---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sat 03/19/05: 10 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:50 AM - Re: headset level to mic level for recording (Ron Brown) 2. 05:28 AM - Re: Crowbar OV Protection (Mike Lehman) 3. 07:44 AM - 2 mutch (Fergus Kyle) 4. 08:23 AM - Re: Points for discussion OVP//more (Paul Messinger) 5. 09:30 AM - GPS Annunciator () 6. 11:59 AM - Re: headset level to mic level for recording (David Carter) 7. 05:21 PM - (Dan O'Brien) 8. 06:48 PM - Re: Points for discussion OVP//more (Dan O'Brien) 9. 07:09 PM - Re: gps annunciator 300xl (CardinalNSB@aol.com) 10. 09:29 PM - Re: Points for discussion OVP//more (John Swartout) ________________________________ Message 1 _____________________________________ Time: 04:50:59 AM PST US From: "Ron Brown" Subject: RE: AeroElectric-List: headset level to mic level for recording --> AeroElectric-List message posted by: "Ron Brown" >I'm not even sure if it's called a "pad" but I think it is... Here's the >deal. I bought a digital voice recorder thing from Radio Smack with the >intention of recording intercom & radio activity in the plane. The recorder >has an 1/8" mic jack, and it has two "sensitivity" settings, hi and lo. I >connected the passenger headset jack to the mic jack on the recorder, and >not surprisingly the recorder is slightly overloaded level-wise. I have the same set up and use an in-line volume control like this one also at the shack. Works great!!! http://www.radioshack.com/product.asp?catalog%5FnameCTLG&product%5Fid42-2559 ________________________________ Message 2 _____________________________________ Time: 05:28:07 AM PST US From: "Mike Lehman" Subject: AeroElectric-List: Re: Crowbar OV Protection --> AeroElectric-List message posted by: "Mike Lehman" My question refers to the VR-166 Ford type voltage regulator with an alternator B+ to regulator terminal 'A' connection supplying alternator field current. When the crowbar protection reduces VR terminal 'S' to under 2 volts, is the field current supply via terminal 'A' always interrupted? I presume that the answer depends on the failure mode of the VR-166 that caused the crowbar to 'fire' in the first place. In other words, with the old mechanical VR-166, I have confidence that the crowbar protection is adequate. Substituting an electronic VR-166 (with the B+ to terminal 'A' wire, not with terminal 'A' and 'S' jumpered per Bob's diagrams) seems to create the equivalent of an alternator with an internal voltage regulator. Hopefully, alternator field current via VR termimal 'A', with terminal 'S' de-energized, is a low probability VR-166 failure mode? Anyone really know ??? Mike ________________________________ Message 3 _____________________________________ Time: 07:44:17 AM PST US From: "Fergus Kyle" Subject: AeroElectric-List: 2 mutch --> AeroElectric-List message posted by: "Fergus Kyle" "Nice attempt at humor but you "digress" to much." Methinks thou dost complain two much. Ferg ________________________________ Message 4 _____________________________________ Time: 08:23:58 AM PST US From: "Paul Messinger" Subject: Re: AeroElectric-List: Points for discussion OVP//more --> AeroElectric-List message posted by: "Paul Messinger" ----- Original Message ----- From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Points for discussion OVP//more > --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" > > > At 08:31 AM 3/15/2005 -0500, you wrote: > >>--> AeroElectric-List message posted by: Matt Jurotich >> . . . but assuming your system > IS capable of producing a 250A trip current, is there > any analysis to support the notion that this is "bad" > for other systems in the aircraft? > > Bob . . . Seems to me you have it backwards (you need to prove its compatible with today's electronics). With today's avionics that may contain sensitive magnetometers as well as truly electric dependent engines where dropping below 11V at the battery can cause the engine computer to reset. Remember all the discussion regarding electronic mags and the need for a special battery during starting to keep the voltage high with the high starting current typical with Lyc's etc?? Then there is the increasing use of Hall effect devices for current sensing. One manufacturer of such devices states that a 100% over current will cause a calibration shift. So much for accurate current measurements. The list of potential concerns seems endless to me. Given that I am working on a 21st century aircraft engine that is derived from an auto engine; I have measured the starting current, including peak currents. The current path does not go close to the instrument panel as the crowbar CB that is mounted there does. A modern geared starter need not have high currents like the stock Lyc starters do. Also with a smaller displacement engine that is geared down, the power to turn it over is much smaller. My need for measuring worst case starting current is an important design requirement when designing solid state contactors. (The design is for 300 amps max starting while cranking and an inrush peak of more than 500 amps). The peak starting current (with the engine I am working with) is under 200 amps (at least as measured with a 500 amp current shunt and a 400 MHz scope system). After a peak of under 200 amps the starting current varies from 110 to 130 amps depending on compression stroke vs. power stroke in the engine. The battery terminal voltage never drops under 11V (but the batteries are not as you suggest but batteries designed for starting etc. ( See a 'to be posted' discussion) The use of old technology (Crowbars) with modern equipment can be a problem and considering that the only supporter of a crowbar (anywhere in general aviation aircraft?) seems to be from you so that puts the burden of proof (that its still a good idea and safe to use) on you. A developer of a new avionics system who only looks at certificated aircraft will not notice your design, nor will those who also inquire with major experimental aircraft manufacturers like Vans. I agree that protection is needed but the old approach of using a crowbar in this way never was the best way and today is no longer a potentially safe approach. A realistic wiring setup (as used in a real aircraft) with a really good battery plus a nominal CB (see CB data sheet) can produce far higher trip currents and much longer trip times that your sample of one test shows). More than enough to cause a reset of the engine computer depending on the variables an individual aircraft might have. Even 250 amps is several times the MIG or TIG welding current needed for a steel tube structure in an aircraft. Surely you would not suggest that the avionics be installed when doing welding in the cockpit area, but in effect, that is what the crowbar does. What bothers me is your the comments about how simple and low parts count it has and has been working for 30 years. Neither has anything to do with our concerns that my testing (and investigations) have demonstrated to me are valid. Also adding just one part to your crowbar could reduce the current surge to a reasonable level and still provide the function of opening the CB. Add another part or two and you can open the "B" lead contactor power (and open the contactor) without resorting to the high current presently used to pop the CB. So 3-4 parts added and no need to pop the CB and no hi current surge. In my opinion this should have been part of the original design. The approach Eric sells has been extensivitely tested by both of us and not only has no current surge but has 100% of the time protection against OV conditions (which your approach does not do; see another upcoming post on this). Also it eliminates the heavy "B" lead contactor (In one of Eric's approaches ). The only down side I see to any of the above is its a change from your traditional approach. It may be of interest that Denso has a belt connected (not gear connected) starter and alternator "all in one" for the modern auto where the engine is stopped every time the auto is stopped. The web pictured device appears to be a simple alternator but actually contains a starter also. Designed 4 years ago! Paul ________________________________ Message 5 _____________________________________ Time: 09:30:33 AM PST US From: Subject: AeroElectric-List: GPS Annunciator --> AeroElectric-List message posted by: AeroElectric-List message previously posted by: "Vern W." <> AeroElectric-List message previously posted by: "Vern W." <> 3/19/2005 Hello Vern, You are struggling with a problem that many of us have confronted so it is worth exploring more in depth. Some comments to assist in this exploration: 1) This is not simply an annunciator problem. When you feed the GRT EFIS (or any CDI) from either the 300XL or the SL-30 you need an interface device (many relays) to transfer all of the appropriate information signal inputs from the sending devices to the receiving device (navigation indicator). 2) And you need a switch or button of some kind to activate that interface device to tell it which source to use to drive the navigation indicator (receiving device). 3) So the fundamental questions are: What are you using as an interface device (a box with many relays inside) and how are you controlling that interface device? 4) Once the interface device is chosen then you have at least three ways to tell which source is feeding the navigation indicator: 4A) A simple two position switch - one position is labeled SL-30 and the other is labeled 300XL. Depending upon which position the switch is in then the interface box relays are connected to feed that source to the navigation indicator. 4B) A push button, split illuminated switch with one half labeled SL-30 and one half labeled 300XL that cycles the interface box between the two sources. Which ever light is lit tells you which source is feeding the interface box. 4C) A plain push botton switch that cycles the interface box between the two sources and two lights on the panel, one labled SL-30 the other labled 300XL, that are fed from relays within the interface box. The appropriate light is lit depending upon which relays are in contact. 5) Some sources for interface boxes with many relays are Perihelion Design (thanks Eric) and Northern Airborne Technologies. 6) This subject of feeding one navigation indicator from two sources has been discussed previously on the list if you want to go back into the archives. Please come back with some additional questions and thoughts on how you want to do this. OC PS: The term "satisfy IFR requirements" raises the questions: Whose IFR requirements are you referring to and where are they documented? Let's not get wrapped around the axle of FAA / FAR requirements for installations in standard type certificated airplanes. ________________________________ Message 6 _____________________________________ Time: 11:59:09 AM PST US From: "David Carter" Subject: Re: AeroElectric-List: headset level to mic level for recording --> AeroElectric-List message posted by: "David Carter" The simplest, non-cut and solder approach is to buy 3 parts from Radio Shack: 1) Radio Shack Y adapter: Male 1/4" plug end goes into your aircraft's larger headset jack. Y adapter has 2 1/4" holes/jacks in top, one for your headset's 1//4" jack and the other for 2) your new Radio Shack 1/8 to 1/4" adapter - plug big end into 2nd hole of Y adapter; 3) Radio Shack 42-2152, 6.5' Attenuating Dubbing Cord, $3.99, which has tiny 1/8" male/jack on each end - plug one into your video recorder's "audio in" (or your digital recorder) and the other into the1/8 to 1/4 adapter [ 2) above ] It cuts the amplitude of the aircraft audo system so my video recorder audio isn't over-driven. It works for me in the Cessna I fly wih a video recorder. David Carter ----- Original Message ----- From: "Ron Brown" Subject: RE: AeroElectric-List: headset level to mic level for recording > --> AeroElectric-List message posted by: "Ron Brown" > > > >I'm not even sure if it's called a "pad" but I think it is... Here's the > >deal. I bought a digital voice recorder thing from Radio Smack with the > >intention of recording intercom & radio activity in the plane. The recorder > >has an 1/8" mic jack, and it has two "sensitivity" settings, hi and lo. I > >connected the passenger headset jack to the mic jack on the recorder, and > >not surprisingly the recorder is slightly overloaded level-wise. > > > I have the same set up and use an in-line volume control like this one also at the shack. Works great!!! > > http://www.radioshack.com/product.asp?catalog%5FnameCTLG&product%5Fid42-2559 > ________________________________ Message 7 _____________________________________ Time: 05:21:04 PM PST US From: "Dan O'Brien" Subject: AeroElectric-List: 1.16 MISSING_SUBJECT Missing Subject: header --> AeroElectric-List message posted by: "Dan O'Brien" >Paul wrote: >A developer of a new avionics system who only looks at certificated > aircraft will not notice your design, nor will those who also inquire >with major experimental aircraft manufacturers like Vans. Hmm... the top composite experimental (Lancair) says in its IVP manual, its ES manual, and its recently updated Legacy manual (see http://www.lancair-kits.com/manual_revisions/Legacy_manual_rev-0105.pdf, p. 27-4): "Robert Nuckolls is also an excellent reference for wiring. He publishes a newsletter, The AeroElectric Connection, and also contracts his services to individual builders to design custom electrical schematics. He can be reached at: Medicine River Press 6936 Bainbridge Road Wichita, Kansas 67226-1008 (316) 685-8617" While specifics of this may be slightly off or dated (is there a "newsletter" we don't know about beyond the website?), this is clearly an endorsement from a pretty big player in the experimental category. Yeah, Lancair is "small" compared to Vans, but I think it's number one among the more "modern" composite players. FWIW. ________________________________ Message 8 _____________________________________ Time: 06:48:26 PM PST US From: "Dan O'Brien" Subject: AeroElectric-List: Re: Points for discussion OVP//more --> AeroElectric-List message posted by: "Dan O'Brien" >Paul wrote: >A developer of a new avionics system who only looks at certificated > aircraft will not notice your design, nor will those who also inquire >with major experimental aircraft manufacturers like Vans. Hmm... the top composite experimental (Lancair) says in its IVP manual, its ES manual, and its recently updated Legacy manual (see http://www.lancair-kits.com/manual_revisions/Legacy_manual_rev-0105.pdf, p. 27-4): "Robert Nuckolls is also an excellent reference for wiring. He publishes a newsletter, The AeroElectric Connection, and also contracts his services to individual builders to design custom electrical schematics. He can be reached at: Medicine River Press 6936 Bainbridge Road Wichita, Kansas 67226-1008 (316) 685-8617" While specifics of this may be slightly off or dated (is there a "newsletter" we don't know about beyond the website?), this is clearly an endorsement from a pretty big player in the experimental category. Yeah, Lancair is "small" compared to Vans, but I think it's number one among the more "modern" composite players. FWIW. ________________________________ Message 9 _____________________________________ Time: 07:09:18 PM PST US From: CardinalNSB@aol.com Subject: AeroElectric-List: Re: gps annunciator 300xl --> AeroElectric-List message posted by: CardinalNSB@aol.com Vern: Before I started a new business and had a head-on accident last year I was thinking I was going to make my own annunciator panel for my Garmin 300xl. Still thinking... Good used 300xl can be had at very reasonable prices, I wasn't about to pay half again just for some lights. I had a good deal of discussions on other boards, here is what I think I know about installing it in my Cesnna Cardinal, a certified aircraft. I emphasize that this is based only on my reading and discussions, that I haven't found any "professionals" that agree with me on my interpretation of the law as being a minor alteration. I appreciate any corrections or affirmations or filling in any gaps: 1. IFR installation of gps is a "minor" mod, only log book entry required unless it is interfaced with something "unusual", based on the AC 20-138, page 11. However, the annunciators and cdi are required in order to be in compliance with Garmin's initial STC. 2. The cost of the "store bought" annunciator panels exceeds a good used King ki202 or collins, I decided to directly drive the cdi and not use a relay. I understand some ARC units will work. You need a resolver in the cdi. 3. The Garmin installation manual shows the needed 6 annunciator lights and 2 switches. Lights 1, 2, 3, and 4 are driven by the output from the gps, through the bulb, then to ground. The gps controls whether the light 1, 2, 3 or 4 is energized. Message and Arrival lights are independent of all other annunciators. Approach Resolution Hi or Low is alternatively selected by a momentary switch to ground a pin, but the switch is not tied to the lights. Lights 5 and 6 Now here is what I find to be odd. The .gps is in "sequence" mode unless the sequence pin is grounded. Not a momentary "flip flop" like the Approach Resolution Mode, rather if its grounded its in Hold Mode and if its not grounded its in Sequence Mode. BUT there is no driver from the gps for the lights in either mode. Instead, the installation drawing shows a dpdt switch-in the up position, the first pole connects power (from the bus, not the gps) to the Sequence light then to ground and the second pole is unconnected. In the down position, power flows to the Hold light through the first pole then to ground and the second pole simply grounds the sequence hold pin, putting the gps in the Hold mode. Seems odd to me that they didn't simply output 6 annunciator lights directly from the gps and control the 2 mode styles with appropriate switching. 4. If you use a relay to switch the cdi between gps/nav, you need another light to indicate the source driving the cdi. I haven't researched much but NAT advertises a relay for this. I see this on ebay often. 5. I didn't see anywhere where it listed the output voltage from the gps for the annunciators, or that the annunciator output level varied with the unit's own dimming function, so I assume the output is a constant 12v when activated. HELP PLEASE. Assuming I got the basic annunciator scheme right, how can I easily make a multiple LED dimmer? So far, I have the face plate off of an old annunciator which I intend to put leds behind so I can use the same white led for each function, so the output of each annunciator will be the same with no need to vary the voltage between the bulbs (I sure do love those blue leds though). The problem I see is that out of the 6 lights, 2 will always be on, sometimes 3, sometimes 4, so if I simply put a rheostat before the (common bulb leg)ground and it is dimmed for 2 lights, and then 4 become activated, there might not be enough voltage to light the leds. Bad if a RAIM message is missed. Would a circuit based on a LM 3914 be appropriate (between the gps and the led), or can someone point me to a source for dimming multiple leds from a common knob. Its a good thing this is a hobby... thank you Skip Simpson but a Light 1 is Message, driven by the Garmin 300xl, grounding the light . Light 2 is activated by an internal relay to ground. Light 3 is activated by an internal relay to ground. Light 4 is activated by an internal relay to ground. Light 5 and 6 are controlled by a dpdt switch. Voltage goes into the dpst switch. In the up position, Light In position up, light is on . 4 lights are activated by . ________________________________ Message 10 ____________________________________ Time: 09:29:37 PM PST US From: "John Swartout" Subject: RE: AeroElectric-List: Points for discussion OVP//more --> AeroElectric-List message posted by: "John Swartout" -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Paul Messinger Subject: Re: AeroElectric-List: Points for discussion OVP//more >There is more to life than this list :-) Really? What's her name? ;] Do Not Archive