AeroElectric-List Digest Archive

Mon 03/06/06


Total Messages Posted: 7



Today's Message Index:
----------------------
 
     1. 06:21 AM - Re: Re: Backup battery - Lightspeed EI (Brian Lloyd)
     2. 06:38 AM - bursting bubbles (Ernest Christley)
     3. 07:02 AM - Re: Composite planes, Metallic paint, Antennae (Jim Wickert)
     4. 07:26 AM - Re: bursting bubbles (Robert L. Nuckolls, III)
     5. 12:36 PM - Power reqmts - buss evaluation? (Alan K. Adamson)
     6. 07:06 PM - Re: Zener Diodes and LEDs (Tim & Diane Shankland)
     7. 07:20 PM - Thanks for LED Help (Dennis Johnson)
 
 
 


Message 1


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    Time: 06:21:50 AM PST US
    From: Brian Lloyd <brian-yak@lloyd.com>
    Subject: Re: Backup battery - Lightspeed EI
    --> AeroElectric-List message posted by: Brian Lloyd <brian-yak@lloyd.com> Robert L. Nuckolls, III wrote: > Yeah . . . I've had some conversation with the folks at WestMountainRadio > about this. Obviously, the ampere-hour is NOT a measure of energy. But it is easily converted into energy (amp-hours x volts = watt-hours) and it more readily conforms to how a battery works. Good batteries tend to have very high coulombic efficiency (one coulomb removed requires one coulomb to be replaced). I am used to batteries with coulombic efficiencies on the order of 97%. The energy loss in a battery is a function of the voltages involved, i.e. you need a higher voltage to push the coulombs back into the battery than you get when taking them out. (For those of you wondering what I am talking about, a coulomb is the measure of a pot full of electrons. An amp is one coulomb of electrons flowing through a wire in one second. Think of the cell of a battery as a tank full of coulombs of electrons.) > When > I purchased my first battery tester from them, I suggested some enhancements > for the next release of their software. We engineers would really like to > see constant wattage and constant resistance discharge functions in addition > to the standard constant current function. Then too, as you've noted, a > volts vs. time and energy vs. time plots would be more meaningful along > with an box on the graph that displayed watt-seconds of energy at the > endpoint. > He seemed receptive. I'll write again and see where that might set on his > stove's burners. Well, then let's build our own. Not hard to do. It is just some simple hardware and then SMOP (small matter of programming). Hardware consists of a load bank made up of a bunch of paralleled MOSFETs driven from a D:A converter. (Use MOSFETs because they won't current hog.) The battery voltage and current is measured by an A:D converter. The software looks at these values and controls the load bank to make it do what you want it to do. > I'd REALLY like to recommend his tool to others in the battery business > but most would like some features besides the arcane and poorly-descriptive > ampere-hour display. He's 100% of the way there with hardware, what he > needs now is a really cool GUI. Well, the hardware is the easy part. :-) I would like to see his tester. You know, with the requirement for testing of batteries in certified aircraft, you would think there would be a market for a good, cheap battery tester. -- Brian Lloyd 361 Catterline Way brian-yak at lloyd dot com Folsom, CA 95630 +1.916.367.2131 (voice) +1.270.912.0788 (fax) I fly because it releases my mind from the tyranny of petty things . . . - Antoine de Saint-Exupery


    Message 2


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    Time: 06:38:41 AM PST US
    From: Ernest Christley <echristley@nc.rr.com>
    Subject: bursting bubbles
    --> AeroElectric-List message posted by: Ernest Christley <echristley@nc.rr.com> > >Time: 07:29:54 AM PST US >From: "Robert L. Nuckolls, III" <nuckollsr@cox.net> >Subject: AeroElectric-List: My bubble has burst . . . > > >The 20-cent cell is decidedly lower in energy content. However, >in terms of cents per milliampere hour, still a reasonable deal >since the other bargain products are pushing 37 cents per cell. > >I'll watch this product and buy another package in 6 months >to a year for a retest. The cells I have may have been produced >when the chef was having a bad day in the kitchen. > > > Bob, could you make a note of the date of manufacture that should be stamped on each battery when you do these test. It is my suspicion that you will find more correlation between capacity and DOM than capacity and cost. -- ,|"|"|, Ernest Christley | ----===<{{(oQo)}}>===---- Dyke Delta Builder | o| d |o www.ernest.isa-geek.org |


    Message 3


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    Time: 07:02:24 AM PST US
    From: Jim Wickert <jimw_btg@earthlink.net>
    Subject: Composite planes, Metallic paint, Antennae
    --> AeroElectric-List message posted by: Jim Wickert <jimw_btg@earthlink.net> Alan, Sorry fat fingers "DO Not" they are quite functional under glass and kelvar but not Carbon Fiber. Take care. Jim Wickert Vision Vair #159 -----Original Message----- >From: "Alan K. Adamson" <aadamson@highrf.com> >Sent: Mar 4, 2006 10:08 PM >To: aeroelectric-list@matronics.com >Subject: RE: AeroElectric-List: Composite planes, Metallic paint, Antennae > >--> AeroElectric-List message posted by: "Alan K. Adamson" <aadamson@highrf.com> > >Jim, thanks for the post. Can I ask for some clarification? Your quote >... "It is quite well known that foil internal antennas do function well >under carbon fiber cloth." Is that correct, or should there have been a >*NOT* before "function"? Are you trying to say, they do or do not work on >carbon? > >Second and a point of clarification. The Lancair actually uses an "outside >antenna". It uses a bent whip from ComAnt. But I wanted to improve the >"ground plane" only, so I added those 4 "radials" of 22" and the base plate >to provide the counterpoise and conductive attach points for the external >antenna. > >I know of one other Legacy that is completed this same way and he says his >Comm antenna works very well. I'm cautiously optimistic. > >But I think I'll order that $5 book just the same. > >Thanks and can ya clear up the opening quote for me? > >Alan > >-----Original Message----- >From: owner-aeroelectric-list-server@matronics.com >[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Jim >Wickert >Sent: Saturday, March 04, 2006 10:21 PM >To: aeroelectric-list@matronics.com >Subject: RE: AeroElectric-List: Composite planes, Metallic paint, Antennae > >--> AeroElectric-List message posted by: Jim Wickert >--> <jimw_btg@earthlink.net> > >Alan, > >Jim Wickert here. It is quite well known that foil internal antennas do >function well under carbon fiber cloth. they do however function very well >under glass substrate. Now with regard to paint. Per a quite an >experienced individual Jim Weir VP RST Engineering group who as published >"The Reference Text, The RST-820 Antenna which deals strictly with copper >Tape Antennas, see quote> > >"These antennas have worked in glass and fiberglass airplanes with almost >every kind of paint and dope (including the aluminum coat used on fabric as >a UV protectant) that we could find. A couple of times in the past two >years there have been reports that there is a new German metallic paint >(sorry, I don't know the brand) that makes ALL hidden antennas (not just >ours) work poorly if at all." > >I know of builder that has his plane flying with a silver metallic paint and >he has no problems. Jims Ref manual is about $5.00 and well worth the price >of admission for any laying out antennas in composite planes > >Take care, happy building > >Jim Wickert >Vision Vair #159 >Some will have it some will not!! > >-----Original Message----- >>From: "Alan K. Adamson" <aadamson@highrf.com> >>Sent: Mar 4, 2006 12:35 PM >>To: aeroelectric-list@matronics.com >>Subject: RE: AeroElectric-List: Composite planes, Metallic paint, >Antennae >> >>--> AeroElectric-List message posted by: "Alan K. Adamson" >>--> <aadamson@highrf.com> >> >>Just one comment, Radar uses a much higher frequency than Comm or Nav, >etc. >>So while the metal flake paint messes with radar returns due to it's >>"reflectivity". I doubt it would do much to the comm antenna >> >>Alan >> >>-----Original Message----- >>From: owner-aeroelectric-list-server@matronics.com >>[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of >>PTACKABURY@aol.com >>Sent: Saturday, March 04, 2006 11:38 AM >>To: aeroelectric-list@matronics.com >>Subject: Re: AeroElectric-List: Composite planes, Metallic paint, >>Antennae >> >>--> AeroElectric-List message posted by: PTACKABURY@aol.com >> >>Bob: Thanks for your prompt response to my question, BUT: I didn't >>communicate my concern well and therefore need to retransmit. I am >>not interested in a ground plane, I understand that one from your >>excellent chapter in the "Connection" and used that info when >>installing my EXTERIOR antennae. My concern is the INTERIOR antennae >>buried in the upper aft sections of the Lancair IV under the fiberglass >>skin. Again this is the recommended place for com, gps, etc and has >>been used successfully by many builders for years so I am not concerned >>about that either. HOWEVER, I am considering a metallic paint and >>wonder if the small amounts of metallic in the paint when applied over >>the fiberglass will degrade the performance of these buried antennae. >>I don't think metallic paints are used on radomes but I wonder if this >>is really a concern for my installation. thanks for giving me a >>second chance, paul >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> > > > > > > > > > > > >


    Message 4


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    Time: 07:26:20 AM PST US
    From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
    Subject: Re: bursting bubbles
    --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net> At 09:35 AM 3/6/2006 -0500, you wrote: >--> AeroElectric-List message posted by: Ernest Christley ><echristley@nc.rr.com> > > > > > >Time: 07:29:54 AM PST US > >From: "Robert L. Nuckolls, III" <nuckollsr@cox.net> > >Subject: AeroElectric-List: My bubble has burst . . . > > > > > >The 20-cent cell is decidedly lower in energy content. However, > >in terms of cents per milliampere hour, still a reasonable deal > >since the other bargain products are pushing 37 cents per cell. > > > >I'll watch this product and buy another package in 6 months > >to a year for a retest. The cells I have may have been produced > >when the chef was having a bad day in the kitchen. > > > > > > >Bob, could you make a note of the date of manufacture that should be >stamped on each battery when you do these test. It is my suspicion that >you will find more correlation between capacity and DOM than capacity >and cost. Excellent point. I know that a famous battery manufacturer has suffered a number of manufacturing runs where the chef was having a bad day. This could well be the same phenomenon. This batch of batteries are marked "best if used by Dec 2012". I suspect they were manufactured in Dec of 2005. I'll make SURE the next package I buy is a different date. Thanks for the suggestion. Bob . . .


    Message 5


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    Time: 12:36:27 PM PST US
    From: "Alan K. Adamson" <aadamson@highrf.com>
    Subject: Power reqmts - buss evaluation?
    --> AeroElectric-List message posted by: "Alan K. Adamson" <aadamson@highrf.com> All, I'm looking for a little help. I've got a panel design conceptualized, as a result I need to verify the most optimal buss, switch breaker, breaker and fuse counts. http://www.highrf.com/Rockets/Panel%20Final.jpg - Panel layout I've been using a spreadsheet that includes all the information including some tables that show busses and what's on each buss. I'm primarily focused on pull breakers, but all the detail are there for switch breakers and fuses. http://www.highrf.com/Rockets/Breaker%20Counts.xls - spreadsheet This is a dual alt/batt 24v system with a 60 or 100amp main alt, and an SD-20 as backup. It will be using a slightly modified Z14 (modified because there is an avionics master on the primary buss. Please let me know if you see any "gaping" holes in my thot process. The airplane uses a Chelton dual screen EFIS with electric instrument backup. There is no vacuum system. Thanks for your time and any help is appreciated. Alan


    Message 6


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    Time: 07:06:48 PM PST US
    From: Tim & Diane Shankland <tshank@core.com>
    Subject: Re: Zener Diodes and LEDs
    --> AeroElectric-List message posted by: Tim & Diane Shankland <tshank@core.com> Yes you can use zeners but you need resistors also. What you want to do is to provide a stable voltage to drive the LED's so that the intensity does not change with the battery voltage. Using the example of three LED's each with a 1.7 volt drop connected in series with a desired current of 20 mA. With the three LED's connected in series and the cathode of the end one connected to ground connect the anode of the other end of the string to a 45 ohm resistor. Connect that resistor to a 320 ohm resistor, connect that resistor to battery voltage. Connect a 6 volt zener diode cathode to the junction of the two resistors. Connect the other end of the zener diode to ground. By the way I didn't check to see if these values are exactly available this is just an example. When operated at the minimum voltage of 12.4 volts at 20 mA the voltage drop across the 320 ohm resistor will be 6.4 volts leaving 6 volts across the zener diode which will not conduct. Now when operated the total voltage drop across the three LED's will be 5.1 volt leaving 0.9.volts across the 45 ohm resistor thus the current will be 20 mA. When the battery voltage rises to 13.8 volts the zener will conduct current causing an increased voltage drop across the 320 ohm resistor to maintain the voltage across it at 6 volts and the LED's will have a stable current source. Tim Shankland Malcolm Thomson wrote: >--> AeroElectric-List message posted by: "Malcolm Thomson" <mthomson@showmeproductions.com> > >Looks like this is what you need. See >http://www.periheliondesign.com/Vregflyer.htm > >Malcolm. > >-----Original Message----- >From: owner-aeroelectric-list-server@matronics.com >[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Dennis >Johnson >Sent: Sunday, March 05, 2006 4:49 PM >To: aeroelectric-list@matronics.com >Subject: AeroElectric-List: Zener Diodes and LEDs > > >--> AeroElectric-List message posted by: "Dennis Johnson" >--> <pinetownd@volcano.net> > >I'm making LED instrument floodlights and LED lights for an annunciator >panel. I expect the system voltage to vary between about 13.8 volts when >the engine and alternator are running, down to about 12.4 volts running just >off a lightly loaded battery. > >When connecting the LEDs in a series string of three, the resistance >required to get the voltage to the recommended level for the LEDs at the >13.8 system voltage is different than when the system voltage is 12.4. >Although it doesn't make a huge difference in the amount of light that comes >out of the LEDs, it is noticeable. > >I'm wondering (which often gets me into trouble) if I couldn't use zener >diodes instead of resistors to solve the problem of the light output >varying with system voltage. For example, if I have an array of three LEDs, >each with a Vf of 1.7 volts, could I use a 5.1 volt zener diode instead of >resistors? > >I don't have any experience with zener diodes, but the catalogs make it >sound like they produce a stable voltage output when operated within their >amperage limitations, sort of like a cheap power supply. Digikey sells them >for only a little more than resistors, so cost isn't an issue. Admittedly, >the varying light output isn't a huge problem, but if it's just as easy and >cheap to use zeners, why use resistors? > >Thanks, >Dennis Johnson >Lancair Legacy #257, wiring in (slow) progress > > > > > > > > >


    Message 7


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    Time: 07:20:54 PM PST US
    From: "Dennis Johnson" <pinetownd@volcano.net>
    Subject: Thanks for LED Help
    --> AeroElectric-List message posted by: "Dennis Johnson" <pinetownd@volcano.net> A big thanks to Brian Lloyd, Dan Beadle, Disk Tasker, and Malcom Thomson for their help teaching me how LEDs and zener diodes work! It is so gratifying to see so many people willing to share their expertise with a beginner. Thanks, guys! Best, Dennis Johnson Lancair Legacy (scrapping my LED wiring plan and starting from scratch) do not archive




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