Transistor trick for 2GCDFIS.
06-08-05, 01:13 PM
#101
Okay, I performed some bench testing last night using the fixed pulse width addition. I added a MC14538 retriggerable monostable (configured both in retriggerable and nonretriggerable forms) and used a couple different resistor/capacitor combinations to get output pulses in the 2 to 3 ms range. With this setup, I experienced no heating of the 2nd gen igniter (stayed quite cool) and was able to eliminate the second transistor and drive the 2nd gen igniter directly from the MC14538. This chip can sink/source 10ma, but the 2nd gen coil only requires less than 5ma. Also, since the second transistor is eliminated, the output voltage can swing fully to 5v instead of being limited to 4.3 to 4.4 volts because of the transistor follower. The only obvious problem that I can see is that we need to decide the optimum pulse width. We want it to be long enough to get the best spark possible, but if we set it too long the spark will cut out at high rpm (incoming signal faster than the output pulse width).
For instance, a 2ms pulse would limit you to below 15,000 rpm, 3ms would limit to below 10,000 rpm, 4 ms would limit to below 7,500 rpm. If we went with this setup, I think we would want to be in the 2.5ms to 3ms range. With this setup, the pulse width to the 2nd gen igniter is fixed, so the 1st gen igniter just triggers the circuit and has no control over the spark duration. I am not sure if there would be any problems with this or not.
If anyone has input, it would be appreciated.
Kent
For instance, a 2ms pulse would limit you to below 15,000 rpm, 3ms would limit to below 10,000 rpm, 4 ms would limit to below 7,500 rpm. If we went with this setup, I think we would want to be in the 2.5ms to 3ms range. With this setup, the pulse width to the 2nd gen igniter is fixed, so the 1st gen igniter just triggers the circuit and has no control over the spark duration. I am not sure if there would be any problems with this or not.
If anyone has input, it would be appreciated.
Kent
06-08-05, 02:15 PM
#103
Not sure what the limitation of the stock dizzy is. I am sure that the signal would be cleaner and probably go to a higher rpm since it doesn't have to fire the coil directly (much less load on the 1st gen igniter).
What I am saying is that this portion is added to the current circuit. When the 1st gen igniter fires (falling edge), the MC14538 will output a fixed pulse (based on the resistor/capacitor values you connect to it). It doesn't care out the incoming pulse width. It can be longer or shorter than the output pulse width. The problem is that since the pulse width is fixed, at high rpm, the trigger from the 1st gen igniter will be faster than the output pulse with. Above this point, you will get no spark at all (guess we could think of it as a built in rev limiter).
I think that if we set the pulse to be about 3ms or a bit less (10,000 rpm max) would maybe be a good value. I would like the value set so that the rpm limit is much higher than what people may typically rev to. I just wonder if there may be any other problem associated (the ignition end) with running a fix pulse. I know the electronics and the coil/igniters can handle it (runs much cooler than using the pulse width produced frm the J-109). I just wonder if there is some combustion consideration in all this.
What I am saying is that this portion is added to the current circuit. When the 1st gen igniter fires (falling edge), the MC14538 will output a fixed pulse (based on the resistor/capacitor values you connect to it). It doesn't care out the incoming pulse width. It can be longer or shorter than the output pulse width. The problem is that since the pulse width is fixed, at high rpm, the trigger from the 1st gen igniter will be faster than the output pulse with. Above this point, you will get no spark at all (guess we could think of it as a built in rev limiter).
I think that if we set the pulse to be about 3ms or a bit less (10,000 rpm max) would maybe be a good value. I would like the value set so that the rpm limit is much higher than what people may typically rev to. I just wonder if there may be any other problem associated (the ignition end) with running a fix pulse. I know the electronics and the coil/igniters can handle it (runs much cooler than using the pulse width produced frm the J-109). I just wonder if there is some combustion consideration in all this.
06-08-05, 08:06 PM
#104
Rotary Enthusiast
Kent,
Did you get my reply to your PM yesterday? I answered a bunch of your questions and posted the test results you were looking for.
Don't use the signal pulse width for max rpm determination, but the coil charge time, which is related but not equal. See the PM for results table. From my testing any IgT pulse longer than 2ms will result in the ignitor driving in current limiting mode, causing ignitor heating, and creating no increase in coil energy. Note that those results I sent you were from tests done at battery voltage, about 12.6V or so. In a running engine system voltage is a volt or two higher meaning the limit will be reached even sooner.
I'd suggest 2ms is a good choice, which results in a coil charge time of about 4.0ms. Any longer than that, and discharge time at high rpm is severely limited, meaning the coil doesn't get enough time to fully discharge before starting to charge again, reducing the maximum spark energy.
It'd be nice if someone would scope the IgT line on a stock FC, and log data during cranking, at idle, and a few operating points across the typical rpm/load map to see if the oem ecu is sending fixed or variable pulse width IgT commands to the ignitor during these operating modes.
Congrats on the successful circuit design work. It sounds like once the desired pulse width is known, it should be pretty straightforward to build an FB->FC adapter circuit. An added plus would be that those FB ignitors should last much longer given they are no longer driving a coil.
Roger.
Did you get my reply to your PM yesterday? I answered a bunch of your questions and posted the test results you were looking for.
Don't use the signal pulse width for max rpm determination, but the coil charge time, which is related but not equal. See the PM for results table. From my testing any IgT pulse longer than 2ms will result in the ignitor driving in current limiting mode, causing ignitor heating, and creating no increase in coil energy. Note that those results I sent you were from tests done at battery voltage, about 12.6V or so. In a running engine system voltage is a volt or two higher meaning the limit will be reached even sooner.
I'd suggest 2ms is a good choice, which results in a coil charge time of about 4.0ms. Any longer than that, and discharge time at high rpm is severely limited, meaning the coil doesn't get enough time to fully discharge before starting to charge again, reducing the maximum spark energy.
It'd be nice if someone would scope the IgT line on a stock FC, and log data during cranking, at idle, and a few operating points across the typical rpm/load map to see if the oem ecu is sending fixed or variable pulse width IgT commands to the ignitor during these operating modes.
Congrats on the successful circuit design work. It sounds like once the desired pulse width is known, it should be pretty straightforward to build an FB->FC adapter circuit. An added plus would be that those FB ignitors should last much longer given they are no longer driving a coil.
Roger.
06-08-05, 09:48 PM
#105
No, Roger. I didn't receive your pm. I thought most of the problems with the forum were worked out, but I guess there are some bugs still left. If you have a copy in your sent messages, please try to re-send. I am sure that it will have lots of useful information. I have experience with building circuits and getting them to do what I want, but I have been pretty clueless on the actual ignition systems until now (especially the 2nd gens). Thanks for posting your input. It is really appreciated. Want to have a good idea what will work before reconstructing the circuit that I already have.
I'll go for a 2ms pulse as you suggested. I have tried 3ms as well and there wasn't really any heating of the igniter as I was previously experiencing. The only problem is the upper RPM cut-off as mentioned. The numbers that I were giving were the point that the circuit would fail to retrigger itself (next input pulse occurs during the previous output pulse). The actual pulse will vary somewhat from 2ms because the timing is set with an RC circuit. The tolerance in the capacitor is what will throw it off the most (up to 10% or so).
I agree that it would be nice to see what the FC does as far as the IgT signal. It would probably be difficult to make it variable for our case. The other option I was thinking of was limiting the pulse width (let the first gen igniter control up to a certain point, then fix the value above that). The only problem is that we would probably have to add a clock circuit, counter, and maybe a couple flip-flops to make it work. I think the constant 2ms pulse will work well for us.
Kent
I'll go for a 2ms pulse as you suggested. I have tried 3ms as well and there wasn't really any heating of the igniter as I was previously experiencing. The only problem is the upper RPM cut-off as mentioned. The numbers that I were giving were the point that the circuit would fail to retrigger itself (next input pulse occurs during the previous output pulse). The actual pulse will vary somewhat from 2ms because the timing is set with an RC circuit. The tolerance in the capacitor is what will throw it off the most (up to 10% or so).
I agree that it would be nice to see what the FC does as far as the IgT signal. It would probably be difficult to make it variable for our case. The other option I was thinking of was limiting the pulse width (let the first gen igniter control up to a certain point, then fix the value above that). The only problem is that we would probably have to add a clock circuit, counter, and maybe a couple flip-flops to make it work. I think the constant 2ms pulse will work well for us.
Kent
06-08-05, 10:12 PM
#106
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Man, this information still makes my head spin! LOL. I really need to spend some time studying the electronic world... You guys are making me feel like an uneducated fool!
Anyway, all that matters to me at this point is whether or not this will make my zoom zoom, zoom zoomier....
Anyway, all that matters to me at this point is whether or not this will make my zoom zoom, zoom zoomier....
06-08-05, 10:40 PM
#107
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Originally Posted by gsl-se addict
This is the circuit that I am currently running.
The tolerances for this portion don't really matter. I used standard 5% 1/4W resistors. The transistors are not real critical either. Any general purpose NPN transistor will work (2N2222A, 2N3904, 2N5401, etc.) The only thing I did a little different is I changed the pull-up resistor (near the LED) to 470 ohm instead of 1k. It doesn't really matter, but I did that to get the output pulse voltage a bit higher.
As I mentioned, this setup makes a very strong spark, but is creating a fair amount of heating of the 2nd gen igniter. I am going to try to limit the pulse width to try to reduce the heating but maintain the strong spark.
The tolerances for this portion don't really matter. I used standard 5% 1/4W resistors. The transistors are not real critical either. Any general purpose NPN transistor will work (2N2222A, 2N3904, 2N5401, etc.) The only thing I did a little different is I changed the pull-up resistor (near the LED) to 470 ohm instead of 1k. It doesn't really matter, but I did that to get the output pulse voltage a bit higher.
As I mentioned, this setup makes a very strong spark, but is creating a fair amount of heating of the 2nd gen igniter. I am going to try to limit the pulse width to try to reduce the heating but maintain the strong spark.
I have 2 questions
1 .should i put a heat sink on the nte960?
and 2. would i have to adjust the timing?
06-08-05, 11:04 PM
#108
The voltage reg shouldn't need a heat sink. It is only powering the transistors and the LED. Mine only gets slightly warm to the touch. You are welcome to try that circuit. It works pretty well, but you probably will experience significant heating at the base of the 2nd gen coil. This portion that I am adding should take care of that problem (haven't experienced any heat issues bench testing). You shouldn't need to do anything with your timing. The delay through the circuit should be small, but you could alway double check the timing to be sure.
Kent
Kent
06-08-05, 11:12 PM
#109
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Cool ! thanks Do U think the coil handle the heat? B/c the engine bay gets pretty hot and as U stated the coil is getting kinda hot.........Also i have to remove the 2nd gen igniter? or not?
06-08-05, 11:30 PM
#110
The 2nd gen ignitor stays in place. This circuit goes in between the 1st gen ignitor and the 2nd gen ignitor/coil pack. The output goes to tyhe red wire of the 2nd gen coil. The coil gets grounded though the mounting bracket and you need to supply the coil and circuit with switched 12v.
I have ran the last few days on this circuit with no problem. I am not sure how it would do over long distances or long term. The 1st gen ignitor appears to create a pulse width that is too wide. This puts the 2nd gen ignitor in its current limiting mode for much of the time causing excess heating. The coil itself stays cool, but the back gets pretty hot (from the ignitor). If we want to make sure this is reliable, we need to keep the ignitor within below whatever the design limit temperature is (the cooler, the better). The part that I am adding is pretty simple, but takes up a fair amount of space (16 pin chip). It has two monostable circuits on it, but we will only use one. I am trying to find one that is single and smaller. So far even the smaller ones still have 14 pins.
If you want, go ahead and build the circuit up to the 2nd transistor (volt reg, LED, input wiring, etc.) Just don't add the 2nd transistor yet. This portion that I am adding will likely take its place. If you have any questions, feel free to ask.
Kent
I have ran the last few days on this circuit with no problem. I am not sure how it would do over long distances or long term. The 1st gen ignitor appears to create a pulse width that is too wide. This puts the 2nd gen ignitor in its current limiting mode for much of the time causing excess heating. The coil itself stays cool, but the back gets pretty hot (from the ignitor). If we want to make sure this is reliable, we need to keep the ignitor within below whatever the design limit temperature is (the cooler, the better). The part that I am adding is pretty simple, but takes up a fair amount of space (16 pin chip). It has two monostable circuits on it, but we will only use one. I am trying to find one that is single and smaller. So far even the smaller ones still have 14 pins.
If you want, go ahead and build the circuit up to the 2nd transistor (volt reg, LED, input wiring, etc.) Just don't add the 2nd transistor yet. This portion that I am adding will likely take its place. If you have any questions, feel free to ask.
Kent
06-10-05, 12:49 AM
#113
Okay. Here is the modified circuit. It has one IC, one more resistor and one capacitor more than the previous design. I did some bench testing tonight and all seems to work well. The combination of the 22kOhm resistor and the 0.1 microF cap sets the pulse width to 2.2 ms theoretically. However, the pulse is slightly less as this IC produces pulses slightly less than the theoretical value at lower operating voltages (such as 5V). The capacitors typically have a 10% tolerance or so, so the value is not going to be exact, but will be pretty close. You can use a 20kOhm instead to get 2ms,but they are not as common.
Using this particular setup (2ms pulse), the coil stays cool (back of coil is only slightly warm to the touch). The coil continues to fire up to over 14,000 rpm. This is where the time between sparks is below the pulse width (2 ms). At these speeds, the coil continues to fire, but the spark will not be quite as intense because the coil charge time is more like 4ms or so. So above around 7500 rpm, the coil will not be able to fully charge before the next spark. I will add the modified circuit to my car probably this weekend.
Kent
Using this particular setup (2ms pulse), the coil stays cool (back of coil is only slightly warm to the touch). The coil continues to fire up to over 14,000 rpm. This is where the time between sparks is below the pulse width (2 ms). At these speeds, the coil continues to fire, but the spark will not be quite as intense because the coil charge time is more like 4ms or so. So above around 7500 rpm, the coil will not be able to fully charge before the next spark. I will add the modified circuit to my car probably this weekend.
Kent
06-13-05, 12:54 PM
#116
Well, I tried using the fixed pulse width and the coil still got fairly hot. It is strange because it didn't even get slightly warm when testing. I was thinking it may be a grounding issue. Right know it is just grounded though the mounting bolt that hold it on. Maybe I'll add a ground wire to see if it helps at all. I did measure resistance from the coil back to the battery - terminal and it was only 0.5 ohms.
It also didn't seem to run as well as before. I will try the ground thing and see if it helps, though. jayroc, lovintha7, and Kentetsu: I know you guys are anxious to do some testing. It would actually help me out so I know if the issues that I see are engine/mounting independent. What I can do for you guys is build a circuit that does both the fixed PW and the regular that I was running before. All that I would have to do is add a switch to bypass the 4538 chip. That way you guys can try it both ways to see what works better. If I can find an inexpensive rotary switch, I could also have the fixed pulse width mode adjustable (say 1 ms to 3 ms).
Kent
It also didn't seem to run as well as before. I will try the ground thing and see if it helps, though. jayroc, lovintha7, and Kentetsu: I know you guys are anxious to do some testing. It would actually help me out so I know if the issues that I see are engine/mounting independent. What I can do for you guys is build a circuit that does both the fixed PW and the regular that I was running before. All that I would have to do is add a switch to bypass the 4538 chip. That way you guys can try it both ways to see what works better. If I can find an inexpensive rotary switch, I could also have the fixed pulse width mode adjustable (say 1 ms to 3 ms).
Kent
06-22-05, 10:10 PM
#117
Just a quick update.
I haven't had time to do much testing at the moment. I have built circuits for jayroc and lovintha7 (they are on their way). I also am building one for Kentetsu which is nearly complete and then will be building one for TurboSE as well. This means that we will have at least 5 people testing this design out under different applications: Turbo, NA, 13B, and 12A. The circuit are being built with a switch so that it can go from the initial design where the J-109 controls the pulse width or can be switched to use the constant (2ms) pulse width mode.
I haven't added a switch to mine yet to switch between the two modes. However, I hooked up one of the circuits that I built for jayroc and lovintha7 to make sure they functioned correctly. I started the car on the variable pulse width mode. When I switched to the constant pulse width, there was a noticeable decrease in the idle speed. I switched back and forth several times to make sure it wasn't just a coincidence. Sure enough, the same thing happened each time. With the variable pulse width, the idle speed increased to over 950 rpm. With the fixed pulse width it was about 800 rpm. This reinforces what I noticed earlier (the fixed pulse mode seemed to have less power, rougher idle).
I will continue testing and keep the thread updated. It will be interesting to see what the others find as well.
Kent
I haven't had time to do much testing at the moment. I have built circuits for jayroc and lovintha7 (they are on their way). I also am building one for Kentetsu which is nearly complete and then will be building one for TurboSE as well. This means that we will have at least 5 people testing this design out under different applications: Turbo, NA, 13B, and 12A. The circuit are being built with a switch so that it can go from the initial design where the J-109 controls the pulse width or can be switched to use the constant (2ms) pulse width mode.
I haven't added a switch to mine yet to switch between the two modes. However, I hooked up one of the circuits that I built for jayroc and lovintha7 to make sure they functioned correctly. I started the car on the variable pulse width mode. When I switched to the constant pulse width, there was a noticeable decrease in the idle speed. I switched back and forth several times to make sure it wasn't just a coincidence. Sure enough, the same thing happened each time. With the variable pulse width, the idle speed increased to over 950 rpm. With the fixed pulse width it was about 800 rpm. This reinforces what I noticed earlier (the fixed pulse mode seemed to have less power, rougher idle).
I will continue testing and keep the thread updated. It will be interesting to see what the others find as well.
Kent
06-22-05, 11:01 PM
#119
I do, but it has just the fixed pulse width mode right now. It didn't run as well as I had it before, so I am using the stock ignition for the moment. I'll probably just rebuild mine when I get yours and Kentetsu's done. The circuit layout is cleaner now. I will add a switch to mine as well so I can try both modes out more. I may try making my fixed pulse mode adjustable. That way I can see if the fixed mode works better at some value other than 2ms.
As it stands now, the simple circuit (without the fixed pulse width) seems to work better. This can be seen by driving and the increased idle speed. The 2ms is maybe too short of a period to get a real strong spark at idle. The only issue (especially with the variable pulse width mode) is heating of the 2nd gen ignitor. I am not sure how warm they are suppose to get. I didn't get any helpful info from the 2nd gen forum when I asked.
As it stands now, the simple circuit (without the fixed pulse width) seems to work better. This can be seen by driving and the increased idle speed. The 2ms is maybe too short of a period to get a real strong spark at idle. The only issue (especially with the variable pulse width mode) is heating of the 2nd gen ignitor. I am not sure how warm they are suppose to get. I didn't get any helpful info from the 2nd gen forum when I asked.
06-22-05, 11:26 PM
#120
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What if If i mount the ignitor on a heatsink outside the FC coil?
Or i guess it'll be better to leave it inside and see how It works (lasts)
4 what i saw in the pictars.....That is a STRONG *** spark!!! Compared to the DLFDLIS one or 2nd gen direct fire........I'm preety sure it'll make a FAT difference in low end torque...
Or i guess it'll be better to leave it inside and see how It works (lasts)
4 what i saw in the pictars.....That is a STRONG *** spark!!! Compared to the DLFDLIS one or 2nd gen direct fire........I'm preety sure it'll make a FAT difference in low end torque...
06-22-05, 11:35 PM
#121
Yes, it sure makes a FAT spark, especially at higher RPM. It is fun to test it on the bench and crank up the rpm.
The base of the 2nd gen coil would probably be better than a lot of heatsinks just due to its size/mass. The 2nd gens do mount it on the inner fender. There is probably a fair amount of conduction of heat to the body of the car. It probably gets some cooling from the rad fan/forced air though the engine bay as well. Again, I am not sure how hot is hot as I have nothing to compare to. It may very well be that the temps that I am seeing are completely normal.
I should get Kentetsu's circuit done in the next day or two. I should be able to get yours knocked out this weekend.
The base of the 2nd gen coil would probably be better than a lot of heatsinks just due to its size/mass. The 2nd gens do mount it on the inner fender. There is probably a fair amount of conduction of heat to the body of the car. It probably gets some cooling from the rad fan/forced air though the engine bay as well. Again, I am not sure how hot is hot as I have nothing to compare to. It may very well be that the temps that I am seeing are completely normal.
I should get Kentetsu's circuit done in the next day or two. I should be able to get yours knocked out this weekend.
06-22-05, 11:40 PM
#122
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Thanks .....Should i test the Temp On a 2nd gen TII (my friends)
But i dunno if that Would be an accurate reading!
I'll use A snap on meter(blue point) automotive ....W/ a little temp sensor
and compare it to the SE one?
But i dunno if that Would be an accurate reading!
I'll use A snap on meter(blue point) automotive ....W/ a little temp sensor
and compare it to the SE one?
06-22-05, 11:52 PM
#123
If you could check out the TII one, that would be great. If you can get an actual temperature using a thermocouple, infrared temp sensor or whatever, that would be great. Measure the temp of the back of the coil pack. If you can't measure actual temp, try to at least feel the back of the coil after running awhile (maybe after a drive). See if it is hot to the touch. If so, how long can you touch it before needing to pull your hand away to avoid getting burned. I will see if I can find a thermistor or something and attach to the back of the 2nd gen coil back on mine. That way I should be able to get a reasonable measurement of temp.
07-01-05, 10:26 PM
#125
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Got my gizmo today Kent. Looks sweet. I'll keep you posted as I get it installed and tested. It may take a little while though because my wife sprained both ankles really badly and right now my life sucks as a result...