---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sat 03/07/09: 9 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:27 AM - ACS's Lightsaver gadget (Ralph Finch) 2. 08:44 AM - grayhill rotary (Fergus Kyle) 3. 09:06 AM - Re: ACS's Lightsaver gadget (Vern Little) 4. 09:48 AM - Re: ACS's Lightsaver gadget (B Tomm) 5. 11:12 AM - Re: ACS's Lightsaver gadget (Richard E. Tasker) 6. 12:16 PM - Re: ACS's Lightsaver gadget (Vern Little) 7. 02:09 PM - one to multiple (Dan Ballin) 8. 04:05 PM - Re: ACS's Lightsaver gadget (Robert L. Nuckolls, III) 9. 04:20 PM - Re: ACS's Lightsaver gadget (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 08:27:47 AM PST US From: "Ralph Finch" Subject: AeroElectric-List: ACS's Lightsaver gadget Aircraft Spruce offers this gadget (http://www.aircraftspruce.com/catalog/elpages/lightsaver.php) to eliminate the large current inrush to a cold tungsten filament, thus supposedly greatly increasing lamp life. Sounds reasonable, but wonder what the experts think. And I'm curious why it has to be mounted on a heat-sink surface...does it consume lots of energy while the lamp is on? "WHY INSTALL A LIGHTSAVER Typical landing and taxi lights in aircraft utilize a lamp that has a tungsten filament. Tungsten, which is a special metal, produces relatively high efficiency white light when electrical current flows through it. Tungsten wire is wound between two electrodes within the lamp. Unfortunately the metal wire has an undesirable characteristic. The metal filament has an extremely low electrical resistance when the temperature of the tungsten filament is at ambient (25C). Once the lamp is turned on, the filament resistance changes from close to 0 ohms (dead short) to 1.5 ohms. An increase of approximately 100 times. The dead short condition causes a massive inrush of current for several mille seconds. A typical 100 watt 12 volt lamp which when on draws 8 to 9 amps may see 800-1000 amps for that split second depending on the charged condition of the aircrafts battery. This causes severe stress to the lamp filament, which over repeated on/off cycles results in a fracture (open) in the filament. This is why the failure of the lamp typically occurs at turn on. HOW A LIGHTSAVER WORKS The Lightsaver prevents this massive inrush allowing the filament to draw the rated current even at turn on with no change in typical light output performance. The filament life increases up to 10 times due to reducing the stress induced by inrush current. This is something the lamp manufacturers don't want you to know. After all they are in the business of manufacturing replacement lamps for your aircraft. HOW IS THE LIGHTSAVER INSTALLED INTO MY AIRCRAFT? The installation is simple. The Lightsaver is placed in series with the lamp on either the positive or negative side of the electrical interconnection. The Lightsaver must be mounted to a heat-conducting surface such as the firewall of the aircraft. Mounting is accomplished using screws and nuts to secure it to the firewall." ________________________________ Message 2 _____________________________________ Time: 08:44:05 AM PST US From: "Fergus Kyle" Subject: AeroElectric-List: grayhill rotary Bob, [And Ron] I tried the referred part no. and it seerms no longer to be in stock. I didn't try to research further (lazy)...... Ferg >I don't have much space (rotary switch?) is there such a thing as a >four pole, triple throw three position mini toggle switch with three >positions and 16 terminals? > >If so where can you get one? >I can make do with a 4 pole, double throw with center off but the 4PTT >would be "much more better" if such a thing exists. > >I want to control intensity of several different light sources to >achieve a "Day", "Night" and "Dark night" level of intensity. Since all >the light sources are different (one linear regulator would not cut >it), will choose resistors that are close to what I want, and fit mini >potentiometers to fine tune. A DPDT could have up "Day", down "Night" >and "Dark night" could use middle to turn everything off. A triple >throw would allow me to have 3 intensities. > >Thx. >Ron Parigoris Grayhill #51PT30-01-4-03N http://tinyurl.com/bsws4r Bob . . . ________________________________ Message 3 _____________________________________ Time: 09:06:05 AM PST US From: "Vern Little" Subject: Re: AeroElectric-List: ACS's Lightsaver gadget These devices look like standard power resistors available from Digikey and others. What I use are inrush current limiters (also from Digikey) that have a negative temperature coefficient so that they have a high resistance when cold, but a low resistance when warm. See http://search.digikey.com/scripts/dksearch/dksus.dll?Detail&name=KC023L-ND These are the ones I used for my 75W halogen lamps. The only side-effect may be that a wig-wag flasher may need to be modified to slow down the flashing rate to ensure maximum lamp brightness during operation. I believe that they are better than resistors in this application. Cheers Vern Little ----- Original Message ----- From: "Ralph Finch" Sent: Saturday, March 07, 2009 8:25 AM Subject: AeroElectric-List: ACS's Lightsaver gadget > > > > Aircraft Spruce offers this gadget > (http://www.aircraftspruce.com/catalog/elpages/lightsaver.php) to > eliminate > the large current inrush to a cold tungsten filament, thus supposedly > greatly increasing lamp life. Sounds reasonable, but wonder what the > experts think. And I'm curious why it has to be mounted on a heat-sink > surface...does it consume lots of energy while the lamp is on? > > "WHY INSTALL A LIGHTSAVER > Typical landing and taxi lights in aircraft utilize a lamp that has a > tungsten filament. Tungsten, which is a special metal, produces relatively > high efficiency white light when electrical current flows through it. > Tungsten wire is wound between two electrodes within the lamp. > Unfortunately > the metal wire has an undesirable characteristic. The metal filament has > an > extremely low electrical resistance when the temperature of the tungsten > filament is at ambient (25C). Once the lamp is turned on, the filament > resistance changes from close to 0 ohms (dead short) to 1.5 ohms. An > increase of approximately 100 times. The dead short condition causes a > massive inrush of current for several mille seconds. A typical 100 watt 12 > volt lamp which when on draws 8 to 9 amps may see 800-1000 amps for that > split second depending on the charged condition of the aircrafts battery. > This causes severe stress to the lamp filament, which over repeated on/off > cycles results in a fracture (open) in the filament. This is why the > failure > of the lamp typically occurs at turn on. > > HOW A LIGHTSAVER WORKS > The Lightsaver prevents this massive inrush allowing the filament to draw > the rated current even at turn on with no change in typical light output > performance. The filament life increases up to 10 times due to reducing > the > stress induced by inrush current. This is something the lamp manufacturers > don't want you to know. After all they are in the business of > manufacturing > replacement lamps for your aircraft. > > HOW IS THE LIGHTSAVER INSTALLED INTO MY AIRCRAFT? > The installation is simple. The Lightsaver is placed in series with the > lamp > on either the positive or negative side of the electrical interconnection. > The Lightsaver must be mounted to a heat-conducting surface such as the > firewall of the aircraft. Mounting is accomplished using screws and nuts > to > secure it to the firewall." > > > ________________________________ Message 4 _____________________________________ Time: 09:48:49 AM PST US From: "B Tomm" Subject: RE: AeroElectric-List: ACS's Lightsaver gadget Can I assume these current limiters will also enable the switch that controls the lights to last longer by reducing the arc on switch closure? Or is the arc mostly on switch opening, where the current limiter will have no benefit? Bevan -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Vern Little Sent: Saturday, March 07, 2009 9:03 AM Subject: Re: AeroElectric-List: ACS's Lightsaver gadget --> These devices look like standard power resistors available from Digikey and others. What I use are inrush current limiters (also from Digikey) that have a negative temperature coefficient so that they have a high resistance when cold, but a low resistance when warm. See http://search.digikey.com/scripts/dksearch/dksus.dll?Detail&name=KC023L-ND These are the ones I used for my 75W halogen lamps. The only side-effect may be that a wig-wag flasher may need to be modified to slow down the flashing rate to ensure maximum lamp brightness during operation. I believe that they are better than resistors in this application. Cheers Vern Little ----- Original Message ----- From: "Ralph Finch" Sent: Saturday, March 07, 2009 8:25 AM Subject: AeroElectric-List: ACS's Lightsaver gadget > > > > Aircraft Spruce offers this gadget > (http://www.aircraftspruce.com/catalog/elpages/lightsaver.php) to > eliminate > the large current inrush to a cold tungsten filament, thus supposedly > greatly increasing lamp life. Sounds reasonable, but wonder what the > experts think. And I'm curious why it has to be mounted on a heat-sink > surface...does it consume lots of energy while the lamp is on? > > "WHY INSTALL A LIGHTSAVER > Typical landing and taxi lights in aircraft utilize a lamp that has a > tungsten filament. Tungsten, which is a special metal, produces relatively > high efficiency white light when electrical current flows through it. > Tungsten wire is wound between two electrodes within the lamp. > Unfortunately > the metal wire has an undesirable characteristic. The metal filament has > an > extremely low electrical resistance when the temperature of the tungsten > filament is at ambient (25C). Once the lamp is turned on, the filament > resistance changes from close to 0 ohms (dead short) to 1.5 ohms. An > increase of approximately 100 times. The dead short condition causes a > massive inrush of current for several mille seconds. A typical 100 watt 12 > volt lamp which when on draws 8 to 9 amps may see 800-1000 amps for that > split second depending on the charged condition of the aircrafts battery. > This causes severe stress to the lamp filament, which over repeated on/off > cycles results in a fracture (open) in the filament. This is why the > failure > of the lamp typically occurs at turn on. > > HOW A LIGHTSAVER WORKS > The Lightsaver prevents this massive inrush allowing the filament to draw > the rated current even at turn on with no change in typical light output > performance. The filament life increases up to 10 times due to reducing > the > stress induced by inrush current. This is something the lamp manufacturers > don't want you to know. After all they are in the business of > manufacturing > replacement lamps for your aircraft. > > HOW IS THE LIGHTSAVER INSTALLED INTO MY AIRCRAFT? > The installation is simple. The Lightsaver is placed in series with the > lamp > on either the positive or negative side of the electrical interconnection. > The Lightsaver must be mounted to a heat-conducting surface such as the > firewall of the aircraft. Mounting is accomplished using screws and nuts > to > secure it to the firewall." > > > ________________________________ Message 5 _____________________________________ Time: 11:12:17 AM PST US From: "Richard E. Tasker" Subject: Re: AeroElectric-List: ACS's Lightsaver gadget Mostly the latter. However, that is not to say that they won't benefit the switch by limiting the current surge on turn-on. B Tomm wrote: > > Can I assume these current limiters will also enable the switch that > controls the lights to last longer by reducing the arc on switch closure? > Or is the arc mostly on switch opening, where the current limiter will have > no benefit? > > Bevan > > -----Original Message----- > From: owner-aeroelectric-list-server@matronics.com > [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Vern > Little > Sent: Saturday, March 07, 2009 9:03 AM > To: aeroelectric-list@matronics.com > Subject: Re: AeroElectric-List: ACS's Lightsaver gadget > > --> > > These devices look like standard power resistors available from Digikey and > others. > > What I use are inrush current limiters (also from Digikey) that have a > negative temperature coefficient so that they have a high resistance when > cold, but a low resistance when warm. > > See > http://search.digikey.com/scripts/dksearch/dksus.dll?Detail&name=KC023L-ND > > These are the ones I used for my 75W halogen lamps. > > The only side-effect may be that a wig-wag flasher may need to be modified > to slow down the flashing rate to ensure maximum lamp brightness during > operation. > > I believe that they are better than resistors in this application. > > Cheers > Vern Little > > > ----- Original Message ----- > From: "Ralph Finch" > To: > Sent: Saturday, March 07, 2009 8:25 AM > Subject: AeroElectric-List: ACS's Lightsaver gadget > > > >> >> >> Aircraft Spruce offers this gadget >> (http://www.aircraftspruce.com/catalog/elpages/lightsaver.php) to >> eliminate >> the large current inrush to a cold tungsten filament, thus supposedly >> greatly increasing lamp life. Sounds reasonable, but wonder what the >> experts think. And I'm curious why it has to be mounted on a heat-sink >> surface...does it consume lots of energy while the lamp is on? >> >> "WHY INSTALL A LIGHTSAVER >> Typical landing and taxi lights in aircraft utilize a lamp that has a >> tungsten filament. Tungsten, which is a special metal, produces relatively >> high efficiency white light when electrical current flows through it. >> Tungsten wire is wound between two electrodes within the lamp. >> Unfortunately >> the metal wire has an undesirable characteristic. The metal filament has >> an >> extremely low electrical resistance when the temperature of the tungsten >> filament is at ambient (25C). Once the lamp is turned on, the filament >> resistance changes from close to 0 ohms (dead short) to 1.5 ohms. An >> increase of approximately 100 times. The dead short condition causes a >> massive inrush of current for several mille seconds. A typical 100 watt 12 >> volt lamp which when on draws 8 to 9 amps may see 800-1000 amps for that >> split second depending on the charged condition of the aircrafts battery. >> This causes severe stress to the lamp filament, which over repeated on/off >> cycles results in a fracture (open) in the filament. This is why the >> failure >> of the lamp typically occurs at turn on. >> >> HOW A LIGHTSAVER WORKS >> The Lightsaver prevents this massive inrush allowing the filament to draw >> the rated current even at turn on with no change in typical light output >> performance. The filament life increases up to 10 times due to reducing >> the >> stress induced by inrush current. This is something the lamp manufacturers >> don't want you to know. After all they are in the business of >> manufacturing >> replacement lamps for your aircraft. >> >> HOW IS THE LIGHTSAVER INSTALLED INTO MY AIRCRAFT? >> The installation is simple. The Lightsaver is placed in series with the >> lamp >> on either the positive or negative side of the electrical interconnection. >> The Lightsaver must be mounted to a heat-conducting surface such as the >> firewall of the aircraft. Mounting is accomplished using screws and nuts >> to >> secure it to the firewall." >> >> >> >> >> >> >> > > > -- Please Note: No trees were destroyed in the sending of this message. We do concede, however, that a significant number of electrons may have been temporarily inconvenienced. -- ________________________________ Message 6 _____________________________________ Time: 12:16:03 PM PST US From: "Vern Little" Subject: Re: AeroElectric-List: ACS's Lightsaver gadget If you look at switch ratings, when they are connected to a lamp load, the rating is greatly reduced. This is because of the large inrush currents when filaments are cold. The inrush current limiters will help limit this current, boosting switch life. Vern ----- Original Message ----- From: "B Tomm" Sent: Saturday, March 07, 2009 9:45 AM Subject: RE: AeroElectric-List: ACS's Lightsaver gadget > > > Can I assume these current limiters will also enable the switch that > controls the lights to last longer by reducing the arc on switch closure? > Or is the arc mostly on switch opening, where the current limiter will > have > no benefit? > > Bevan > > -----Original Message----- > From: owner-aeroelectric-list-server@matronics.com > [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Vern > Little > Sent: Saturday, March 07, 2009 9:03 AM > To: aeroelectric-list@matronics.com > Subject: Re: AeroElectric-List: ACS's Lightsaver gadget > > --> > > These devices look like standard power resistors available from Digikey > and > others. > > What I use are inrush current limiters (also from Digikey) that have a > negative temperature coefficient so that they have a high resistance when > cold, but a low resistance when warm. > > See > http://search.digikey.com/scripts/dksearch/dksus.dll?Detail&name=KC023L-ND > > These are the ones I used for my 75W halogen lamps. > > The only side-effect may be that a wig-wag flasher may need to be modified > to slow down the flashing rate to ensure maximum lamp brightness during > operation. > > I believe that they are better than resistors in this application. > > Cheers > Vern Little > > > ----- Original Message ----- > From: "Ralph Finch" > To: > Sent: Saturday, March 07, 2009 8:25 AM > Subject: AeroElectric-List: ACS's Lightsaver gadget > > >> >> >> >> Aircraft Spruce offers this gadget >> (http://www.aircraftspruce.com/catalog/elpages/lightsaver.php) to >> eliminate >> the large current inrush to a cold tungsten filament, thus supposedly >> greatly increasing lamp life. Sounds reasonable, but wonder what the >> experts think. And I'm curious why it has to be mounted on a heat-sink >> surface...does it consume lots of energy while the lamp is on? >> >> "WHY INSTALL A LIGHTSAVER >> Typical landing and taxi lights in aircraft utilize a lamp that has a >> tungsten filament. Tungsten, which is a special metal, produces >> relatively >> high efficiency white light when electrical current flows through it. >> Tungsten wire is wound between two electrodes within the lamp. >> Unfortunately >> the metal wire has an undesirable characteristic. The metal filament has >> an >> extremely low electrical resistance when the temperature of the tungsten >> filament is at ambient (25C). Once the lamp is turned on, the filament >> resistance changes from close to 0 ohms (dead short) to 1.5 ohms. An >> increase of approximately 100 times. The dead short condition causes a >> massive inrush of current for several mille seconds. A typical 100 watt >> 12 >> volt lamp which when on draws 8 to 9 amps may see 800-1000 amps for that >> split second depending on the charged condition of the aircrafts battery. >> This causes severe stress to the lamp filament, which over repeated >> on/off >> cycles results in a fracture (open) in the filament. This is why the >> failure >> of the lamp typically occurs at turn on. >> >> HOW A LIGHTSAVER WORKS >> The Lightsaver prevents this massive inrush allowing the filament to draw >> the rated current even at turn on with no change in typical light output >> performance. The filament life increases up to 10 times due to reducing >> the >> stress induced by inrush current. This is something the lamp >> manufacturers >> don't want you to know. After all they are in the business of >> manufacturing >> replacement lamps for your aircraft. >> >> HOW IS THE LIGHTSAVER INSTALLED INTO MY AIRCRAFT? >> The installation is simple. The Lightsaver is placed in series with the >> lamp >> on either the positive or negative side of the electrical >> interconnection. >> The Lightsaver must be mounted to a heat-conducting surface such as the >> firewall of the aircraft. Mounting is accomplished using screws and nuts >> to >> secure it to the firewall." >> >> >> >> >> >> > > > ________________________________ Message 7 _____________________________________ Time: 02:09:50 PM PST US Subject: AeroElectric-List: one to multiple From: Dan Ballin I am trying to connect an RS232 gps output to many devices (4-5) and wanted an easy foolproof method. I've considered just butt splicing them together ( hard if I want to add another later), butt splicing a few pigtails ( good for later expansion), and I've thought about using a D-sub (more complicated but easier to modify later). Of course I've also thought about soldering vs using butt splice. Just too many ways to skin the cat. Anyone have a better mousetrap? thanks Dan Lancair Legacy ________________________________ Message 8 _____________________________________ Time: 04:05:18 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: ACS's Lightsaver gadget At 10:25 AM 3/7/2009, you wrote: > >Aircraft Spruce offers this gadget >(http://www.aircraftspruce.com/catalog/elpages/lightsaver.php) to eliminate >the large current inrush to a cold tungsten filament, thus supposedly >greatly increasing lamp life. Sounds reasonable, but wonder what the >experts think. And I'm curious why it has to be mounted on a heat-sink >surface...does it consume lots of energy while the lamp is on? >"WHY INSTALL A LIGHTSAVER >Typical landing and taxi lights in aircraft utilize a lamp that has a >tungsten filament. Tungsten, which is a special metal, produces relatively >high efficiency white light when electrical current flows through it. >HOW IS THE LIGHTSAVER INSTALLED INTO MY AIRCRAFT? >The installation is simple. The Lightsaver is placed in series with the lamp >on either the positive or negative side of the electrical interconnection. >The Lightsaver must be mounted to a heat-conducting surface such as the >firewall of the aircraft. Mounting is accomplished using screws and nuts to >secure it to the firewall." This is a stretch of factual data into a pretty good bucket of floobydust. Yes, the cold resistance on an incandescent lamp is quite low compared to it's operating resistance. At the same time, when you close the switch, the lamp doesn't see 14 volts either. There is resistance associated with ship's wiring that adds to the cold resistance of the lamp. Here's a trace I took on a 55W halogen lamp some years ago. http://www.aeroelectric.com/Pictures/Curves/Exemplar_Incandescent_Lamp_Inrush.gif This was with SHORT leads on the workbench . . . and yes, a 100w lamp would be a bit worse. However, I doubt that it exceeds 100 Amps and no where near the 800 amps claimed in the ad. The thing about lamp life is a bit bogus too. Back in the good ol' days when a 4509 tractor lamp was considered a go landing light, they were indeed service life limited by vibration and inrush cycling . . . but even then, how many hours does a landing light burn per year as compared to a tractor . . . or even headlights on your car? Then halogens came to the cars . . . and some years later to airplanes (aviation IS leading edge technology . . . right? Yeah . . . right!). The inrush currents went up slightly but the service life of the filaments went way up. How often do you put new bulbs in your car these days? I think my 2002 van has had one set of headlamps since new. Okay, how about this inrush mitigation if you're using wig-wags? See: http://www.aeroelectric.com/Pictures/Curves/Wig_Wag_Currents.jpg Here's the same lamp as the first trace except flashed at 500 mS intervals. Note that we do see the initial inrush on first-power but the lamp doesn't have enough time to cool off between flashes to repeat the inrush on second and subsequent applications of power. Further, I'm mystified by the picture of the device offered by aircraft spruce. It appears to be the same package as the RH series mil-spec power resistors. See: http://www.alliedelec.com/Search/ProductView.aspx?IMG=895-0400 Of course, someone COULD package some device other than a resistor in that housing but . . . See: http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=656273&keywords=inrush%20limiter Run down the selections for current and hit on 8A. Click on the KC023L-ND and you find a device that can go in series with a 100W lamp that adds 1.3 ohms of resistance to the lamp circuit when cold. Add anther .2 ohms for lamp, perhaps .3 ohms for wiring and we're up to 2.8 ohms. 14V/2.8 = 5A for the new inrush. In operation, the KC023L resistance drops to .04 ohms which means it tosses off about 300 millivolts of your lamp supply power. Here's the ace-kicker. For a KC023L to do it's job, it NEEDS TO BE ALLOWED TO GET HOT. That's what causes its resistance to drop down to a handful of milliohms. The device pictured in the ACS catalog says it needs to be heat-sinked. Hmmmm . . . do you suppose the product pictured is just a resistor? Adding say .1 ohms fixed resistance to the circuit would reduce that many hundreds of amps of claimed inrush to something around 140 . . . assuming one could ignore all the other resistances associated with the wiring. My first pass at this product's claims suggests that first it is not offered with a full understanding and explanation of the simple-ideas that control incandescent lamp inrush but more important, it ignores the relative ruggedness of modern halogen lamps and the non-worry about using them in wig-wag service. If you really, Really, REALLY want to add inrush limiting to your incandescent lamps, I'll suggest you pick one from the Digikey listing cited above for a whole lot less money. If you want my advice, I was in a group of techno-wiennies that looked into using these on the GP-180 at Lear. We did put one in the nose gear taxi light fixture . . . and discovered that you have to mount them so that the DONT get heat-sinked . . . lest they blow up. They need to warm up to work. They're a pain in the arse to mount . . . not unlike polyfuses. If the Lightsaver guys were offering a real, negative tempco inrush limiter, it would be in some sort of package that ALLOWED heating. Bottom line . . . I'll suggest you save your money. Return on investment for these things is poor to nil. Bob . . . ________________________________ Message 9 _____________________________________ Time: 04:20:20 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: ACS's Lightsaver gadget At 02:11 PM 3/7/2009, you wrote: > > >If you look at switch ratings, when they are connected to a lamp >load, the rating is greatly reduced. This is because of the large >inrush currents when filaments are cold. The inrush current >limiters will help limit this current, boosting switch life. > >Vern Great point! . . . I missed this thought in my earlier posting. Consider that when you "close" a switch, the contacts bounce many times. See: http://www.aeroelectric.com/Pictures/Curves/switch_transition_S700-1.jpg This bounce and transition trace on a Carling toggle shows about 1.8 mS to travel from one condition to the other. When I spread that bounce out to count the closures there was about 6-7 as I recall. Relays can be even worse. The heavier their contacts, the worse they bounce. See: http://www.aeroelectric.com/Pictures/Curves/S704-1_Contact_Bounce_without_Diode.jpg http://www.aeroelectric.com/Pictures/Curves/S704-1_Contact_Bounce_with_Diode.jpg These two traces are for the contacts of the plastic 30A relay (S704). These things bounce like Tigger at a birthday party. What's more, all the bouncing happens in that very tiny interval of high inrush for warming up the incandescent lamp filament. This means that an 10A switch controlling an 8A lamp sees perhaps a dozen or more 40A "hits" every time you turn on a cold lamp. That's why lamp ratings on switches are so heavily de-rated. If you want to put an inrush limiter on you landing lights, do it for the switch . . . not the lamp. Thanks for the heads-up Vern. 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.