From: "Jon Finley" Date: Sat, 27 Apr 1996 10:15:07 +0000 Subject: COZY: CHT Senders-CSA April, '96 Can anyone provide more information regarding the homemade CHT sending units mentioned in the April 1996 Central States Newsletter on page 18? It appears the idea is to use a regular thermocouple wire, insert thru a copper tube, soldier the ends together, and insert into a AN bolt(for attaching to engine). Is it really this simple?? Does one have to use a thermocouple lead or is there another substitute that works? Thanks Date: Sat, 27 Apr 1996 16:19:24 -0400 (EDT) From: Randy Crutfield Subject: Re: COZY: CHT Senders-CSA April, '96 Jon, Just went back and read my previous reply and it left a little to be desired. Well, it was close to lunch and I was hungry. :-). The diode method that I described would require that you build your own interface unit that would work with the diodes characteristics. This is probably a little more than you want to do. I am on chapter 7 and have thought about engine monitoring for awhile now and I don't believe that I want to build my own. Even if I did, I would probably go microprocessor based with thermocouples. The advantage to the thermocouple idea is that they are so cheap to make. You simply buy the wire, cut it to length, form the two conductors into a joint on one end and hook the wires up to your monitoring unit on the other end. The principle relies on the characteristics of the two dissimilar metals creating a voltage as the temperature changes. Believe it or not, this also works in reverse, you can apply a voltage and get the thermocouple joint to cool or heat. There are some solid state refrigerators for automobiles that use this principle. One thing that comes into play here, is the joints in the wire. Ideally you only have one joint at the end of the wire where the temperature will be monitored. This joint should only have the welded ball at the end of the wire as I described in the first message. Any twists in the exposed wire causing the two wires to come into contact with each other, have the potential to form another measuring junction. This is possible, but not usually a problem. Any twists between the joint and where the wires are insulated from each other should be avoided. Also, the wires should be a continuous run from the joint to the monitoring unit. If this can't be avoided, there are special terminal strips for use with thermocouple wire. Any junction between the joint and the monitoring unit has the potential to become another sensing point. It is not uncommon in industrial applications for these junctions to be formed in the wire run. If not done properly this junction can add or subtract ambient temperature from the actual temperature being measured. It is for this reason that they should be avoided. As for twisting the wires together and soldering them at the end to form the junction, this is not ideal, but will probably work. Be warned though that the wire you use (chromel-alumel) will not readily accept solder. For destructive testing of a product, I have seen this method used to create a joint that would last for the duration of the test. Acid flux was used to prep the wires for solder. Again this is probably not what you want to do for you engine monitoring. To make the welded joint, you might want to experiment (be careful!!) with a variable transformer like is used to heat the wire for the foam. Naturally you should start off at a low voltage setting and increase it until you start getting an arc. An alligator clip back from the joint can provide the connection on the thermocouple wire which should then be brought into proximity with the other terminal until the arc occurs between the twisted wire and the terminal. Remember, the objective is to have a ball formed at the end of the wire, and no twists after that on the exposed wire. If you make many of these, you will probably want to use some material other than the terminal on the transformer for the terminal, as scavenging of the material will occur each time a joint is made. A good way to check your joints is to hook them up to your display unit and use an ice-water bath for 32 degrees and boiling water for 212. If you are okay at these two points, it should work just fine. If you work somewhere that uses instrumentation, ask the right people if you have a millivolt pot. It is a device that will display the temperature that your joint is producing and also have a feature that will allow you to generate millivolt signals to check your indicating unit. With this they should have the tables for the millivolts generated by the different type thermocouples at various temperatures. I have been away from this for awhile now, but the new digital VOM's should work as well. Most of the better ones should be able to measure in the millivolt range that you are interested in. Some also have inputs for thermocouples and will indicate temperature on their displays. Just make sure that the type thermocouple they use is the same type that you are using. As mentioned earlier, I have never tried to mount them on an engine for sensing, but I would be tempted to try the method of drilling out the bolt and epoxying the thermocouple inside. Of course the appropriate epoxy, RTV, etc, would need to be used for the temperature. The wire is available in a couple of different insulations. I believe for our application a teflon insulation should work fine. The wire itself comes in different types (chromel-alumel, iron-constantine, etc) and cannot be interchanged due to different values of voltage produced per temperature change. I'm going from memory here, and can't remember if you want type J or K wire. Your unit should tell you, and if not, someone else can post and let you know. Hope this helps, Randy Date: Sat, 27 Apr 1996 18:23:24 -0400 (EDT) From: Kenneth Brimmer Subject: COZY: Engine Monitors I highly recomend the Vision Micro System monitor. It is expensive but it sure reduces the pucker factor. I did this kind of work for a while and after reviewing all the different suppliers of this equipment I thought it was the best. After 320 hrs I still think it is. Ken Brimmer brimmer@erols.com "It's easy to build a plane that will last a life time." - Stolen Date: Sat, 4 May 1996 13:07:03 -0400 (EDT) From: Randy Crutfield Subject: Re: COZY: CHT Senders-CSA April, '96 Okay, first day back to work was hectic, and it was late before I remembered the Thermocouple info, but I did remember. The book that I am using for a reference is from Omega Engineering and was copyrighted in 1992. It is titled "The Temperature Handbook". The book covers all aspects of measurement including probes, wire, controllers, and all the technical data that you might need for your application including the conversion tables from degrees to millivolts. I am not sure about their policy today, but they used to send out a small set of encyclopedias on their products for the asking. This book is hardback, and the size of a very large textbook. Their hotline for book orders is 1-800-222-2665. In regards to the specifics that you asked about (connectors, terminal strips, etc.) Here are some examples: A two prong connector for type K (chromel-alumel) that will handle up to 20 gauge wire is listed as $4 to $5 a pair (male and female). Lugs that are made out of chromel or alumel are $10 for twenty. You would have to order a set of each unless Omega would be willing to mix the quantities at 10 and 10 for you. These are not wire lugs, but lugs that fit between the barrier strips on an existing terminal strip to convert it to a thermocouple terminal strip. A bare 20 lug terminal strip is listed for $9 (you would need the lugs mentioned above to complete it). They also list thermocouple wire. For 200 feet of 20 gauge type K wire with glass insulation the price is $125. With Teflon insulation the price goes up to about $200.00. The reason I list 200 feet is that this should be more than enough wire for 8 probes. I list glass insulation because the teflon is only good up to 500 degrees F. The glass is listed as good to 900 degrees F. I am not sure about the error that you would experience using the regular copper plated terminal strip, and don't have the time right now to experiment. I don't believe that the error is significant, but would be reluctant to say without trying it. If you have your RMI unit ready, why don't you experiment with your probes and ice water, boiling water and let me know. You should place your probe at the surface of the containers for the best indication. Hopes this helps, Randy From: Lee Devlin Subject: Re: COZY: Coax cable Date: Mon, 3 Jun 96 13:53:04 MDT Stet wrote: > interference to screw up the readings. All instrumentation wiring is in > shielded twisted pair cable that's grounded at the instrument per Rocky > Mountain instructions. What do you think? Will I have a problem with the > instrumentation wiring in the same conduit as the antenna coax? I have spent a lot of time chasing problems related to a phenomena known as RFI (radio frequency interference) susceptability. Breifly stated, this problem occurs when you are trying to measure extremely small amounts of electrical energy which is getting clobbered by a radio frequency transmitter. Many devices produce radio energy. Anything that produces sparks emits RF energy across the entire radio frequency band. Strobes have large current surges that also produce RF. There are generally two approaches to solving the problem. 1. You can contain or eliminate the source. 2. You can make the measuring device insensitive to the noise. Coax cable works very well as a transmission line because the return path of the signal is in the opposite direction and coincident with the transmitted signal. This cancels out the fields that would normally radiate from an unshielded wire pair. It may or may not provide any relief for unintentional transmission sources (magneto P-leads, strobes, etc.) since they are unintentional RF generators and thus may end up inducing a current in the shield which does not get cancelled by a return current in the center conductor(s) but instead radiates and couples into sensor wires. In this case, it's better to eliminate the source of RF back near the source by installing an RF filter. Another way to eliminate the phenomena would be to filter the leads on the sensors. None of the monitoring devices on an aircraft need to respond to quick (< microsecond) changes in input so a filter that prevents the RF energy from entering the device is a good precaution. In general, I've found that RF energy entering a thermocouple sensing amplifier can be eliminated by adding very small (~470pF) capacitors between each signal wire and ground as near as possible to where the signal enters the amplifier. It is essential that the capacitors to ground are connected to a low impedance ground (e.g. a buss bar or large diameter braided wire connected to an electron sink like the enclosure of the monitor) and not through a length of wire as the inductance in the wire will render the capacitors ineffective. Generally, a thermocouple sensor will produce an 'offset' when it is being interfered with. That is, if you transmit on your comm radio and notice that your cylinder head temperatures decrease 50 degrees in a matter of seconds and then go back to normal when you stop transmitting, then your only solution would be to filter the sensors. Also, a jump in the temperatures when the ignition system is firing is also good evidence that your ignition system is producing unwanted radiated noise. I don't think that you need to worry much about the coax radiating the signal on its shield. However, if you find that the field which you produce intentionally while transmitting is a concern, then you will need to work on filtering the sensor wires. Lee Devlin Date: Mon, 3 Jun 1996 21:00:06 -0700 (PDT) From: Chuck Wolcott Subject: COZY: RE: Wing wiring response Regarding Jim Hocut's comments on grounding the shielding: He is emphasizing the importance of not creating what is called a "ground loop." Which can actually create more problems than no shielding at all. Ground one end only,at the instrument panel to a common bus. I am NOT an Electrical Engineer, but followed all this advice in my Cozy, and it has worked beautifully with NO electrical noise. "MES"...well that's a new one...I like that! I have always heard this stuff referred to as "FM"....(----in' magic) One more thing to mention - I was surprised last weekend just prior to a trip. I wired my master switch solenoid upstream of the starter solenoid just as Nat recommends in the plans, and emphasized in the Newsletter. It seemed logical and a good idea at the time. After almost 2 years of use...the starter solenoid "hung up," and I was able to quickly force an immediate disconnect. Something I thought 'would never happen to me,' since I purchased both solenoids new. From what I understand, a solenoid and the low voltage from infrequently used aviation batteries is the culprit. Just a story to suggest consideration of this idea. Chuck Wolcott Cozy Mark IV / N154CW chuckw@qnet.com Camarillo Airport, CA by InfoAve.Net (PMDF V5.0-6 #4800) id <01I9IRDYUJG08WZGA2@InfoAve.Net>; Sun, 15 Sep 1996 20:33:36 -0400 (EDT) Date: Sun, 15 Sep 1996 20:33:36 -0400 (EDT) Date-Warning: Date header was inserted by InfoAve.Net From: Nick Ugolini Subject: COZY: Micro Encoder Group, I just finished my altitude encoder/computer/does about everything kit. It is by Rocky Mountain Instrument. I VERY highly recommend it. Anything that you can think of to compute from the static and pitot and temp info. this micro computer does it!! Such as VSI, altitude, presure altitude, density altitude, OAT, true air speed, alarms out the ying yang (Vne, Vno, stall, gear not down, flaps and a bunch more) you get the drift. It took about 15 hrs to build and worked perfectly the first time I powered it up. Sure surprised me!! It is going to take me a week just to figure out how to use all the features. Assembly way very easy. The instruction book were absolutely the best I have every seen (I have built a few other kits). Parts were neatly layed out and identified on cards and in packets. Even the IC's were put in their anti-static holder in the order you have to install them. A tremendous amount of thought and attention to the smallest detail went into this outstanding kit. Anyway, I just wanted to tell the group this encoder is a definite BUY. Besides, it really looks snarky sitting on my desk. Nick Ugolini unick@mail.charleston.net Varieze N89RS From: Ken Reiter Date: Mon, 16 Sep 96 10:32:54 CDT Subject: Re: COZY: Micro Encoder Group, I just had to second Nick's words on the Rocky Mountain Products. I do not have the uEncoder but do have the uMonitor (Engine Monitor) and like Nick said this one also does just about everything you would want checked or displayed oe monitored. Likewise, I also bought the kit and built it over the xmas holiday. Manuals are VERY well done and I can not think of anything to change - the viewing angle is very wide - I radio stack just left of center with the uMonitor to the left of the stack - no problem with viewing. At present, I am wiring the CozyIII and plan to fly before the end of the year. Ken Reiter Plano, TX Date: Fri, 01 Nov 1996 17:54:13 -0500 From: Paul Burkhardt Subject: COZY: DG gyros Does anyone know where I can find a 14v Directional Gyro(backlit). They seem impossible to find. The list price is around 1500.00. Considering I could probably install a complete vacuum system for the price of a single new gyro, I can't jusify the new price. I do have a newly rebuilt horizon gyro I purcased 14v (newly painted face-backlit w/wiring harness)That I will sell if I cant find a decent price on a used DG unit. Its made by RC allen w/cage Knob. I will sell it for 900.00 if I cant find a DG soon. I'm cutting my panel out and need to know where I'm going with it soon. PS. I Wish I had put 5 plys on the front of the panel rather than what the plans call for. It would be much easier to install not only the instruments, but also the switches Which just don't seem to come with 1/2 in bushings. Nuts nuts nuts Paul Burkhardt by mta bnr.ca in /PRMD=BNR/ADMD=TELECOM.CANADA/C=CA/; Relayed; Fri, 1 Nov 1996 18:41:30 -0500 by /PRMD=BNR/ADMD=TELECOM.CANADA/C=CA/; Relayed; Fri, 1 Nov 1996 18:40:48 -0500 by /PRMD=BNR/ADMD=TELECOM.CANADA/C=CA/; Relayed; Fri, 1 Nov 1996 18:38:00 -0500 Date: Fri, 1 Nov 1996 18:38:00 -0500 [/PRMD=BNR/ADMD=TELECOM.CANADA/C=CA/;bcars735.b.618:01.10.96.23.40.48] From: "michael (m.j.) anderson" Subject: re:COZY: DG gyros In addition to Paul's comment about the instrument panel, the following is an excerpt of a posting that I posted while back. > I recently completed chapters 4 and 5 and had Vance Atkinson > look at them. As he was looking at my instrument panel, he asked me > how I was planning to install the instruments. I said "Gee, I don't > know". He gave me the following tips: > > - Add about an additional 5 layers of glass to the upper aft side ( > the part where you would see the instruments). And when you install > the instruments from behind you remove the foam up to the back of > the glass and install the instrument. This way you won't have the > tunnel affect and the instruments would be flush. > > - Vance had also indicated that I may want to do away with the upper > stiffener, for it may get in the way when installing the > instruments, circuits breakers, etc. But keep the other ones for > the are great for routing the wire bundles. > > Vance had also indicated that a lot of people install the metal panels > which screw into tabs on the inside of the fuselage. This would > replace the upper portion of the existing instrument panel. Anyways, take it for what it is worth. Michael Anderson mikej@nortel.com Cozy Mark IV #484 Date: Wed, 6 Nov 1996 08:36:26 -0500 From: CheckPilot@aol.com Subject: Re: COZY: DG gyros In a message dated 96-11-01 18:03:28 EST, you write: << I do have a newly rebuilt horizon gyro I purcased 14v >> Paul, Are you planning on doing any IFR flying?? If you are (or will want to later) I would suggest you put in vacuum gyros. The splitting of the two systems (elec. T?C and vacuum AI/HI) gives you a redundancy that an all electric panel does not, unless you are going to install dual alternators (just saying that I can hear the weight gain). Just my two cents as someone who has had electrical problems in actual IFR (one alternator of a twin). Jim Hann ATP/MEL Cozy III #455 by InfoAve.Net (PMDF V5.0-8 #17060) id <01IDKUKVJD5U906Q1U@InfoAve.Net>; Sun, 29 Dec 1996 10:20:19 -0500 (EST) Date: Sun, 29 Dec 1996 10:20:19 -0500 (EST) Date-Warning: Date header was inserted by InfoAve.Net From: Nick Ugolini Subject: COZY: RMI Micro Monitor I have sent a few messages to Ron Mowrer (RMI) and I thought the Cozy group might be interested in the responses: Start of string ---------------------------------------------------------------------------- ------------------------------------ The messages we were sending reguarding the quality of the Micro encoder kit. -- I copied a few of them to Ron: ----------- From Nick More GOOD comments on your kit from the Cozy group. Of course I had to tell of my success with your kit and the exceptional quality. This message brought out a really good idea. A small circuit that would cycle through the sensors (maybe with an LED to indicate which sensor is on line. Is it possible to use a few micro chips and solid state relays to do the job? Is it something you could market? Or design (and send out a circuit diagram). It certainly would be more eligant than a rotary switch. ------------RON Nick, Thanks for the support and feedback. I just spoke to a new customer yesterday that is an EE and is going to design a scanner to work with the monitor. He was interested in allowing us to use the design and market the kits. He is in the process of building and RV6A so I don't have any idea of the timeframe. Any new stuff will be posted on the website. Regards, Ron Mowrer /^\ /\/ \ Rocky Mountain Instrument / RMI \ http://rkymtn.com ---------------Nick > >I just spoke to a new customer yesterday that is an EE and is going to >design a scanner to work with the monitor. He was interested in allowing >us to use the design and market the kits. > That is GREAT. I think a scanning circuit would be just what is needed for your kit. A couple of thoughts I had on it: At a minimum it should have four (or six) circuits which will have two relays on each circuit. This will allow you to monitor both the CHT and the EGT on each cylinder at the same time. Each circuit should have an LED to indicate which cylinder is being monitored. When alarmed the scanning will stop, the LED lit will be the cylinder with the alarm condition. Each circuit should have a momentary contact switch (next to the LED) will allow you to select the circuit to be manually monitored (without scanning). One momentary switch will re-start the scanning when desired. When you put together the kit, let me know and I will order one and the Micromonitor's............... Thanks -------------End Looks like a channel scanner is being developed. I think I will wait until the the scanner is designed, then I wouldn't hesitate at buying the micro monitor. The kits are fantastic, and I will save a lot of pannel space. Good flying. Nick Ugolini unick@mail.charleston.net Varieze N89RS Cozy Mark IV #0264