer negative in respect to the source. The MOSFET will then shut off, (if it ever actually turned on) Here is a website that shows how N-Channel and P-Channel MOSFETs are wired. http://electronics.stackexchange.com/questions/3599/basic-p-type-mosfet-question -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=425211#425211


    Message 10


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    Time: 11:32:11 AM PST US
    Subject: Re: LED Ghosting
    From: "donjohnston" <don@velocity-xl.com>
    Unfortunately, I am way outside my element. Not quite sure how to wire this sucker now. :( Read this topic online here: http://forums.matronics.com/viewtopic.php?p=425212#425212


    Message 11


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    Time: 12:17:34 PM PST US
    From: Ken <kleh@dialupatcost.ca>
    Subject: Re: LED Ghosting
    If Radio Shack still sells the paperback comic style books by Forrest Mimms III, there is a great go to book for simple circuits "Getting Started in Electronics" cat.No. 276-5003. My copy was $3.59 years ago and as an occasional hobbyist I often refer to it when starting a new project. Highly recommended for understanding and wiring this circuit. Ken On 21/06/2014 2:31 PM, donjohnston wrote: > > Unfortunately, I am way outside my element. Not quite sure how to wire this sucker now. :( > >


    Message 12


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    Time: 12:40:50 PM PST US
    From: David Josephson <dlj04@josephson.com>
    Subject: Re: fuse link to replace fuse in low current applications?
    >The concept of a "fuse" to keep faults in a tachometer from >disabling an ignition needs to be stamped out, it is a dangerous >misconception. I know of at least one incident where this almost >caused a fatal crash. It takes very little current through a P lead >from a magneto or points wire in a Kettering ignition to disrupt >performance of the ignition. Can you depend on this amount of >current blowing a fuse? Is the resistor going to open if there is a >fault? Is the engine going to keep running well if the far end of >the resistor is shorted to ground or +12? Not unless it has been >tested to do so. Yes . . . these techniques have been tested many times . . . except for the fuse . . . I don't recall seeing fuses recommended for this application but agreed . . . they're a bad idea. Having said that, let us consider the use of resistors to sample the really trashy signal that appears across the points of either a magneto or Kettering system. <snip> Yes, a resistor would be the right answer, and easy enough to test for whether ignition operation is compromised. >tach could also yield failsafe operation but that's still putting a >lot of faith in something you haven't tested. The "proof by >assertion" that I've seen from a few instrument vendors isn't really >confidence-inspiring. I've never heard of this being an issue. I've sampled p-lead and Kettering points through resistive attenuators dozens of times over the years with nary a concern for any ill effects being reflected back to the source. The case I'm aware of involves a glass-cockpit display and a points-and-coil ignition, which when connected to the ignition lead caused missing, and would sometimes cut out entirely at higher rpm. I do not know what the failure mode was, but the makers of this device didn't seem to understand that the spikes on the line could easily exceed 200 volts. It was rumored that the bypass capacitors on the input lines were rated at 50 volts, although I have not confirmed that (which is also why I am not identifying the device.) You can see what would happen if the spikes caused arcing in a bypass cap, which then failed. The point is, an external resistor would both provide the attenuation needed and prevent a failure. You could test it by grounding the instrument end, or connecting it to +12, and confirming the engine would still run properly no matter what happened. Magneto p-lead signals are really trashy, I have found it useful to run the attenuated signal through 4 poles of band pass filtering before squaring it up to drive the digital interpreters. A fuse doesn't even make sense. The signal being observed is WAAYyyyy to big as a digital signal source . . . attenuation on the order of 30:1 is the first thing you need to do with it. Yes, that's what I was responding to. Much earlier in this thread, someone suggested that a fuse would prevent an instrument failure from compromising the ignition. It won't. David Josephson


    Message 13


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    Time: 01:14:50 PM PST US
    From: rayj <raymondj@frontiernet.net>
    Subject: Re: LED Ghosting
    Just finished reading it, I second the recommendation. Raymond Julian Kettle River, MN The things we admire in men, kindness and generosity, openness, honesty, understanding and feeling are the concomitants of failure in our system. And those traits we detest, sharpness, greed, acquisitiveness, meanness, egotism and self-interest are the traits of success. And while men admire the quality of the first they love the produce of the second. -John Steinbeck, novelist, Nobel laureate (1902-1968) On 06/21/2014 02:13 PM, Ken wrote: > > If Radio Shack still sells the paperback comic style books by Forrest > Mimms III, there is a great go to book for simple circuits "Getting > Started in Electronics" cat.No. 276-5003. My copy was $3.59 years ago > and as an occasional hobbyist I often refer to it when starting a new > project. Highly recommended for understanding and wiring this circuit. > Ken > > On 21/06/2014 2:31 PM, donjohnston wrote: >> <don@velocity-xl.com> >> >> Unfortunately, I am way outside my element. Not quite sure how to >> wire this sucker now. :( >> >> > >


    Message 14


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    Time: 01:40:12 PM PST US
    Subject: Re: LED Ghosting
    From: Eric Page <edpav8r@yahoo.com>
    Gents, Sorry, I was apparently groggy this morning and had N and P-channel devices mixed up in my head. Joe is absolutely correct; please ignore my earlier diagram. I'm not at my computer and won't be for several days, so I can't make a new one. I'll try to explain it in words... 1. Connect dimmer output directly to MOSFET source. 2. At MOSFET drain, install current limiting resistor and LEDs in series, with the last LED connected to ground. 3. Install a pull-up resistor of 10-100k between MOSFET gate and source. 4. Connect engine analyzer alarm output to MOSFET gate. So, two connections at source: dimmer output and pull-up resistor. One connection at drain: resistor and LED string. Two connections at gate: pull-up resistor and alarm output. Hope that's understandable. Best I can do standing in an airport terminal waiting to board... Cheers, and sincere apologies for causing so much confusion! Thank you, Joe. Good to have smart guys QC-ing everything on here. Eric On Jun 21, 2014, at 11:09 AM, "user9253" <fransew@gmail.com> wrote: > To turn on a P-channel MOSFET, a negative voltage must be applied to the gate with respect to the source. If the load is connected between the source and positive supply, then the source is positive when the MOSFET is off. But as soon as the MOSFET starts to conduct, the source will then become negative and the gate is no longer negative in respect to the source. The MOSFET will then shut off, (if it ever actually turned on) > Here is a website that shows how N-Channel and P-Channel MOSFETs are wired. http://electronics.stackexchange.com/questions/3599/basic-p-type-mosfet-question > > -------- > Joe Gores


    Message 15


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    Time: 02:50:35 PM PST US
    Subject: Re: LED Ghosting
    From: "donjohnston" <don@velocity-xl.com>
    Okay... The MOSFET approach isn't going to work. :( The LEDs and resistors are on a circuit board. This type of change isn't going to work given the constraints of the board. So I guess I'll have to fall back to my plan B and add resistors to dim all the other LEDs so they're about the same as that pesky engine analyzer. Maybe Bob will have an idea. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=425221#425221


    Message 16


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    Time: 02:55:51 PM PST US
    Subject: Re: LED Ghosting
    From: "user9253" <fransew@gmail.com>
    > Unfortunately, I am way outside my element. Not quite sure how to wire this sucker now. Not to worry, use Eric's (edpav8r) last post as a guide and draw a new circuit. Post it and others will offer suggestions. Diodes added to the bright LED circuits is starting to look easier, if it works. I think that it is worth a try. Two of 1N4148 in series will drop about 1.5 volts when conducting 20 ma and will drop 1.6 volts at 30 ma, according to the data sheet. That will equal the voltage drop across the Engine Analyzer Alarm and hopefully make all LEDs the same brightness. I have some extra diodes that I could mail to you if you wanted to try them. Of course you already have the P-Channel MOSFET. Use this circuit http://electronics.stackexchange.com/questions/3599/basic-p-type-mosfet-question and ignore the N-Channel circuit. Substitute your dimmer for the power supply, use your 390 ohm for the load resistor. Put your LED in series with the 390 ohm load resistor. Connect the Engine Analyzer Alarm output and the pull-up resistor to the gate. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=425222#425222


    Message 17


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    Time: 03:03:05 PM PST US
    Subject: Re: LED Ghosting
    From: "user9253" <fransew@gmail.com>
    Dan, I would try adding 2 diodes in series instead of adding resistors. The diodes are very small, maybe even smaller than the resistors that you have. They should fit on the circuit board. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=425223#425223


    Message 18


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    Time: 03:09:30 PM PST US
    From: rayj <raymondj@frontiernet.net>
    Subject: Re: LED Ghosting
    Instead of dimming all the other ones. Can the problem one be replaced with a brighter one so that in it's lower than maximum light output mode, which the current one is apparently in, it is the same brightness as the others? Raymond Julian Kettle River, MN The things we admire in men, kindness and generosity, openness, honesty, understanding and feeling are the concomitants of failure in our system. And those traits we detest, sharpness, greed, acquisitiveness, meanness, egotism and self-interest are the traits of success. And while men admire the quality of the first they love the produce of the second. -John Steinbeck, novelist, Nobel laureate (1902-1968) On 06/21/2014 04:49 PM, donjohnston wrote: > > Okay... The MOSFET approach isn't going to work. :( > > The LEDs and resistors are on a circuit board. This type of change isn't going to work given the constraints of the board. > > So I guess I'll have to fall back to my plan B and add resistors to dim all the other LEDs so they're about the same as that pesky engine analyzer. > > Maybe Bob will have an idea. > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=425221#425221 > >


    Message 19


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    Time: 07:28:41 PM PST US
    From: "Jeffrey W. Skiba" <jskiba@icosa.net>
    Subject: Z14 question about adding in external power Piper style
    jack I have a question about: Z14 question about adding in external power Piper style jack I see where you can add it in to the main battery contactor on the battery side to charge the battery without having to energize the main battery cont actor, but is there a way to also supply power to the AUX battery in the sa me way? I thought about just running a wire between the two but then we just made a batterys connected at all times (not good right?) Then I thought Diode, but that would have to be one HUGE diode to handle th e power right ? [cid:image001.png@01CF8D97.6E24D740]


    Message 20


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    Time: 07:31:30 PM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: fuse link to replace fuse in low current applications?
    The case I'm aware of involves a glass-cockpit display and a points-and-coil ignition, which when connected to the ignition lead caused missing, and would sometimes cut out entirely at higher rpm. I do not know what the failure mode was, but the makers of this device didn't seem to understand that the spikes on the line could easily exceed 200 volts. It was rumored that the bypass capacitors on the input lines were rated at 50 volts, although I have not confirmed that (which is also why I am not identifying the device.) You can see what would happen if the spikes caused arcing in a bypass cap, which then failed. The point is, an external resistor would both provide the attenuation needed and prevent a failure. You could test it by grounding the instrument end, or connecting it to +12, and confirming the engine would still run properly no matter what happened. Clearly, any supplier is remiss in their duty when offering an accessory designed to get rpm data from the ignition system without vetting failure modes effects. If ANYONE becomes aware of a same or similar case, pleased let me know about it. The work-arounds are simple and safe . . . it's been done with reliability for decades. I'd be pleased to get in touch with designers to see if a fix can be implemented. It borders on foolish to spend a bucket load of $time$ on the development and marketing of otherwise useful product with easily cured nasty habits. Bob . . .


    Message 21


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    Time: 07:53:19 PM PST US
    From: "Jeffrey W. Skiba" <jskiba@icosa.net>
    Subject: Question about Electrically dependent engine and power
    based on z14 Okay second question on z14 I have a Electrically dependent engine and power based on z14 I see that we are using a rectifier diode to supply power from two sources (eng batte ry buss and aux battery buss) Which would always be hot (hence battery buss), is there a reason to not co nnecting it on the regular main buss and AUX buss (my guess would be to av oid a contactor having to be closed, but if you have two sources of power i sn't that over kill?) What am I not seeing here why we connect direct to th e battery busses ? [cid:image002.png@01CF8D9B.18462050]


    Message 22


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    Time: 09:11:58 PM PST US
    Subject: Re: LED Ghosting
    From: Eric Page <edpav8r@yahoo.com>
    Laying in bed thinking about this and couldn't sleep... On Jun 21, 2014, at 4:49 PM, "donjohnston" <don@velocity-xl.com> wrote: > Okay... The MOSFET approach isn't going to work. :( > > The LEDs and resistors are on a circuit board. This type of change isn't going to work given the constraints of the board. Don, I presume this is because your board has a common trace that feeds dimmer output to all of the cells in the annunciator panel, with each cell separately switched to ground for activation. If so, could you use a razor blade to cut the PCB trace for this "dimmer bus" on either side of the oil pressure cell, install a jumper wire to bypass this cell, then feed the oil pressure cell directly from the MOSFET drain? Eric


    Message 23


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    Time: 10:26:38 PM PST US
    From: "Jeffrey W. Skiba" <jskiba@icosa.net>
    Subject: How to decide if a heat sink is required for a Rect
    Bridge T2theSBJIGhhdmUgdGhlc2UgUmVjdCBCcmlkZ2UNCg0KR0JQQyBTZXJpZXM8aHR0cDovL3d3dy52 aXNoYXkuY29tL2RvYz85MzU3NT4NCg0KRGlnaWtleSBnYnBjMzUwMmENCg0KDQoNCjM1IGFtcCB2 ZXJzaW9uDQoNCg0KDQoNCg0KSSBwbGFuIEkgdXNpbmcgdGhlbSB0byBjb25uZWN0IGEgZGV2aWNl IGZyb20gdHdvIGRpZmZlcmVudCBkYyBiYXR0ZXJpZXMNCg0KVG8gcnVuIGEgbG9hZCBvZiBhYm91 dCA2IGFtcHMgY29udGludW91cw0KDQpUaGlzIGlzIGEgY29tcG9zaXRlIGFpcmZyYW1lIHNvIG5v IHBsYWNlIHRvIGJvbHQgZGlyZWN0bHkgdG8gbWV0YWwNCg0KDQoNCjEpICAgICAgSXMgYSBoZWF0 IHNpbmsgcmVxdWlyZWQgPw0KDQoyKSAgICAgIFdvdWxkIGl0IGJlIGEgZ29vZCBpZGVhIGlmIG9u ZSBpcyBub3QgcmVxdWlyZWQNCg0KMykgICAgICBIb3cgZG8gd2UgdGVsbCBob3cgYmlnIG9mIGEg aGVhdCBzaW5rIHdlIG5lZWQgPw0KDQoNCg0KDQoNCldvdWxkIGEgZGlnaWtleSBwYXJ0IG51bWJl ciBoczExNCAgd29yayBwcm9wZXJseSA/DQoNCkhvdyBjYW4gd2UgdGVsbCA/DQoNCg0KDQpUaGFu a3MNCg0KSmVmZi4NCg=




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