---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 12/12/13: 9 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 09:49 AM - Re: Whelan capacitor substitute (Robert L. Nuckolls, III) 2. 11:04 AM - Switches Redux (Richard Reynolds) 3. 12:25 PM - Re: Switches Redux (Jeff Luckey) 4. 12:44 PM - Re: Switches Redux (Robert L. Nuckolls, III) 5. 01:32 PM - Re: Switches Redux (Robert L. Nuckolls, III) 6. 02:20 PM - Re: Switches Redux (Robert L. Nuckolls, III) 7. 02:23 PM - Re: Switches Redux (Jeff Luckey) 8. 02:46 PM - Speaking of physics . . . (Robert L. Nuckolls, III) 9. 03:27 PM - Re: Speaking of physics . . . (Sacha) ________________________________ Message 1 _____________________________________ Time: 09:49:07 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Whelan capacitor substitute > > >I "patched" in a couple of junkbox 470uF/450WVDC capacitors. Alas, >the power supply still does not work. Upon close examination I now >see some charred components and a swelled filter capacitor in the >low voltage section. Rather than make the huge effort to reverse >engineer and fix it, I think I'll buy a new Nova power supply for >under $100 and move on. > >Thanks for the idea, Bob. I'm attaching a picture of the HV >capacitors if for no other reason than to to satisfy peoples' curiosity. Under the circumstances, probably the most economical solution. If you have no plans for the carcass I'd like to have it. I'd pop for the packaging/postage. I've not had an opportunity to peer into the inner workings of this product for many moons. Bob . . . ________________________________ Message 2 _____________________________________ Time: 11:04:16 AM PST US From: Richard Reynolds Subject: AeroElectric-List: Switches Redux Bob, Application, RC model airplane, receiver-servos, 6V - 2100 mAh NiMH battery, 150 mA idle, 6A max intermittent. The battery is connected to the receiver-servos throughout an off-on switch (SPDT). Which switch is more reliable, mini toggle or a mini slide? For power (6A) (versus data), which contacts are more reliable, gold or silver? Both have a contact resistance of about 10 mOhms. Is any brand more reliable? A bad switch in flight will cause a bay day on the ground. Richard Reynolds B-47E 1/12 Scale Model Project ________________________________ Message 3 _____________________________________ Time: 12:25:37 PM PST US From: Jeff Luckey Subject: Re: AeroElectric-List: Switches Redux Richard,=0A=0AIt's been my experience that the slider type switch is more r eliable for R/C applications because it seems to be more resistant to high- frequency vibrations common in R/C aircraft.=0A=0AI asked the same question and went thru some analysis back in the 90's for some of my giant scale ae robatic ships and the consensus at that time was sliders were better for th is application.- I think that's why all radio manufacturers supply their systems w/ sliders.- I don't think that I've ever seen an after-market sw itch harness that was anything other than a slider.=0A=0A-Jeff=0A=0A=0A=0A_ _______________________________=0A From: Richard Reynolds =0ATo: AeroElectric AeroElectric =0ASent: Thursday, December 12, 2013 11:03 AM=0ASubject: AeroElectric-List: Switches Redux=0A =0A=0A=0ABob,=0A=0AApplication, RC model airplane, recei ver-servos, 6V - 2100 mAh NiMH battery, 150 mA idle, 6A max intermittent. =0A=0AThe battery is connected to the receiver-servos throughout an off-on switch (SPDT).=0A=0AWhich switch is more reliable, mini toggle or a mini sl ide?-=0A=0AFor power (6A) (versus data), which contacts are more reliable , gold or silver?-Both have a contact resistance of about 10 mOhms.=0A=0A Is any brand more reliable?=0A=0AA bad switch in flight will cause a bay da y on the ground.=0A=0ARichard Reynolds=0AB-47E 1/12 Scale Model Project ________________________________ Message 4 _____________________________________ Time: 12:44:40 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Switches Redux At 01:03 PM 12/12/2013, you wrote: Bob, Application, RC model airplane, receiver-servos, 6V - 2100 mAh NiMH battery, 150 mA idle, 6A max intermittent. The battery is connected to the receiver-servos throughout an off-on switch (SPDT). Which switch is more reliable, mini toggle or a mini slide? For power (6A) (versus data), which contacts are more reliable, gold or silver? Both have a contact resistance of about 10 mOhms. Is any brand more reliable? Richard, Are you aware of modelers who have lost an airplane due to failure of a receiver power source? In the pyramid of design requirements, what is the weakest link in your system wherein a failure becomes catastrophic? If you've identified the switch as a high-order concern, then 'reliability' of any mechanical device is probably driven more by environmental concerns than electrical ratings. What kinds of contaminants might get into the switch and degrade performance. Is vibration an issue? Gold contacts insure performance for contacts that need to work at very low current levels . . . levels too low to burn away contaminants on silver-cad contacts by virtue of arcing that occurs in normal operation. The silver-cad contacts are probably better suited to your task. If you want the ultimate in reliability, perhaps all solid state offers a solution. A high side switch biased to an ON-state with a Hall-effect switch. The Hall being magnetically excited by a "key" inserted to position a magnet. The 'works' for this switch would mount on an ECB about 1/2" x 3/4". It would take some mechanical fiddly-diddly to mount and integrate with the 'key'. Depending on the bounds of your worry and experiences of others, there's a constellation of approaches. A toggle is probably positionally more secure than a slide and is probably fitted with real silver-cad contacts as opposed to un-plated brass innards common to slide switches. Sorry not to have a definitive response but I'm sure that there are means for addressing your worst concerns. Bob . . . ________________________________ Message 5 _____________________________________ Time: 01:32:38 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Switches Redux At 02:24 PM 12/12/2013, you wrote: Richard, It's been my experience that the slider type switch is more reliable for R/C applications because it seems to be more resistant to high-frequency vibrations common in R/C aircraft. I asked the same question and went thru some analysis back in the 90's for some of my giant scale aerobatic ships and the consensus at that time was sliders were better for this application. I think that's why all radio manufacturers supply their systems w/ sliders. I don't think that I've ever seen an after-market switch harness that was anything other than a slider. -Jeff It would be interesting to know the physics behind any assertions for superior vibration resistance in a slide switch. It kinda argues with what we know about the construction of the two technologies. The moving contact in a slider is generally forced against stationary contacts by a compression spring centered on the moving contact. This means that vibration normal to the plane of the stationary contacts would work on the center of gravity for the moving contact directly against the spring pressure. It follows that when acceleration exceeds slider mass x force . . . Sir Isaac's Second law . . . discontinuities in the switch can be expected. In a toggle switch, the moving contact is a "teeter-totter" who's cg is located on the pivot of the mechanism. A spring presses the teeter-totter down against a stationary contact to one or the other side of the pivot to effect the switching behavior. Acceleration of the switch assembly normal to the plane of the stationary contacts once again acts on the c.g. of the moving contact which is located at the center . . . and balanced by equal masses on both sides of the pivot. The switch actuator spring adds a force on the 'closed' side of the switch, a force which, by virtue of that balance, is not opposed by the forces of acceleration. See http://tinyurl.com/noo8odx I'm having trouble visualizing how a toggle could be more prone to vibration induced disconnect. You have to get into mil-spec switches before the manufacturer's even offer much in the way of vibration data. The few switches I found with vibration ratings on their data sheets only spoke to effect of less than 100Hz . . . I'm wondering what is meant by 'high frequency' vibration characteristic of model airplanes. It's true that slide switches have been VERY popular with the R/C crowd . . . that's the only style of switch I observed on the rudder-only models of my youth. But then, that was long before the miniature toggle switch even came along. I'm not perceiving any foundation in physics for giving points to slide switches in the vibration game. I've yet to find any manufacturer's data that offers a comparison of vibration effects beyond that which I've hypothesized above. Bob . . . ________________________________ Message 6 _____________________________________ Time: 02:20:45 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Switches Redux oops!!!! When Acceleration exceeds spring force/slider mass . . . Sir Isaac's Second law . . . discontinuities in the switch can be expected . . . sorry Sir Isaac! Bob . . . ________________________________ Message 7 _____________________________________ Time: 02:23:55 PM PST US From: Jeff Luckey Subject: Re: AeroElectric-List: Switches Redux I dunno Bob, it's just the way they've done it for the past 40+ years. =0A=0A=0A=0A________________________________=0A From: "Robert L. Nuckolls , III" =0ATo: aeroelectric-list@matronics.co m =0ASent: Thursday, December 12, 2013 1:31 PM=0ASubject: Re: AeroElectric- ert L. Nuckolls, III" =0A=0AAt 02:24 PM 12/1 2/2013, you wrote:=0ARichard,=0A=0AIt's been my experience that the slider type switch is more reliable for R/C applications because it seems to be mo re resistant to high-frequency vibrations common in R/C aircraft.=0A=0AI as ked the same question and went thru some analysis back in the 90's for some of my giant scale aerobatic ships and the consensus at that time was slide rs were better for this application.- I think that's why all radio manufa cturers supply their systems w/ sliders.- I don't think that I've ever se en an after-market switch harness that was anything other than a slider.=0A =0A-Jeff=0A=0A- It would be interesting to know the physics=0A- behin d any assertions for superior vibration=0A- resistance in a slide switch . It kinda argues=0A- with what we know about the construction of=0A- the two technologies.=0A=0A- The moving contact in a slider is generall y=0A- forced against stationary contacts by a=0A- compression spring centered on the moving=0A- contact. This means that vibration normal=0A - to the plane of the stationary contacts=0A- would work on the cente r of gravity for the=0A- moving contact directly against the spring=0A - pressure. It follows that when acceleration=0A- exceeds slider mass x force . . . Sir Isaac's=0A- Second law . . . discontinuities in the s witch=0A- can be expected.=0A=0A- In a toggle switch, the moving cont act is a=0A- "teeter-totter" who's cg is located on the=0A- pivot of the mechanism. A spring presses the=0A- teeter-totter down against a sta tionary contact=0A- to one or the other side of the pivot to=0A- effe ct the switching behavior.=0A=0A- Acceleration of the switch assembly no rmal=0A- to the plane of the stationary contacts once=0A- again acts on the c.g. of the moving contact=0A- which is located at the center . . . and balanced=0A- by equal masses on both sides of the pivot.=0A- T he switch actuator spring adds a force on=0A- the 'closed' side of the s witch, a force which,=0A- by virtue of that balance, is not opposed by =0A- the forces of acceleration.=0A=0A- See http://tinyurl.com/noo8od x=0A=0A- I'm having trouble visualizing how a toggle=0A- could be mor e prone to vibration induced=0A- disconnect. You have to get into mil-sp ec=0A- switches before the manufacturer's even offer=0A- much in the way of vibration data. The few=0A- switches I found with vibration ratin gs on=0A- their data sheets only spoke to effect of=0A- less than 100 Hz . . .=0A=0A- I'm wondering what is meant by 'high frequency'=0A- v ibration characteristic of model airplanes.=0A- It's true that slide swi tches have been=0A- VERY popular with the R/C crowd . . . that's=0A- the only style of switch I observed on the=0A- rudder-only models of my youth. But then,=0A- that was long before the miniature toggle switch=0A - even came along.=0A=0A- I'm not perceiving any foundation in physic s=0A- for giving points to slide switches in the=0A- vibration game. I've yet to find any manufacturer's=0A- data that offers a comparison of vibration=0A- effects beyond that which I've hypothesized=0A- above. =========================0A ===================== ________________________________ Message 8 _____________________________________ Time: 02:46:49 PM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Speaking of physics . . . Last week I had occasion to refer a colleague to a series of videos available from MIT on their website at http://ocw.mit.edu In particular the lectures offered by Walter Lewin on various topics in physics. Highly recommended for anyone interested in a refresher . . . or grandparents hoping to plant the seeds of interests in grandchildren. Bob . . . ________________________________ Message 9 _____________________________________ Time: 03:27:16 PM PST US Subject: Re: AeroElectric-List: Speaking of physics . . . From: Sacha Hi Bob Any particular one which is relevant to aero electrics? There are 567 hits for Walter Lewin lectures on the site... Sacha On Dec 12, 2013, at 23:45, "Robert L. Nuckolls, III" wrote: > > Last week I had occasion to refer a colleague to > a series of videos available from MIT on their > website at http://ocw.mit.edu > > In particular the lectures offered by Walter Lewin > on various topics in physics. Highly recommended > for anyone interested in a refresher . . . or grandparents > hoping to plant the seeds of interests in > grandchildren. > > > > Bob . . . > > > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.