How do 3W ignitions work?
03-06-2004, 05:43 PM
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RE: How do 3W ignitions work?
Why ? Just like all the rest, you plug a 4.8 volt battery into the red and black wires coming from the box, plug the 3 pin plug from the sensor to the circuit. and flip the prop..If the battery is good and the plug caps don't leak the spark to ground the engine starts.
03-06-2004, 06:58 PM
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RE: How do 3W ignitions work?
I am looking for the technical end of the ignition. What is the signal to the hall effect sensor and the same go for the spark plug ends? How do you check to see if the ignition is work right? I know its working if the engine is running, but if I am having problems how do I check to see if the end devices are working and also I would like to know what part or parts have gone bad!
03-06-2004, 08:34 PM
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RE: How do 3W ignitions work?
The 3-W ignition is not repairable, if you crack a plug cap they can be replaced, you can also get a seperate sensor for repalcement.
There is no way to test the ignition so you just replace parts untill it works.
There is no way to test the ignition so you just replace parts untill it works.
03-06-2004, 09:24 PM
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RE: How do 3W ignitions work?
Holographic sensor? Wow man.....one too many sci-fi novels.
Actually, the 3W ignitions work on a smoke charge. Don't ever let the smoke leak out. If the smoke leaks out, they have to be sent back to 3W to be refilled with smoke before they will work again.
Actually, the 3W ignitions work on a smoke charge. Don't ever let the smoke leak out. If the smoke leaks out, they have to be sent back to 3W to be refilled with smoke before they will work again.
03-06-2004, 09:32 PM
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RE: How do 3W ignitions work?
Your best bet.........find someone who will etl you borrow their ignition to test. If it runs right, get new ignition modules. If it doesn't, check timing, tuning, etc etc etc. That would your best first step. Without a description of the problem it's hard to give you any suggestions.
Neo
Neo
03-06-2004, 09:36 PM
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RE: How do 3W ignitions work?
Can't you take the plug out and look for the spark? Excuse me if that's a dumb question. I ask my share.
I mean see the spark when you flip the engine over, of course.
I mean see the spark when you flip the engine over, of course.
03-06-2004, 10:35 PM
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RE: How do 3W ignitions work?
At the risk of being SERIOUS here. . . . .
Youc an check to see if the basic ignition itself is operating by turnign it on and off and watching for spark at the plugs. Watch BOTH plugs. Basically, pull the plugs out of the engine, insert them into the plug leads, and then turn the ignition on an off quickly. You should see some spark. This indicates that the basic Capacitive Discharge circuit, and coils, are working properly. This is considered an ignition "Output side" test, because it tests the output circuitry, but not the triggering/timing parts of the unit.
The "Input side" of the ignition is "triggered" by an inductive pulse from the pickup coil that is mounted on the engine. Basically, the very strong magnet mounted int he crank hub causes an inductive spike in the pickup coil, which triggers the control transistor to turn off (or turn on, depending on the actual circuit design) the voltage that has been saturating the coils, at the same time allowing the CD circuit to discharge, causing a fast collapse of the coils and causing the spark. If the pickup has gone bad, OR the magnet is weak, the triggering tranistor will not receive a strong enough signal, and will not switch the voltage on and off as it should.
Usually, these ignitions are basically bulletproof, and rarely fail. The worst culprit for them not firing is either the magnet in the hub getting too hot and losing it's strength, OR the pickup beign damaged in some way, though I've never seen a damaged pickup. They DO draw a lot of instantaneous current, though, so if the switch, or a connector, is degraded and not allowing a good amount of current to flow, you will not get enough powr to create a proper spark, leading to no-start or misfire conditioins. You CAN use a 5-cell pack, which gives a hotter, more visible, spark, for testing, and I run one in the plane using a 6 volt regulator, so that the ignition gives a hotter spark. This will make it easier to see the spark to ascertain if it actually exists.
Hope this helps. Aircraft International or Cactus Aviation, or even Desert Aircraft, are all good sources for further information should you need it.
Youc an check to see if the basic ignition itself is operating by turnign it on and off and watching for spark at the plugs. Watch BOTH plugs. Basically, pull the plugs out of the engine, insert them into the plug leads, and then turn the ignition on an off quickly. You should see some spark. This indicates that the basic Capacitive Discharge circuit, and coils, are working properly. This is considered an ignition "Output side" test, because it tests the output circuitry, but not the triggering/timing parts of the unit.
The "Input side" of the ignition is "triggered" by an inductive pulse from the pickup coil that is mounted on the engine. Basically, the very strong magnet mounted int he crank hub causes an inductive spike in the pickup coil, which triggers the control transistor to turn off (or turn on, depending on the actual circuit design) the voltage that has been saturating the coils, at the same time allowing the CD circuit to discharge, causing a fast collapse of the coils and causing the spark. If the pickup has gone bad, OR the magnet is weak, the triggering tranistor will not receive a strong enough signal, and will not switch the voltage on and off as it should.
Usually, these ignitions are basically bulletproof, and rarely fail. The worst culprit for them not firing is either the magnet in the hub getting too hot and losing it's strength, OR the pickup beign damaged in some way, though I've never seen a damaged pickup. They DO draw a lot of instantaneous current, though, so if the switch, or a connector, is degraded and not allowing a good amount of current to flow, you will not get enough powr to create a proper spark, leading to no-start or misfire conditioins. You CAN use a 5-cell pack, which gives a hotter, more visible, spark, for testing, and I run one in the plane using a 6 volt regulator, so that the ignition gives a hotter spark. This will make it easier to see the spark to ascertain if it actually exists.
Hope this helps. Aircraft International or Cactus Aviation, or even Desert Aircraft, are all good sources for further information should you need it.
03-06-2004, 11:52 PM
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RE: How do 3W ignitions work?
oh, the use an coil as the sensor?... I assumed when I read holographic sensor that someone was genuinely confusing the term for a "hall effect sensor" - which I assumed is what would be used in an electronic ignition.
03-07-2004, 12:07 AM
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RE: How do 3W ignitions work?
Actually, Jim, the coil also acts as an "Ignition Advance" control, because the faster the magnet passes by the coil the faster the rise time and subsequent triggering of the ignition. There is about 10-12 degrees of advance from about 1800 rpm to 4000-4500 rpm, all caused by the coils characteristics andhow strong the magnet is.
03-07-2004, 01:25 AM
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RE: How do 3W ignitions work?
I don't know about 3W and DA, but mine fires each time the magnet passes the Hall switch, doesn't matter if it's 1 rpm or 10,000..there is no delay or advance unless I put a syncro spark module in series with it...A timing light on the spark plug wire shows the prop stationary at any rpm, changing as the throttle is advanced or retarded when the syncro module is connected, not moving at all without the syncro module...The sensor on a 3W uses only 2 of the three wires in the plug, the black and white..A 3W sensor won't trigger mine or C&H's circuit, although TKG says he can make it work...Don't know about the new style 3W sensor, it might be a Hall, the old one definitely is not....
03-07-2004, 07:30 AM
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RE: How do 3W ignitions work?
That's the basic difference in ignition designs, RCIgn. First off, the polarity of the magnet is reversed between a Hall Effect and Pickup Coil style ignition (at least in the designs I've seen) Secondly, the basic ignitions themselves use the same basic circuit designs (okay there are minor differences. . . ), but each is triggered by a wave form of some sort. A Hall Effect switch gives an almost vertical ON signal, so in effect you get "hey it's ON" to the ignition box, and it fires. But on with a pickup coil gives a more sinusoidal signal occurs and becomes more squared off as the inductive energy of the magnet increases with the rpm. This effectively moves shortens the "On Ramp" trigger point induration, because the faster you go, the faster the rise time of the signal, and ther earlier this critical voltage will occur (not to mentioin MORE voltage will be produced).
As for the "New Style" Tachometer drive ignitions that 3W is marketing, it's basically two ignition circuits in one box, the one driving the coils and firing the plugs using the same "pickup coil" as before, and the same polarity magnet as every other 3W, and the "tach side" of the box using a reversed polarity magnet and the Hall effect switch. This requires two magnets in the hub, a good distance apart from eachother, and two pickups in the pickup assembly, one Hall Effect (for the tach) and the other Inductive (for the coils). Why didn't they just use one pickup and design a different circuit? I have a theory, but involves a close examination of the German language, and how Germans, in general, engineer things. I call it the "German Add-on tendency", and see it quite often in the German cars I repair every day.
Personally, my FAVORITE type of ignition for our models is the Reichmuth that D&B uses, which has two Hall Effect pickups that basically set up a timing "window of opportunity", and a timing/reference circuit begins advancing the timing at a set rpm, up to a maximum advance close to the first trigger point (First Hall Sensor), and at idle use only the second trigger point as your base idle timing. Granted, the ignition could use some refinement, but I like the concept. It's much simpler in concept than a "delay circuit", and I personally prefer the accuracy of a Hall Effect compared to an auto advancing inductive pickup style of ignition.
As for the "New Style" Tachometer drive ignitions that 3W is marketing, it's basically two ignition circuits in one box, the one driving the coils and firing the plugs using the same "pickup coil" as before, and the same polarity magnet as every other 3W, and the "tach side" of the box using a reversed polarity magnet and the Hall effect switch. This requires two magnets in the hub, a good distance apart from eachother, and two pickups in the pickup assembly, one Hall Effect (for the tach) and the other Inductive (for the coils). Why didn't they just use one pickup and design a different circuit? I have a theory, but involves a close examination of the German language, and how Germans, in general, engineer things. I call it the "German Add-on tendency", and see it quite often in the German cars I repair every day.
Personally, my FAVORITE type of ignition for our models is the Reichmuth that D&B uses, which has two Hall Effect pickups that basically set up a timing "window of opportunity", and a timing/reference circuit begins advancing the timing at a set rpm, up to a maximum advance close to the first trigger point (First Hall Sensor), and at idle use only the second trigger point as your base idle timing. Granted, the ignition could use some refinement, but I like the concept. It's much simpler in concept than a "delay circuit", and I personally prefer the accuracy of a Hall Effect compared to an auto advancing inductive pickup style of ignition.
03-07-2004, 03:30 PM
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RE: How do 3W ignitions work?
Our hall switch can be used with any polarity magnet. One side will trigger off N pole and the other side will trigger off the S ploe. No big deal.
03-07-2004, 05:52 PM
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RE: How do 3W ignitions work?
I agree, I am trying to trouble shoot a problem with my ignition. I have taking out the plug and turned over the engine and the the plugs, but not all the time and sometimes only one plug will fire and not always the same one. That is why I am looking for the technical background on the ignition. I what to figure out if the sensor is bad or the magnet or ignition box. I don't want to have to buy the hole system if only one part is bad.
03-07-2004, 07:33 PM
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RE: How do 3W ignitions work?
I thonk the older 3-W systems have a mininum rpm. You should try seting everything up and spinning the engine with a regular starter.
Slso do it in the dark as the 3-W spark is sorta small.
Slso do it in the dark as the 3-W spark is sorta small.
03-07-2004, 08:12 PM
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RE: How do 3W ignitions work?
3Dpsycho, if you are getting a spark, sometimes, it's possible, as TKG said, that you do not have enough speed on the hub to generate sufficient signal to fire the plugs off in a static situation. Take a drill and spin the motor over, no plugs in it, and watch for spark at the plugs, Theyshould spark. . period. If in doubt, try a freshly charged 5-cell pack of at least 1500 ma capacity. Also, check to make SURE you are getting ALL the voltage to the ignition, as degraded contacts on a switch or connector may be the problem. If it STILL does not spark after all that . . replace it. Simple as that.
03-08-2004, 08:44 AM
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RE: How do 3W ignitions work?
Kris, I have tried everything that you have talked about days ago. That is why I started up this thread! I am trying to figure out if the hall effects is not sending a signal or is the ignition box just bad and in need of a replacement. OK, I have a hot 4.8volt 1700 ma. The battery was tested with a 1 amp load set of test lead and is reading 5.3 volts and after the switch going into the ignition I have the same voltage. I have turned the engine over with a fast starter with the spark plugs removed and laying up on the jugs. As you know I at this point have no compression, so the engine is able to free wheel. The spark is as I said in my last reply. I'd like to know do I replace the hole system or is the hall effect bad or the ignition box. That is why I am looking for the technical end of this question. How to test the sensor? How to test the plug end to find out if the ignition is bad? Thank all of you fly boys for your help!
P.S. Can the system be tested and how is it tested?
P.S. Can the system be tested and how is it tested?
03-08-2004, 09:36 AM
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RE: How do 3W ignitions work?
Okay, 3D. . short and sweet, you SHOULD be able to rock the hub back forth under the crank pickup and get a spark. . period. I do this with every ignition I have and it FIRES. If it will not fire, on a consistent basis, by doing the "rock across the top" test, but WILL spark when spun FAST with a drill, you have either a bad pickup coil or magnet.
Best way to check the pickup coil is with an Ohmmeter. I just checked 4 3W pickups and 2 DA pickups.
The 4 3W pickups ohmed at : 275, 245, 238, and 285 ohms . . .the Two DA pickups ohmed at 245 and 315 ohms. Since both pickups will fire off either ignition (DA or 3W, merely change the connector and observe polarity) yours should fall within this range of about 240-325 ohms. If your pickup is outside that range by a significant amount, sayy., . below 200 or above 400 ohms, I'd get it replaced.
To check the magnet in the hub, try to hang a hobby knife from it, using the blade of the knife. If the Knife will hang, it's good, if not, it's bad. . period.
If these two components pass these tests, you more than likely have a bad ignition box.
Not exactly rocket science, but it works.
Best way to check the pickup coil is with an Ohmmeter. I just checked 4 3W pickups and 2 DA pickups.
The 4 3W pickups ohmed at : 275, 245, 238, and 285 ohms . . .the Two DA pickups ohmed at 245 and 315 ohms. Since both pickups will fire off either ignition (DA or 3W, merely change the connector and observe polarity) yours should fall within this range of about 240-325 ohms. If your pickup is outside that range by a significant amount, sayy., . below 200 or above 400 ohms, I'd get it replaced.
To check the magnet in the hub, try to hang a hobby knife from it, using the blade of the knife. If the Knife will hang, it's good, if not, it's bad. . period.
If these two components pass these tests, you more than likely have a bad ignition box.
Not exactly rocket science, but it works.
03-15-2004, 02:39 PM
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RE: How do 3W ignitions work?
Thanks Guy's for all the help! Here is what I how know. I sent my ignition off to Cactus Aviation and they said that the ignition was fine, so I had Bobby send me a new coil and a new magnet. When I got the new set I tested the magnet. I used a "T" alien, one of the kind with the heavy rubber handles. The new magnet pulled the alien out of my hand when I got within a 1/4" from it and the one that is in my back plate wouldn't hold the alien even when I put it next to it. So I changed out the magnet and all is fine. Thanks Again!
