---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sun 12/28/08: 15 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 12:20 AM - CBA II Thermal Analysis - Does the CBA run too hot? (CamLight) 2. 06:44 AM - Re: Anything wrong with using a plier style crimper? (Robert L. Nuckolls, III) 3. 06:54 AM - Re: Re: D-Sub Pins (Robert L. Nuckolls, III) 4. 07:13 AM - Re: CBA-II Battery Tester modifications/improvements? (Robert L. Nuckolls, III) 5. 01:14 PM - Twisted Wires vs. Parallel (Dennis Johnson) 6. 02:12 PM - Re: Twisted Wires vs. Parallel (Bruce Bell) 7. 02:43 PM - Re: Twisted Wires vs. Parallel (CamLight) 8. 04:06 PM - Re: Twisted Wires vs. Parallel (Robert L. Nuckolls, III) 9. 04:08 PM - Re: Re: Twisted Wires vs. Parallel (Robert L. Nuckolls, III) 10. 07:19 PM - Re: Twisted Wires vs. Parallel (S. Ramirez) 11. 09:56 PM - Pitts S1 Wiring Diagram (Stuart Mackereth) 12. 10:48 PM - Re: Pitts S1 Wiring Diagram (John Cleary) 13. 11:05 PM - Re: Pitts S1 Wiring Diagram (Stuart Mackereth) 14. 11:30 PM - Re: CBA-II Battery Tester modifications/improvements? (CamLight) 15. 11:34 PM - Re: Twisted Wires vs. Parallel (CamLight) ________________________________ Message 1 _____________________________________ Time: 12:20:20 AM PST US Subject: AeroElectric-List: CBA II Thermal Analysis - Does the CBA run too hot? From: "CamLight" Hello all, After hearing of several of them burning out, I did an analysis of two West Mountain Radio CBA II's and have written it up: http://www.camlight.com/techinfo/CamLight_Systems_CBA_II_Thermal_Analysis.pdf Bob wrote up a really great analysis back in 2005 (which is still being passed around) but a couple of my conclusions differ from those Bob made so I wanted to post here to discuss them. Those conclusions are: - The MOSFETs in the CBA and the 10x Amplifier are not rated for use as a load and are subject to failure at levels significantly below the CBA's 100W rating. This includes the IRFP2907. - Paralleling switching MOSFETs is very, very problematic and each should be driven by its own local control loop. - Due to overheating, the CBA should not be used at a level above 65W for long term reliability. Never exceed 86W to prevent failure of the MOSFET. - Discharging packs at above 20V (and perhaps even lower) significantly increases the risk of the CBA burning out, at almost any power level. A fun note... After reading Bob's analysis a couple of times, I suddenly noticed that he uses the exact same graphics to represent/model the thermal resistances of a MOSFET that I've always used. Important? No. But it was fun to realize why it was such easy reading for me. :-) -------- John M. Owner CamLight Systems Read this topic online here: http://forums.matronics.com/viewtopic.php?p=221447#221447 ________________________________ Message 2 _____________________________________ Time: 06:44:41 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Anything wrong with using a plier style crimper? At 10:38 PM 12/27/2008, you wrote: >I rounded up some ratcheting style crimping tools from airport folk >and a homebuilder for crimping Red crimp on connectors from Stein >(fast on and ring). > >Got hold of a Paladin tool with several sets of dies, and some no >name non adjustable tool. > >The die sets for the Paladine: >****Part number said for insulated terminals and had 3 colored dots >including red >****There was a set of dies with no part number but fit tool >(perhaps from Stein??) and looked like for insulated terminals >And a few others, one for uninsulated terminals and other > >First off no matter what the adjustment, if using 22 gauge wire, >even with the dies completely bottomed, could not get as much a grip >as i would like. I could semi make it better by splicing more wire >and doubling it over to better fill hole. Problem was it still did >not crimp wire terrific and the portion that was to crimp on the >insulation for strain relief was too far away (too wide a die?) >where it was only partially catching the metal in the terminals. All >the terminals from Stein and Terminal Town and Mcmaster (double >metal) appeared to be too short for tool. I tried all the dies I had >and combinations. Not great success with the no name tool with fixed >dies and is non adjustable. > >I could get an OK crimp, probably will work and with heat shrink >support will probably be OK, but insulation was not captured >properly and if i sliced open the crimp on the wire, you could see >it is not as compact as would be nice. > >Then I pulled out an old and rusty Whitaker WC2850 tool, looks like >a pair of pliers with several dies on it. > >After some practice I can make what I think is a very nice crimp, >far better than what I could do with the other tools. > >*First I stripped twice what I need and double up tail to go into terminal >*Then crimp with RARB die about 1/16" from the edge of terminal >*Then use a part of tool called "A" which is kind of a half cylinder >(feel here is important) and put a dimple on top of terminal where I >just crimped. I tried to over crimp this step and if I go crazy >where terminal in stead of being straight begins to bend, I can tear >wire when pulled very hard because wire is mashed too much. I am >pretty confident can repeat this dimple consistently. When I sliced >practice terminals apart had a very compacted crimp without strands >being deformed/mashed. Without dimple, crimp is acceptable in my >mind for automobiles only, and places easy to get at with no moisture present. >*Then use RARB to crimp wire insulation about 1/16" from edge, no >hurting of insulation at all and wire is held pretty good. > >Anyone see any problems crimping like I describe? i could have >stripped and crimped a dozen terminals in time it took me to write this. > >Ron Parigoris The physics for making a gas-tight connection between wire and terminal is process-sensitive. The "ideal" crimped junction puts sufficient force on the terminal to close the cross-section of terminal and wire copper just to the point that the terminal and wire strands become one piece of metal. Too little mash, and voids in the joint allow oxygen laden moisture to enter raising risk of failure due to corrosion. Too much mash and strength of the strands is weakened by reduction of cross-section thus raising risk of failure under tension/vibration. See: http://aeroelectric.com/articles/CrimpTools/crimptools.html Dimple-crimps are for terminals going onto solid wire only. See "Solistrand" terminals and tooling from AMP. You will note that all crimp tools suggested and/or evaluated in our writing are free of "dimple" punches. The PIDG style terminal is best applied with uniform pressure offered by smooth bore dies. Of secondary concern is molding of the wire-grip to the conductor just outside the joint. The terminal may have too little volume in the closed condition for the amount of plastic in the terminal's wire support insulation. See: http://aeroelectric.com/Pictures/Terminals/JST_Samples_2.jpg These terminals were electrically okay when installed with our favorite tools . . . but did not become part of our inventory because we had no tools that would do a professional looking installation. Ron, it's not possible to encourage or discourage use of the tools you've cited without making a first-hand evaluation of their performance under the guide-lines discussed in the article above and these additional pieces found on my website . . . http://aeroelectric.com/articles/faston3.pdf http://aeroelectric.com/articles/terminal.pdf Finally, on the subject of wire-joining, I'll remind readers of this article published some years back in Sport Aviation. The author didn't have a clue about simple-ideas for the processes in which he claimed considerable knowledged and skill. http://aeroelectric.com/articles/rules/review.html Bob . . . ________________________________ Message 3 _____________________________________ Time: 06:54:01 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: D-Sub Pins At 06:55 PM 12/27/2008, you wrote: > > >Bob: > >Looking thru your archives, I see that one can use D-Sub's are wiring >connections: I.E. - joining 2 wires together, rather than use butt splices, >solder seal, etc.... >So my question is: > >1- Rather than soldering my Mic & Phone jack wires directly to my jack >outlets, can I solder leads, then use D-Sub pins to join to the leads to the >amin wires? If you wish. What is the advantage? You've increased parts count and total numbers of joints. Are these jacks likely to be removed and replaced as part of a maintenance activity? If you need to break a wire bundle during routine maintenance then it's best to use a complete mated pair of d-sub connectors as opposed to individual pin-pairs under heatshrink. >2- Can I also use these D-Subs for splicing shielded wire: 22 awg wire? > >I can see al lot of uses for these D-subs, amazing !!! They ARE a legacy technology with features that can address design-goals that are peripheral to or sub-sets of the original ideas. But as a general rule we try to MINIMIZE parts count and $time$ to install wires for best reliability and lowest cost of ownership. Splicing of wires is best made with permanent joining technologies (crimp/solder) unless there is an over-riding interest in future maintenance activities made simple by the use of de-mateable splices whether grouped as connectors or individual pins. Keep in mind too that the single pin-pairs under heat-shrink are VERY vulnerable to de-mating under tension. Use this technique with careful attention to support of strands either side of the splice to prevent tugging on the joint. Bob . . . ----------------------------------------) ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------- ________________________________ Message 4 _____________________________________ Time: 07:13:21 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Re: CBA-II Battery Tester modifications/improvements? > >I think that's an idea worth exploring! >I've developed a 500W (400W continuous) electronic load that can be >used to extend the capabilities of any analyzer or discharger >(http://www.rcgroups.com/forums/showthread.php?t=938266) but there's >a real need for "host" software and a load in the power range of the >CBA, perhaps 100W-200W. This would be perfect for most DIY'ers and >could easily be paralleled for higher power handling. > >The software would have to be very graphics-capable as the plotting >and graphing features would be extremely important. I'd love to see >it not require a huge installation just to run. But, the options >may be limited. I'm not so sure about the graphics. Yes, they do make for an effective display of data . . . and comparison of similar batteries . . . http://aeroelectric.com/articles/AA_Bat_Test.pdf The data for this article was taken with a one-sample-per-second data acquisition module that produces columnar data easily imported into graphics applications like autocad and excel. For the purpose of writing articles, the graphics offered by WestMountainRadio are pretty . . . http://www.aeroelectric.com/Pictures/Curves/9vBatteryTests.jpg but from an engineering perspective, a numerical value for energy delivered under the prescribed test conditions is quite sufficient. The results of dynamic tests for evaluating battery source impedance could be offered out as numerical values. I did a flight test program for Raytheon a few years back where the Weeder Technology modules proved quite useful. http://www.weedtech.com/ http://aeroelectric.com/Pictures/Tools/Test_Equipment/Data_Acquisition/Weedtech_DAS_2.jpg As a first pass for crafting a more robust version of the CBA-II, a Weeder analog input module for $69 and an analog output module for $99 would offer 95% of the hardware to implement the task. Very simple programs in any language of choice could be crafted to orchestrate the testing, gathering of data values and presentation of end-point results with no graphics capabilities at all. One could also store individual data points on the hard drive in a format easily imported to Excel. >The CBA software has a nice light footprint though. An executable, >help file, settings file, three DLLs for USB comms and forms >handling. It may have some registry keys or other files in public >directories but it doesn't seem to require the NET >framework. MileHighWings' eFlightWatt logger had a single >executable file that did everything, no installation >needed. Something like this for an open source tester would be terrific. Sure. And I wouldn't discourage any interested parties from turning their vision into really nifty applications by exercising their programming skills. From the hands-on engineering perspective, my personal needs for battery testing can be easily addressed with more rudimentary software. In fact, I still keep 20 year old copies of Turbo-Basic that outputs compiled .exe files for talking/listening to the Weeder modules. I have a supply of these guys on the shelf from various programs over the years. They still offer the hammer-n-nails approach to crafting a quick and useful test-setup. Bob . . . ________________________________ Message 5 _____________________________________ Time: 01:14:19 PM PST US From: "Dennis Johnson" Subject: AeroElectric-List: Twisted Wires vs. Parallel We often see instructions to twist the positive and negative wires together to reduce noise problems. Instructions from B&C for their voltage regulator even specified the number of twists per inch. But I'm wondering about the physics. From studying the 'Connection, it seems that paralleling the positive and negative wires tightly together would have the same effect as twisting them together. Is twisting the wires together recommended because it is a convenient way to keep the wires in close contact? Or is there something about the nature of the electromagnetic fields that makes twisting more effective? Thanks, Dennis Legacy, 220 hours, mostly twisted positive and negative wires ________________________________ Message 6 _____________________________________ Time: 02:12:46 PM PST US From: " Bruce Bell" Subject: Re: AeroElectric-List: Twisted Wires vs. Parallel Hi All, Years ago I replaced the windshield on my A35 Bonanza and found the wires to the Mag compass light twisted. This was done by the beech factory. Must be something to it! Regards, Bruce Bell RV-4, N23BB, B&C Alternator and starter. All wiring to Aeroelectric Specs. No smoke! DO NOT ARCHIVE! ----- Original Message ----- From: Dennis Johnson To: aeroelectric-list@matronics.com Sent: Sunday, December 28, 2008 11:28 AM Subject: AeroElectric-List: Twisted Wires vs. Parallel We often see instructions to twist the positive and negative wires together to reduce noise problems. Instructions from B&C for their voltage regulator even specified the number of twists per inch. But I'm wondering about the physics. From studying the 'Connection, it seems that paralleling the positive and negative wires tightly together would have the same effect as twisting them together. Is twisting the wires together recommended because it is a convenient way to keep the wires in close contact? Or is there something about the nature of the electromagnetic fields that makes twisting more effective? Thanks, Dennis Legacy, 220 hours, mostly twisted positive and negative wires ________________________________ Message 7 _____________________________________ Time: 02:43:48 PM PST US Subject: AeroElectric-List: Re: Twisted Wires vs. Parallel From: "CamLight" Twisting reduces the wiring's susceptibility to interference due to the way it can cancel out certain external signals by reducing the wire's loop area (which reduces its degree of coupling to the interference). It also reduces crosstalk between nearby pairs of wire, but you need different twist rates for each pair to minimize coupling between them. What I'm not sure of is the difference in effectiveness between pairs carrying single-ended signals (signal and ground) vs. differential signals (signal+ and signal-. used in telecomm and computer equipment). -------- John M. Owner CamLight Systems Read this topic online here: http://forums.matronics.com/viewtopic.php?p=221507#221507 ________________________________ Message 8 _____________________________________ Time: 04:06:51 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Twisted Wires vs. Parallel >We often see instructions to twist the positive and negative wires >together to reduce noise problems. Instructions from B&C for their >voltage regulator even specified the number of twists per inch. > >But I'm wondering about the physics. From studying the 'Connection, >it seems that paralleling the positive and negative wires tightly >together would have the same effect as twisting them together. Is >twisting the wires together recommended because it is a convenient >way to keep the wires in close contact? Or is there something about >the nature of the electromagnetic fields that makes twisting more effective? A single conductor in relatively "free" space has some behaviors of an antenna. I.e, it can radiate as well as gather some portion of any electro-magnetic energy in the vicinity. When electrons move relative to some local point one can measure both an electric (electro-static) force as well as a magnetic (electro-magnetic) force as a result of that motion. For example, a beam of electrons shot from the rear of a cathode ray tube toward a screen can be deflected or pointed because we can exploit EITHER the electro-static or electro-magnetic properties of a moving stream of electrons. It matters not whether those electrons move through a conductor or through a vacuum. In a CRT television display http://aeroelectric.com/Pictures/Misc/Electro-Magnetic_Deflection.jpg electro-magnets on the neck of the tube were used to control direction of the electron beam to produce spots of light over the surface of the screen. In an oscilloscope, electro-static deflection . . . . http://aeroelectric.com/Pictures/Misc/Electro-Static_Deflection.jpg . . . was preferred for its much higher frequency response. Not only can electron streams be magnetically and statically influenced as described above, they exert their own, similar influences. Suppose we start with a circular loop of wire say 10' in diameter. This is an excellent example of a loop antenna with an ability to efficiently radiate or intercept energy at some frequency. Now, let's squash the loop in one dimension. As it moves toward an elliptical shape, the AREA of the loop goes down and the radiation/reception efficiency goes down. The obvious end point happens when the area approaches zero and the circle becomes a parallel pair of wires. It's intuitively obvious that electrons flowing in one wire are exactly balanced by opposite direction flow in the opposite wire thus cancelling their individual electro-magnetic and electro-static effects . . . mostly. At higher frequencies it can be shown that parallel lines do not exactly cancel mutual magnetic effects because of the non-zero distance between their centers. Here it becomes valuable to twist the two conductors such that what ever leakage exists perpendicular to the conductors tends to be washed out by the reverse polarity of effects longitudinally displaced 1/2 twist away. Another very effective technique is to use shielded wire. Use the center conductor for the outbound electron flow and the shield for the inbound flow. Here the two fields ARE centered on each other and cancel each other exactly. In the case of the compass light wire, the goal is to null the magnetic field around a wire that MUST be positioned in close proximity to the system most vulnerable to interference from variable and stray magnetic fields. Some manufacturers twisted their outbound and return wires. Others ran the wire up a small i.d. copper tube to make inbound/outbound paths. Similarly, shielded wire would be equally effective in this regard. Twisting the B&C Alternator wires was done at my suggestion back when plastic and glass canard pushers were king. The effects of poorly managed inbound/outbound conductor pairs had some profound effects on compass as well as audio systems. But again, this practice IS NOT generally recommended for ALL inbound/outbound pairs in an airplane. Like my oft repeated admonition for "follow the manufacturer's instructions" for shielding practices, the same advice applies to things like twisting for PM alternator installations in plastic airplanes and compass lights. Twisting makes a wire bundle more bulky and more $time$ consuming to fabricate and install. Bob . . . ________________________________ Message 9 _____________________________________ Time: 04:08:23 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Twisted Wires vs. Parallel At 04:41 PM 12/28/2008, you wrote: > >Twisting reduces the wiring's susceptibility to interference due to >the way it can cancel out certain external signals by reducing the >wire's loop area (which reduces its degree of coupling to the >interference). It also reduces crosstalk between nearby pairs of >wire, but you need different twist rates for each pair to minimize >coupling between them. > >What I'm not sure of is the difference in effectiveness between >pairs carrying single-ended signals (signal and ground) vs. >differential signals (signal+ and signal-. used in telecomm and >computer equipment). Paralleled or twisted conductors get you benefit only when they carry equal magnitude and opposite polarity signals. This is why RS232 single-ended data was quickly replaced by RS422 twisted pairs under shields for the greatest noise immunity. Bob . . . ----------------------------------------) ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------- ________________________________ Message 10 ____________________________________ Time: 07:19:13 PM PST US From: "S. Ramirez" Subject: RE: AeroElectric-List: Twisted Wires vs. Parallel Dennis, There is no difference electrically between two wires that are kept at the same distance in parallel and two wires that are twisted together to stay parallel. The reason they are twisted together is that it is the simplest way to keep them in parallel while the cable (a combination of wires, shields, insulation, etc.) bends and distorts. When an RS-422 transmitter generates a signal, it has two circuits that drive the twisted wire pair. One circuit sources current, while the other circuit sinks current. When a differential twist wire pair carries two currents from the transmitter to the receiver, they travel from the source driver to the load (a termination resistor next to the receiver), then back to the current sink. Along each wire, the current generates an electromagnetic field defined by the right hand rule, where the direction of the field is per the direction of the hand's fingers when the thumb is pointing toward the direction of current flow. Since the current in one wire is traveling opposite the current in the other wire, the fields oppose each other and ideally cancel each other out. They also ideally cause no noise to be radiated. Perhaps the greatest benefit of RS-422 and differential signaling is immunity from external noise in the receiver. RS-422 receivers are built to reject "common-mode noise, which is noise that is of the same amplitude on both the + and - terminals of the receiver. This is where the twisted wire pair comes in. It connects to the receiver's + and - terminals and brings in both the real signal and common-mode noise. While the twisted-wire pair is shielded, some noise will leak in, but the electromagnetic and electrostatic fields will cut across wires at the same amplitude, because the wires are so close together. Thus, the noise's amplitude will appear at the receiver's + and - terminals equally and will be rejected by the receiver, since it is designed to reject common-mode noise. As an example, the AM26LV32 is a commonly used differential line 3.3V receiver. It has a common mode input voltage range from -0.3 to 5.5V and will reject any voltage that appears on both terminals in this range. The voltages on its terminals must have a delta of greater than 0.2V for it to change its outputs. You probably have to be involved in the measurement of real world signals and problems to appreciate just how good the AM26LV32 works to reject common-mode noise. One of the things that I haven't mentioned is that the termination resistor not only serves to terminate the twisted wire pair's characteristic impedance but also provides a low impedance to prevent electrostatic and electromagnetic fields from developing high voltages in twisted wire pairs. So to reiterate, there is nothing magical about twisted wire pairs other than they keep the wires in close proximity to each other and that's it. Everything else I said above is just fluff! :) Simon Ramirez Copyright 2008 From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Dennis Johnson Sent: Sunday, December 28, 2008 12:29 PM Subject: AeroElectric-List: Twisted Wires vs. Parallel We often see instructions to twist the positive and negative wires together to reduce noise problems. Instructions from B&C for their voltage regulator even specified the number of twists per inch. But I'm wondering about the physics. From studying the 'Connection, it seems that paralleling the positive and negative wires tightly together would have the same effect as twisting them together. Is twisting the wires together recommended because it is a convenient way to keep the wires in close contact? Or is there something about the nature of the electromagnetic fields that makes twisting more effective? Thanks, Dennis Legacy, 220 hours, mostly twisted positive and negative wires ________________________________ Message 11 ____________________________________ Time: 09:56:30 PM PST US From: "Stuart Mackereth" Subject: AeroElectric-List: Pitts S1 Wiring Diagram Hi all.. been trawling through all the posting history on this list looking for some help with what layout and equipment set make sense in the tight engine compartment of a Pitts S1. Sorry if any of this is repeat/old stuff, but it's all new to me. Thanks also to Bob who has given me many hours of enjoyment trying to get to grips with his manual, and Z figures. I started on Z13/8 and pulled out the 2nd big alternator in favor of a single small SD-8 one, and have gone from there. A Pitts should be rather simple, I would have thought. This is a VFR short-hop plane 99% of the time, doing aerobatics I had a good look at the aerobatic wiring diagram from B&C... so I had assumed I could get by on a SD-8 alternator as only electrical generation source. I have a Icom A200, Narco Xpdr, Encoder and the usual engine instruments (EGT, CHT, OILT, OILP, FUELP) so thought I could get away it. Um, ok, also a Fuel boost pump (only during starting) and smoke pump (couple of minutes a flight)... I also would like to run a AV80R GPS as well, if possible. Now I'm wondering about the SD-8... and if not, well, then the SD-20. I can add up all the Amp loads on each thing, but I'm not sure how much under/over capacity I need to run everything? Is there a general rule of thumb? My other question is whether there is enough space behind the engine for the vacuum mounted SD-8 - considering I'm planning dual PMAGS, and have an inverted OIL kit right there in the same place. A friend building an S1 that I talk to a lot as opted for the PlanePower 60Amp unit that is belt driven up front to free up some space, as he reckoned it was too tight. Would love a second opinion from someone with an S1. Most S1's flying out there are 20, 30 years old, even older, and I'm hoping someone can help me take advantage of the new technology advances to build a simple, clean and lightweight electrical system. Thanks to anyone who can help. ________________________________ Message 12 ____________________________________ Time: 10:48:33 PM PST US From: "John Cleary" Subject: RE: AeroElectric-List: Pitts S1 Wiring Diagram Hello Stuart, I have an S1 with an SD-8, standard slick mags and an inverted oil system. It is tight but doable. Cheers, John -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Stuart Mackereth Sent: Monday, 29 December 2008 4:53 PM Subject: AeroElectric-List: Pitts S1 Wiring Diagram --> Hi all.. been trawling through all the posting history on this list looking for some help with what layout and equipment set make sense in the tight engine compartment of a Pitts S1. Sorry if any of this is repeat/old stuff, but it's all new to me. Thanks also to Bob who has given me many hours of enjoyment trying to get to grips with his manual, and Z figures. I started on Z13/8 and pulled out the 2nd big alternator in favor of a single small SD-8 one, and have gone from there. A Pitts should be rather simple, I would have thought. This is a VFR short-hop plane 99% of the time, doing aerobatics I had a good look at the aerobatic wiring diagram from B&C... so I had assumed I could get by on a SD-8 alternator as only electrical generation source. I have a Icom A200, Narco Xpdr, Encoder and the usual engine instruments (EGT, CHT, OILT, OILP, FUELP) so thought I could get away it. Um, ok, also a Fuel boost pump (only during starting) and smoke pump (couple of minutes a flight)... I also would like to run a AV80R GPS as well, if possible. Now I'm wondering about the SD-8... and if not, well, then the SD-20. I can add up all the Amp loads on each thing, but I'm not sure how much under/over capacity I need to run everything? Is there a general rule of thumb? My other question is whether there is enough space behind the engine for the vacuum mounted SD-8 - considering I'm planning dual PMAGS, and have an inverted OIL kit right there in the same place. A friend building an S1 that I talk to a lot as opted for the PlanePower 60Amp unit that is belt driven up front to free up some space, as he reckoned it was too tight. Would love a second opinion from someone with an S1. Most S1's flying out there are 20, 30 years old, even older, and I'm hoping someone can help me take advantage of the new technology advances to build a simple, clean and lightweight electrical system. Thanks to anyone who can help. ________________________________ Message 13 ____________________________________ Time: 11:05:05 PM PST US From: "Stuart Mackereth" Subject: RE: AeroElectric-List: Pitts S1 Wiring Diagram Great, thanks John. What line up do you run - VHF, XPDR, GPS, etc? Don't suppose you have a picture of the back for me to have a look at? Sorry, but now you got me started ;-) -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of John Cleary Sent: Monday, 29 December 2008 7:40 p.m. Subject: RE: AeroElectric-List: Pitts S1 Wiring Diagram --> Hello Stuart, I have an S1 with an SD-8, standard slick mags and an inverted oil system. It is tight but doable. Cheers, John -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Stuart Mackereth Sent: Monday, 29 December 2008 4:53 PM Subject: AeroElectric-List: Pitts S1 Wiring Diagram --> Hi all.. been trawling through all the posting history on this list looking for some help with what layout and equipment set make sense in the tight engine compartment of a Pitts S1. Sorry if any of this is repeat/old stuff, but it's all new to me. Thanks also to Bob who has given me many hours of enjoyment trying to get to grips with his manual, and Z figures. I started on Z13/8 and pulled out the 2nd big alternator in favor of a single small SD-8 one, and have gone from there. A Pitts should be rather simple, I would have thought. This is a VFR short-hop plane 99% of the time, doing aerobatics I had a good look at the aerobatic wiring diagram from B&C... so I had assumed I could get by on a SD-8 alternator as only electrical generation source. I have a Icom A200, Narco Xpdr, Encoder and the usual engine instruments (EGT, CHT, OILT, OILP, FUELP) so thought I could get away it. Um, ok, also a Fuel boost pump (only during starting) and smoke pump (couple of minutes a flight)... I also would like to run a AV80R GPS as well, if possible. Now I'm wondering about the SD-8... and if not, well, then the SD-20. I can add up all the Amp loads on each thing, but I'm not sure how much under/over capacity I need to run everything? Is there a general rule of thumb? My other question is whether there is enough space behind the engine for the vacuum mounted SD-8 - considering I'm planning dual PMAGS, and have an inverted OIL kit right there in the same place. A friend building an S1 that I talk to a lot as opted for the PlanePower 60Amp unit that is belt driven up front to free up some space, as he reckoned it was too tight. Would love a second opinion from someone with an S1. Most S1's flying out there are 20, 30 years old, even older, and I'm hoping someone can help me take advantage of the new technology advances to build a simple, clean and lightweight electrical system. Thanks to anyone who can help. Checked by AVG - http://www.avg.com 2:23 p.m. ________________________________ Message 14 ____________________________________ Time: 11:30:42 PM PST US Subject: AeroElectric-List: Re: CBA-II Battery Tester modifications/improvements? From: "CamLight" nuckolls.bob(at)aeroelect wrote: > I'm not so sure about the graphics. Yes, they do make for an > effective display of data . . . and comparison of similar > batteries . . . > > http://aeroelectric.com/articles/AA_Bat_Test.pdf > > The data for this article was taken with a one-sample-per-second > data acquisition module that produces columnar data easily > imported into graphics applications like autocad and excel. > For the purpose of writing articles, the graphics offered by > WestMountainRadio are pretty . . . > > http://www.aeroelectric.com/Pictures/Curves/9vBatteryTests.jpg > > but from an engineering perspective, a numerical value for > energy delivered under the prescribed test conditions is > quite sufficient. The results of dynamic tests for evaluating > battery source impedance could be offered out as numerical > values. As someone involved heavily in engineering, I agree. But you'll find a lot of very strong opposition to devices that only output numerical values for later importing and graphing or for use in creating a table. These all take extra work to do and is considered a total PITA by those who don't revel in the numbers the way we do. In my opinion, the success of the CBA is in its software (and its price, of course). It allows for very, very easy and no-work testing and comparison of different cells. There are other devices out there that allow for exporting to Excel or other saving of data, but they aren't nearly as popular. As a first step, just storing the data for import into Excel is OK. Even for taking and creating tables with. But, it would be nice to see a growth path possible for the software to include on-screen graphing/plotting. There are many constant-current load circuits out there but they're not being built and used by very many people, I think the right software is what would make the difference. nuckolls.bob(at)aeroelect wrote: > > I did a flight test program for Raytheon a few years > back where the Weeder Technology modules proved quite > useful. > > http://www.weedtech.com/ > > http://aeroelectric.com/Pictures/Tools/Test_Equipment/Data_Acquisition/Weedtech_DAS_2.jpg > > As a first pass for crafting a more robust version of > the CBA-II, a Weeder analog input module for $69 and > an analog output module for $99 would offer 95% of > the hardware to implement the task. Very simple programs > in any language of choice could be crafted to orchestrate > the testing, gathering of data values and presentation > of end-point results with no graphics capabilities > at all. > > One could also store individual data points on the > hard drive in a format easily imported to Excel. > Those are nice units! I've been using the USB-6008 DAQ unit from National Instruments (http://sine.ni.com/nips/cds/view/p/lang/en/nid/14604) for various projects, which is competitively priced. It includes driver and basic logging software too. I'd have to check closer to make sure it can support what the project might need but it's worth checking out IMHO. Another option is one you alluded to earlier, a PIC. That would result in a very small and inexpensive unit to control the load with and acquire and upload the data from. Someone would have to develop and test the firmware though. There's still a decent amount of hardware left to work out though...PCB design and selection of the MOSFETs, op-amps, resistor/capacitors, voltage regulators, microprocessor, connectors, heat sink, fan, etc., for the load itself. nuckolls.bob(at)aeroelect wrote: > > Sure. And I wouldn't discourage any interested parties > from turning their vision into really nifty applications > by exercising their programming skills. From the hands-on > engineering perspective, my personal needs for battery > testing can be easily addressed with more rudimentary > software. > > In fact, I still keep 20 year old copies of > Turbo-Basic that outputs compiled .exe files > for talking/listening to the Weeder modules. > I have a supply of these guys on the shelf from > various programs over the years. They still > offer the hammer-n-nails approach to crafting > > a quick and useful test-setup. > > Bob . . . I remember Turbo-Basic. You're right, a very useful software package! :) I think you bring up a very good point. There will be two groups of users for this load. The ones who just need the raw data outputted in the simplest way possible and those who want it displayed in graphical form to allow for the quickest way to see what they need to see. -------- John M. Owner CamLight Systems Read this topic online here: http://forums.matronics.com/viewtopic.php?p=221572#221572 ________________________________ Message 15 ____________________________________ Time: 11:34:34 PM PST US Subject: AeroElectric-List: Re: Twisted Wires vs. Parallel From: "CamLight" simon(at)synchdes.com wrote: > There is no difference electrically between two wires that are kept at the same distance in parallel and two wires that are twisted together to stay parallel. The reason they are twisted together is that it is the simplest way to keep them in parallel while the cable (a combination of wires, shields, insulation, etc.) bends and distorts. But don't pairs in untwisted pair cabling suffer from more crosstalk and susceptibility to interference than in twisted-pair cabling? And, IIRC, can't you do a longer run with twisted-pair than with untwisted-pair cable? -------- John M. 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