The Stratomaster Ultra .

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This is the total sum of my instruments , it has 2 screens switch able one with all flight instruments and the other with up to 12 inputs from the engine or what ever I want to monitor. This is not fixed however it is software configurable so one can display anything and everything on either screen. You can display the output in digital format or analogue format or both if you have enough screen space. I have not got the sensors yet so the only things I can display is altitude and voltage. Both are spot on by the way. It's not displaying my correct altitude in the photo as I had not set the current QNH before I took the photo.

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The sensors have finally arrived. 1st January 2008.

The Tachometer is working, I am feeding a 15v RMS half wave signal in at 50 HZ (Small transformer next to it.) with the setting I have in the Ultra the RPM should be 2000 assuming the supply is exactly 50 Hz which it may not be. It also works with an AC signal but I was experimenting with what works and what does not. When I install it I will use the alternator AC. The fuel gauges are working the outside temp and the Compass are also working. Next is the Oil temp , Oil pressure , Fuel pressure ,Fuel flow and Cylinder head temps , I have 2 CHT sensors but I think I will get another 4. I have 2 EGT sensors as well but that will be fine. When I finish building the Pitot tubes I will try the air speed indicator out in the car by hanging it out the window.(While Margaret is driving of course.)

The Pitot and static sensing tubes 30th April 2008 also my exhaust gas sensors.

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My pressure sensing tubes finished. Static port on the left for altitude and the Pitot on the right for airspeed. The bends came out perfect , I used my home made bender with the tubes packed with fine sand and heated with a gas torch they bent very easily with no distortion at all , I was very happy with them. I am also happy to report I tested them in the car and the speed and altitude compared closely with my GPS.Also the VSI works a treat going up and down hills.

Mounting sockets for the EGT sensors , these weld into the exhaust pipes 4" from the cylinder head with the sensor tip in the centre of the pipe. The sensors screw into them to make a gas tight seal. I am not a big fan of the hose clamp method , apart from looking very bodgie it would not be a very durable gas tight seal.

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More drama , I had to make two new vertical brackets as the bottom bolt was too close to the rivet hole and stopping me from putting it in. While I was at it I made 8 , 1/8" spacers out of some scrap aluminium and got back 16 of my 3/16" washers which were running a bit short. I also took out the screw I had in the static tube and replaced it with a machined down 3/16" rivet as per the plans.

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The last thing was to round off the brackets so they will fit into a 1 7/8" hole. I cut a hole in some scrap for two reasons , first to try out my hole cutter and second to check fit my Pitot setup. Hole cutter worked well and setup fitted in nicely. Finished product centre. Photo on right my panel cut ready for painting.

The Sonex Instrument Panel 14th June 2008.

My instrument panel taking shape.

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Some instruments in, the ball is temporary till I get the giro for the Stratomaster then the ball will be replaced by a Microair transponder. The large holes on the far right are for aux power sockets.

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All in except one green LED on the left and 1 switch on the right. Panel painted, you can't tell in the photo but it came out a lovely flat black I an very happy with it , now I just have to figure out how I am going to get the white printing on AND whether I remain happy.

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Panel nearly there. On the bottom left my aux PTT , the main PTT will be on the control stick but if that ever fails for any reason I can use the one on the panel. With the lead constantly being flexed I am sure this will happen one day. Next the start button (The start button has an electrical lockout system ,once the engine is running the button is disabled), Mag switches , nothing special about these switches except they connect to the ignition systems via shielded coaxial line, grounded at the centre where the cable passes through the fire wall. The reason for the coax is the terminal used for grounding the ignition is connected to the primary coil which produces a several hundred volt spike every time it fires, the last thing you need right next to an AM radio receiver. You must also be conscious of the insulation quality of the leads and any plugs and switches here, I am using RG-58 coax rated 1000v ,good quality switches and BNC connectors. Fuel pump switch. This works with the fuel valve switch. If the valve switch is in the Normal position and the pump is on then the valve will be off so the engine is being supplied from the aux tanks. With the pump switch off then the valve will be on allowing the fuel to flow from the main tank. With the valve switch in the transfer position and the pump on ,the excess fuel from the rear tanks will flow into the main tank. With both switches off then no fuel flows if I want to drain the carby before shutdown. IF I loose power the valve has a manual bypass port.

Above the switches I have some warning lights. You may ask why have warning lights when I have gauges in my Stratomaster. The reason is I like instant gratification , when the engine starts I want to see these 3 red lights go out and when I turn on my power switches I want to see the green LED's come on. The right hand LED (Not installed yet) is connected across the coil of my fuel valve to let me know there is power on the coil.

Above that is my circuit breakers and above them is the warning light for the Stratomaster, this will flash if any of my preset limits are exceeded. The Stratomaster also injects a warning tone into the headsets.

On the right hand side bottom I have carb heat control, Air cleaner control. I can have my Air cleaner in circuit or out. If I am on the ground I would have the air cleaner in circuit but if I am cruising I don't need it so I would bypass it. The best part is if I want carb heat on the ground on a frosty morning I can have my air cleaner as well. Next the oil cooler control, same deal when the oil is cold I will block the air from the cooler, I might make this temperature controlled later on once I get the feel of it. Then the choke , cabin heat and a couple of aux power sockets.

Above on the left I have my intercom switch. Three positions , up intercom on all the time ,hot mike. Centre position off and down is PTT mode. I have used vox systems for years and have never liked them so I am mounting PTT switches on the headset leads about chest level so if the passenger wants to speak they have to push their PTT switch. Apart from better operation it has 2 other advantages. 1. It cuts down on unnecessary cabin chatter and 2. If your passenger is about to speak you get a warning when you see his or her hand move towards the PTT switch.

Then the alternator switch which allows me to turn off my alternator if the regulator fails for example, it is also helpful if you are trying to track down electrical noise to be able to turn off the alternator.

Next is the Amateur radio transmit switch. In the transmit position and with the radio on, both mic's will go out on the Amateur band selected if the intercom PTT switches are operated. Which is the reason for the flashing red on air LED above the switch. Then the Microair light switch. The Av isolate switch , this allows me to disconnect the AV bus from the main bus with the Av bus being supplied by a backup battery.

The test switch is for testing the over voltage circuit. If this circuit detects an over voltage it will disconnect the alternator. The Reset switch resets this circuit. A spare switch and finally a PTT switch, if the passenger needs to operate the air band radio.

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A few people have asked me how I did the printing. Here is the test piece I took to the engravers to try out. I was happy with what he did so I went ahead. The test piece came from the cut-out where the Stratomater goes. The 2 1/4" hole was another test for my fly cutter to see how the holes were going to come out for the radio and ball. The paint was flat black from a spray can.

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My control stick switch installation. I machined up a an insert to push into the end of the tube out of some scrap 3/16" al. The wires will exit the tube at the bottom through a small grommet. I am using some 4 core telephone cable for flexibility and I will double up the wires for an extra bit of redundancy. I searched high and low for a nice little flat switch that would be easy on the thumb. I don't know why I press down with 5 times more force than necessary, one day I will break the habit. (Or the switch)

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The rear box and mounting bracket under construction, I installed all jacks to check fit before painting. Rear view before wiring. The relays are for switching the microphones so that only one works at a time which should cut down on the transmitted noise. The only thing missing is a small audio transformer which will allow me to feed the Amateur Radio external speaker audio into the right hand side earphone. (My headsets can be stereo or mono , switchable.)This allows me to listen to the air band and the amateur band at the same time. In mono I hear only the air band. I love this flat black paint. The finished product. The cables will enter from the rear and connect via a DB15 plug and socket.

The front box under construction. This will mount under the glare shield just behind the panel. Three power relays two audio switching relays and some electronics including the over voltage sense circuit. The printed circuit board I etched myself. The 2 boxes allow me to connect almost everything with 4 multi cored cables with multi pin plugs. I will later make replicas of everything so in the event of a problem I can change any of the modules or cables and repair them on the bench. The instrument panel will be easily removable in case I get a problem with it.

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Front box completed. The large connector connects to the panel the small one connects to a cable to the rear box and the white power connector goes to the firewall.The only other cable goes from the panel to the firewall. My setup for soldering the wires into the connectors. The completed internal wiring , I used automotive style relays for the power which made things a bit tight, the next one I build will have PCB mount relays and that will tidy things up a lot. The aluminium plates are for holding the relays in position and make a good place to ID the relays. If you look closely you can see the diodes connected across the coils to quench the reverse spike that is produced when the relay is released.

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Panel finally in and working (Battery back up only at this stage). Rear box and speaker in , filter capacitor in , I must get some rubber boots for those terminals.

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The coax lines coming through the firewall using BNC connectors. The lines on the engine side and connections to the magneto.

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The Compass. Mounted in the tail as far away from magnetic fields as I could get. I powered it up inside my steel shed and it read 162 degrees. I got out my hand held GPS and walked away from the Sonex in the direction it was pointing and it read 162 degrees, I was impressed.

The cockpit nearly there , The glare shield cover on with some help from Margaret. The windscreen back on for the last time. I just need to put the tail feathers back on and connect up the rudder pedals add a bit of carpet around the foot wells and put the floor on.

The 5th of November 2008 The capacitive fuel probe.

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My fuel level probe for the main tank and the interface. Another challenge I faced as the output of the probe was incompatible with the Stratomaster input. The Stratomaster wants to see a varying resistance as if it were connected to a float / variable resistor setup. Where as the probe electronics output is a varying voltage 0v to 5v probably designed to drive a small meter. I built a small single transistor interface to overcome this which works fine. I have since discovered that the probe manufacturer produces a version WITH a resistive output to suit the Stratomaster. This version has a green signal wire where as mine has a yellow wire. I was tempted to return it and get the correct one but my interface works OK so I am going to go with it. The interface sits inside the box and takes it's power from the same source as the probe, I guess I should make my signal wire green.

Battery box finished , fuel pressure sender in , solenoid in and RDAC mounted , now I need a few more sensors and connect everything up.

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Fuel probe repair

I had the dreaded Sonex fuel smell in the cockpit caused by a drip from the probe. I bought an opps fitting assuming the problem was in the tank but not so , I had a leak in the probe so I dismantled it and put a new fitting on with some JB weld for good measure and "VOILA" no more Sonex fuel smell.

Finished calibrating the Stratomaster by adding fuel 11 litres at a time instead of 15 litres as with the probe. The probe has 5 settings where the Strato has 6. I put 5 litres in to start as the reserve and then added 5 lots of 11 litres to make up 60 litres. I had a major scare with the Strato as the settings disappeared after I turned it off and back on again. At first I thought I had to pull the Strato out and replace the internal lithium battery but an email to Matt at MGL support told me that there is a small glitch in the software causing this and all I had to do is change another setting before I power off and my fuel settings will be saved. I have since upgraded the firmware and this problem has been fixed.

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My antennas mounted on the front floor. The front one is for the Air band (VHF) which is helical wound about 28 cm long and the rear one is a 1/4 wave for the 70 cm amateur band (UHF),I thought I would check their tune before I put the floor on. The 1/4 wave 70 cm one came up OK but the VHF air band one is not wonderful, but should be fine we are not looking for long range communications here just a nice clear local signal. A crimp on BNC connector , I dug out my crimper for this job , haven't used it for years.

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A slight diversion to break the cycle. A good use for a bit of left over channel , My knee board. All I have to do now is learn to write with my left hand. The next shot is my CHT sensor on CYL 5. They are designed to go under the spark plug BUT (There is always a but) they don't fit as there is not enough space around the plug in a Jabiru engine to fit them in. I put them under a head bolt very close to the spark plug so it should give me meaningful data and best of all won't need to be disturbed every time I remove a spark plug .Not so easy with CYL 6 though. The fins are bigger and the sensor would not fit all the way in. To solve this problem I unsoldered the wire off the terminal and re soldered back about 1/2" , luckily the terminal is long enough for this and now goes in OK. Just a note , these are not soft soldered connections but silver solder, requiring a gas torch to complete the job.>

The next problem, the cooling ducts will now need to be modified to clear the CHT sensor wire. Nothing is ever simple. On a positive note I re-tested the sensor in 100 deg c water and the output is OK. (It's 30 Micro volts per deg C) So at 100 deg C you get 3 mv.

Last shot the EGT sensors installed in the exhaust pipes with a couple of grub screws (Only one installed) to make sure it does not move and some anti-seize to make sure I can get it out later. The welding was done by a local welder JJ & MA Welding. I had to give him a plug as he did a good job AND as it turns out a fellow aviator.

With all the sensors connected into the RDAC and powered up they all are doing what I would expect. The EGT , CHT and Oil Temp all show ambient temp within a couple of degrees of my workshop thermometer. The fuel level and pressure are zero and the Tacho shows zero so I am quietly confident at this stage that it will all work.

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Another diversion. My GPS mounting system. I did not want any permanent attachment on the Sonex for this as I believe we will be wearing these on our wrists soon anyway. I have 5 different types of GPS receivers , from moving map, full Jeperson data base to basic. I have flown with them all many times and I have decided that simple is best hence the little Magellan Explorist 100 I picked up on E Bay for $100 is brilliant. I really only need 3 pieces of information when flying. Bearing Distance and ETA anything else you want can be easily worked out or read from a map. The Explorist gives this on one simple screen.

New warning light electronics and a new much inproved fuel pressure gauge.

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The origional electronics for my warning lights. Instead of installing another fuel and oil pressure sensor to switch the warning lights I built a couple of circuits to monitor the voltage on my existing sensors. I have set them to switch the LEDS at a point where the switches would operate. 1 PSI for the fuel and 10 PSI for the oil. Actually there are 3 circuits in the box , the third one is for the alternator warning light , somehow I managed to fry the existing circuitry in the regulator which is potted and I could not fix it. I built a voltage sensing circuit to switch off the LED when the battery voltage rose above 13v.

The third shot is it mounted on the fire wall minus the circuit board. I should have drilled the PCB mounting holes straight, I will build another one with straight holes and use this one as my spare. The last shot is a test plug I made to test the lights if I have a problem. By pluging in the test plug all the lights come on.

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My new system which is actually MKIII , MKI as described above had a few issues I was not happy about. Firstly the alternator warning light went out as soon as I started the engine and the battery voltage rose above 13v but when I shut down or turned off the alternator the LED would stay on for ages , till the voltage dropped below 13. Not much good as a warning light. I tried to improve this by increasing the switching voltage to 13.8 but the light STILL took ages to come on after switch off. SO on MKIII I reproduced the circuit inside the regulator (As described in the Jabiru installation manual plus one capacitor) , this works exactly how I want.

The next problem was with the fuel pressure gauge. Not with my interface but the Stratomaster display. It was a bit useless , the minimum full scale setting I could get was 7 psi AND the increments were 2 psi. Can you believe it I had 1 , 3 , 5 and 7 PSI and nothing in between. SO on MKII I discarded the gauge and just went with my LED.

One other change on MKII was the oil pressure warning light. I moved it to a dual switch bought from Jabiru. It has two terminals one for the gauge and the other for the warning light.

The new fuel pressure gauge.

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I rearranged my panel and reprogrammed the pressure gauge. Instead of a full scale setting of 7 psi, I set it to 50 and ignored the fact there is no decimal point. With a little bit of tweaking to my origional interface circuit I now have a gauge that reads 0 to 5 psi in 0.1 steps (If you ignore the lack of the decimal point.) AND the best part is I STILL have my warning LED which comes on when the pressure falls below 1.5 psi.

Nothing is ever perfect it seems as it does not go to zero when there is no pressure but 0.7 , I can live with that.

The reading of 27 or actually 2.7 psi is with the electric pump running. I have since adjusted that to 2.5 psi which is what my mechanical gauge claims the electric pump pressure is.

The pressure sender saga 19th February 2009.

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I spent a huge amount of time looking for a suitable fuel pressure sender. My first attempt was the one on the left purchased from Wicks. The 15 -30 psi labeling worried me as it was advertised as suitable for a Jabiru engine which runs about 2.5 psi so I contacted the supplier and they assured me that 15 - 30 psi means 0-15 psi or 0 - 30 psi I thought this a rather odd way of describing it but I took their word and ordered one. It arrived and I installed it on the Jabiru. Using my electric fuel pump to get some pressure I was presented with zero output.I removed the sensor and made up a variable pressure supply and connected my sender to it. Low and behold no output below 15 psi and it tops out at 80 psi. What we have here is an oil pressure sender totally useless for measuring fuel pressure in my application. Might be OK on fuel injected systems that run much higher pressures.

The next thing I discovered is there is no warranty on senders so I am stuck with it. And , out of pocket $50 aus.

I found another manufacturer that makes a 0 - 7 psi sender, UMA inc. So once again I went ahead. After much delay and messing around it finally arrived. The part number for this unit is N1EU07G you notice they sent me a N1EU70G which is a 70 psi version , totally useless to me. The worst part is they are not answering their emails so at this stage I STILL do not have a suitable sender. I am NOT happy.

I have since found a local source and have purchased a 0-7 psi sender. All I have to do now is try to get a refund on the second one. (Fingers crossed.) Got the refund! phew!

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Sender finally installed and working. Just have to get it talking to the Stratomaster.

Once I got the sender in I put some fuel in my auxiliary tank and turned on the electric pump to pressurize the system and see if I had any leaks , also to check the output of the sender. I am happy to report everything is as dry as a bone and the pressure came up to 2.5 psi which corresponds to about 2 volts output on the sender..

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Sensor saga update 21st of June 2009

Fuel pressure sender problem STILL not solved. I connected the sensor to the Strato as per the instructions and nothing. I disconnected it and checked the output with a voltmeter and nothing. (My sensor was toast) Back to the supplier and they agreed to send me another one free of charge. It turns out it is NOT possible to connect them directly to the Strato you need an interface which they supply free of charge. But the new one I am being sent CAN be connected directly. It get worse. The new one arrived and I installed it. Output OK and the Strato can see it. The reading is not wonderful as the Strato only reads 1,2,4 psi. But at least I had a reading. Not out of the woods yet. The next problem I discovered , when I turn off my pump and let the pressure dissipate the sensor reading stays up for about an hour. Not much good for an early warning system. So back to the suppliers who got back to the manufactures and I discover they have put too much silicon grease sealant in there and it's upsetting the pressure sensing element inside the unit. The manufactures have promised to send me another one that HAS been tested but at this stage nothing. I am past being NOT happy.

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The 23rd of June 2009 fifth sensor arrived.

I excitedly took it out of the box only to find it is a 0-35 PSI sensor. Ahhhhhhhhhhhh!! somebody up there does not like me. Back to the supplier , I am now waiting for my sixth sensor and my patients is getting thin.

The next sensor arrived , I connected it to the power and connected a voltmeter to the output wire. Powered up and the output is 12v all the time can you believe it. (Just as well I did not connect it to my RDAC or it may have damaged that.) I opened it up and just like all the others it's chock a block full of silicon grease.

That's it I give up , I can only assume UMA inc don't make a working sensor. I have asked for my money back. I might make myself a pressure switch that operates the warning light and leave it at that.

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A pressure sensor from Aircraft Spruce for $40.00. 26th August 2009

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Winston Churchill said "NEVER GIVE UP" so I did not.

I found a pressure sensor at Aircraft Spruce that is a 0-16 psi sensor , for $40 ,I though I would try it out. It is a resistive type that's suits the Stratomaster. It is 240 ohms at rest and 166 ohms at 2.5 psi. With a single transistor interface it matches up with the Strato and my warning light circuit. "AND IT WORKS"

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HALLELUJAH !!!!!

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The Tachometer hook up 17th April 2009.

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I have always planned to connect my tacho to the Jab alternator , but I had read people are having problems with this method. Not to be deterred I went ahead and tried it. (Not with the engine running but with a 30 v ac supply connected to the regulator.) Sure enough the reading was low to start and faded away after a few minutes. After a bit of investigation the reason became clear. The RDAC wants a positive pulse to trigger the tacho circuit and the return path for this signal is via the switching SCR's that control the battery current / voltage. When the battery is receiving charge the SCR's are firing more frequently providing a return path for the tacho signal but when the battery becomes charged the SCR's only fire occasionally so the tacho stops.

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Even when the battery is taking a charge the SCRs' are not firing all the time so the tachometer reading is way lower than it should be due to the missing pulses.

I have 2 possible solutions , first one is a trigger circuit that takes negative pulses from the alternator ( These always have a return path via the two normal diodes in the bridge.) The trigger circuit then switches positive pulses to the RDAC using the battery supply. This setup works fine as you can see in the photos. I am using a setting of 15 pulses per ten rpm so with a 50hz supply (Australian mains frequency) I get a reading of 2000 rpm , well almost it jumps around a lot. I think those pesky SCRs' are still upsetting things. When using the direct connection with the battery on charge the reading is not even close to accurate and it does not matter which side of the alternator you connect it to , same result for the same reason.

The second and simpler method is using a small 1 to 1 audio transformer. Connect the primary winding directly across the alternator and one side of the secondary to ground and the other side of the secondary to the RDAC. I put a 5k resistor in the primary circuit to reduce the current in the primary winding and hence the voltage in the secondary winding. The RDAC only needs a few volts to work. The alternator is rated at 40v. This system produces a much more stable reading and when I turn off my alternator on the panel the tachometer keeps working.

I have included the schematic for my trigger circuit in case you want to experiment with it , I did not find out why it jumps around so much. The transformer method is steady as a rock.

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My Re worded Warning placard.

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24th of April 2010 ,Yet another switch on my panel.

I have connected the Stratomaster warning signal to the headphones via a sub miniature toggle switch on the panel. If the warning signal sounds and alerts me to a problem , I don't want it to continue beeping in my ear. Particularly if I am doing an emergency landing.

I checked the signal with my oscilloscope and found it is a 0 to +5v square wave at 1 kHz , with a source resistance of 15 ohms or so. It will drive a small speaker but not with much volume. I connected it to the air band headphone circuit via a 100 ohm resistor, this does not effect the volume much but gives protection to the two output stages.

Last shot is the dropping resistor for the main fuel valve. The original was a 5w ceramic resistor and it got very hot even though it was only dissipating 2.5 watts. The new resistor is 20w and is connected to the panel for better heat dissipation.If you are wondering why I used this resistor , answer , because I have some.

Update on Tacho interface circuit 29th Feb 2012.

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I rebuilt the circuit on a small piece of veroboard to make it a bit more durable and at the same time try to address a problem. The tacho would stop as the engine approached idle (Due to the reduced output voltage and frequency from the alternator) I did some experiments with another transformer to see how much voltage I could apply to the primary without overheating it. First I did some calculations and to my surprise I could connect directly to a 40 volt 300 HZ source and it would only dissipate 1/4 of a watt and hardly get warm. No wonder it ran out of puff when the engine got below 1000 RPM as I had a 4.7 k resistor in series with the primary winding. I have included 2 100 ohm resistors one in each leg as a safety valve , much less than the 4.7k I had before so should be no problem at idle.

The calculations

The transformer is described 3K : 3K which means it's input impedance and output impedance is 3000 ohms. From this we can deduce it is a 1:1 transformer which means what ever AC voltage we apply to the primary winding we will get the same voltage at the secondary winding (Minus internal losses.) This impedance is dependent on frequency and the 3K is calculated at 1000 HZ or 1 KHZ. In my application the frequency will be 100 HZ to 300 HZ so the impedance will be 300 ohms to 900 ohms.

There is one other value that has to be considered here and that is the DC resistance of the winding. I measured this to be 280 ohms. Therefore if we are crusing along at 3000 RPM and producing 40 v RMS (From the Jab manual) we are applying 40 V at 300 HZ to the primary of our little audio transformer which has a total impedance of 900 + 280 ohms + my 2 100 ohm resistors, will = 1380 ohms. 40 V devided by 1380 ohms = 0.029 amps or 29 milli amps.

To calculate the power P = Current squared times the winding DC resistance. Answer 235 milli watts ,less than 1/4 of a watt.

The 2 pink wires are the alternator AC , I am feeding them into the cockpit so I can monitor the voltage just to see if the Jabiru manual is telling me the truth.

I know this is a lot of stuffing around for a semingly simple tacho interface. BUT if I overheated the transformer and started a fire in my engine bay while I was airbourne I would be a very sorry aircraft builder indeed.

18th August 2013 New CHT sensor location.

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I had been planning to do this for a while as the sparkplug location was rubbish , so for the first 50 hours I had it under a head bolt. Not as bad as the plug location but still not that satisfactory. Mr Jabiru has sanctioned the above location so I went ahead.

Feb 2017 Now we have a good location for the sensors I have added another 4 so I can monitor all the cylinders.

The CHT readout in in the bottom right hand corner now showing the 6 sensors. It has 6 horzontal bar graphs and the arrow points to the current cylinder temp being displayed. It was a hot day. It is interesting that the oil temperature gauge says 28 deg. My shed thermometer said 38.

I had a cabnet reshuffle to fit the bigger CHT display in. The RH has EGT and CHT the centre is Fuel pressure and Taco and the LH column is top Fuel level then Oil pressure and bottom is the Oil temperature.