gsl-se addict

iTrader: (3)

Okay, I built the latest version of the circuit and it seems to be doing what it is suppose to. The current draw is about 100 mA with a 2n2222 to simulate the J-109 and with the voltage reg (7805) during firing and about 4.67 mA when not. I used 1k resistors for R3 and R5. This is when the circuit is powered with 12.25V. I haven't tried firing a 2nd gen coil with it yet as I don't have one. I will see if the local wrecking yard has a second gen (last time I checked it didn't). I will see if I can get a leading coil and maybe a 2nd gen fuse box. If they don't have one, I will get one off someone on the RX7Club.

There doesn't seem to be much of a problem with heating. Even with the circuit held in the firing state for several minutes, the components only got slightly warm to the touch.

Jeff: Do you know what auto part stores carry 2nd gen plugs? I know I can get them from Atkins, but it hardly seem worth it just for 2 spark plugs.

I will keep you informed on the progress.

Kent

Jeff20B

iTrader: (13)

Cool! Schuck's carries BUR7EQ (leading) plugs for a 2nd gen. You may have either Kragen or Checker in Oregon.

aGoGo

Oh, I just found out this thread, interesting things here. Analog design is an art I am not very familliar with how the ignition works on our car yet. Can someone tell me what's the output (Voltage, Waveform) from the J-109? It that correct all we are trying to do here is to step down the output of the J-109 while having enough driving power? If that's the case, what about an simple op-amp (lm741), for anything toggling even lower than 1kHz? Am I on track?

gsl-se addict

iTrader: (3)

Thanks, Jeff. Yes, we have Shucks here. The one in my town went out of business a couple years ago, but there is a Shucks about 10 mi from here. I will see if they have them in stock and maybe pick some up this weekend.

Yes, I think you are on track. Basically in the stock ignition, the J-109 pulls the coil (-) terminal down to ground causing it to fire. With the coil connected, the output would look something like the trace renns posted. Without the coil (using a resistor instead between the B and C terminals of the igniter), the waveform should be fairly square going from Vbatt when not firing to ground when firing.

The idea is to make a non-inverting circuit where the J-109 sees Vbatt and ground, while the 2nd gen igniter sees 5v and ground. One of the great things about electronics is there is usually 100 different ways to make a circuit do what you need. It is a matter of being creative in order to minize components, power consumption, speed, etc.

You may be able to use an op-amp for the job. The frequencies seen will be less than 300Hz for the most part. The problem is that I don't know if the 741 could source enough current for the igniter, since we don't really know the current requirements. You could use the 741 wired as an inverting amplifier with a gain of 1. The output could then connect to an NPN transistor (as we have done at the end of the circuit) to invert the signal back so the output will go from 0 to 5v. If you want to go the op-amp route, I could model the circuit up in PSPICE so that you can see how it would perform.

Kent

aGoGo

Well, a non_inverting scheme can be used and there is no need for an extra transistor, if it got enough driving power (20 mA ?). How many amps are you aiming for? Op-amps herite very low output resistance for the frequency range we are dealing with.

gsl-se addict

iTrader: (3)

I know that we could use a non-inverting scheme with the op-amp, but I said that it may not source enough current. The 741 can source a maximum of 25 mA. If you want an indicator, such as an LED (even though this is not needed), nearly half of the maximum source current would be used up. I don't know what the exact input requirements of the 2nd gen coil are (since I don't have one to test). The extra transistor would also make it easier to make sure the output is limited to 5v (although more shouldn't really hurt). If you do the non-inverting op-amp directly, the output is going to be some fraction (or multiple) of whatever the input voltage is (unless clipped by the rail voltage). In this case, a variation in Vbatt would cause a variation in the output voltage. This may not be a big deal, but it would be nice to try to simulate what the 2nd gen coil sees as close to the stock setup as possible.

You are more than welcome to give the op-amp circuit a try. If you have an idea of what you want, I could model it up for you if you would like.

Kent

aGoGo

You de Electrical Man? :p

aGoGo

Kent, I was just messing with ya, I got an old copy of Pspice too , I am not planning this mod yet, but seriously, if I were digging into this, I would do it straight up from the Dizzy. Have fun man. I will keep messing around here too

gsl-se addict

iTrader: (3)

I am not sure what you mean. Are you asking if I am an electrical engineer or something? My training is in nuclear engineering (nearly done with PhD), but I have taken several electrical engineering and electrical related physics classes. I have access to PSPICE, so it makes it real easy to model up circuits. Electronics is kind of a hobby for me. I enjoy doing projects such as this one. Especially since it relates to a RX-7.

EDIT: Just saw your new post. I was wondering what you were talking about. It's cool. I hope I didn't come across as a jerk, because really I am not. I am just pointing out some potential problems. Just keep thowing out ideas, that is what this thread is for. I am not saying this circuit is the best (it probably isn't), but it appears to work and is simple. Once we have done more testing, we should be able to see what works and what doesn't along with what improvements should be made. It would be nice to go straight from the dizzy and eliminate those expensive (when new) igniters, but we should get this going before we try to make that leap.

Op-Amps have a lot of nice characteristics. I looked a doing a design with them before going the transistor route. I am just not sure on the current requirements. That is why I went the transistor route. By adding the extra transistor on the op-amp circuit, the circuit is basically the same complexity as with just using transistors. I think that either way will work just fine. Like I said, there are usually 100 different ways to do something when it comes to electronics. There is not just one right way to do it.

When I get a second gen coil, I will try to do some testing on what the input current requirement are. That way we may be able to simplify the circuit some.

Kent

jayroc

I wanted to bump this thread to see how you guys were getting along with this new ignition design.

gsl-se addict

iTrader: (3)

The circuit itself seems to work, but I have been waiting on getting a second gen coil for the past couple weeks from a seller on the forum. If I don't get it soon, I will have to get a refund and get the coil elsewhere. I am very anxious to try it. The lack of having the coil is the only thing keeping me from trying it out. I think that the circuit should work nicely. I will post up results as soon as I get the coil put in.

Kent

gsl-se addict

iTrader: (3)

^ My post wasn't showing up from yesterday. Had to bump to get it to work.

gsl-se addict

iTrader: (3)

Sorry for the posts. Crazy forum wasn't displaying the whole thread.

Elysian

u can't find a 2nd gen leading coil at the bone yard? i know the import bone yard near me every single FC out there still has its coils in tact lol

gsl-se addict

iTrader: (3)

Well, I've already paid for the one that I'm waiting for and the wrecking yard here wants $60 for a leading coil. I could probably pick one up if I drove to Eugene or Salem for a decent price, but haven't had a chance.

Elysian

jeez i can get a leading coil for under 20 bux... i think when i was having a issue with my 88 TII i got the leading and trailing packs for 20 bux

GLC13B

Greeting ! I was hoping you could explain to me your experience with the (Direct fire if possible ?

gsl-se addict

iTrader: (3)

I haven't tried direct fire yet, still waiting on my coil. I have seen that you have asked about the direct fire setup in a couple of other threads. Basically what direct fire does, is:

1. Connects the coil(s) directly to the leading plugs. This eliminates the wasted spark energy and wear on the dizzy rotor/cap from going though the distributor.

2. Produces a second leading spark (late leading) at 180* later of the eccentric shaft. This will help complete combustion (probably won't add much if any power, but will clean up the exhuast some at least).

There are a couple ways to go about doing this:

1. DLIDFIS (Dual Leading Igniter Direct Fire Iginition). This is where you add a second 1st gen igniter with coil and fire the two coil together (one for each leading plug). You just need another igniter, coil, and some wiring to make this work.

2. 2GCDFIS (2nd Gen Coil Direct Fire Iginition). This is where you use a 2nd gen coil and trigger usually with the first gen igniter. The second gen coil has two output posts as the 2nd gen and later cars have direct fire from factory. This may be a little easy/cleaner to do than the DLIDFIS, but it all depends on what parts are avaliable to you.

3. 2GCDFIS w/ transistor trick. This is what we are trying to do here. In this case the 1st gen coil (with the addition of an additional circuit) will be used to trigger a 2nd gen igniter. The 2nd gen igniter will then fire a 2nd gen coil. The distributor and the 1st gen ignitor controls the signal (dwell, etc.) and the additional circuit conditions it to work directly with the 2nd gen igniter. In the 2nd gen cars, the timing is done by the ECU and the igniter is fired from a 5 volt square wave. Based on Jeff's experiences, the 2nd gen coil with the 2nd gen igniter has a much more intense spark than the 2nd gen coil fired directly from a 1st gen igniter.

There are a couple other ways to do it, but these are the main ones that us first geners deal with. There are certain advantages/disadvantges to each one, but they should all perform about equally. I will report on my experiences with the 2GCDFIS w/ transistor trick as soon as I get the coil and get it installed. I can't wait to try it.

Hope this helps.

Kent

Jeff20B

iTrader: (13)

That sounds about right, but let me clarify something. When you say "In this case the 1st gen coil" it may be confusing. I call the sensor thingies in the distributor either pickups or VR sensors (VR = variable reluctance). It depends largely on my state of mind at the time. Not everyone knows what a VR sensor is, but most could look in a dizzy and figure out which bits the magnetic pickups are.

GLC13B, this probably isn't the best thread to discuss the differences. Go ahead and make a new thread in this 1st gen section dedicated to discussing the best ignition options for your GLC. You'll get more responses than in the other subforum you already tried. Heck, I don't even have a 1st gen but I use this section when it comes to discussing projects using 1st gen parts, which DLIDFIS, 2GCDFIS (when using a 1st gen J-109 ignitior) and the transistor trick for 2GCDFIS employ. I also posted pics here of the recent port job I performed on an R5 13B that went into my REPU, in this section. The R5 plates are very similar to Y plates found in stock 1st gens, and have the same port shape and size and can be ported the same amount (as far as I know... knock on wood to avoid porting into the water jacket) so I knew it would be of value to the 1st geners here.

GLC13B

Kent, thank you for the clarification ! I was kind of confussed with all this info.

Jeff20, i will start another thread in the first gen section ! Thanks guys !

Hyper4mance2k

iTrader: (40)

don't forget about the best MSD_DIS

jayroc

I know how you feel about getting a 2nd gen coil. There's about 9 FCs between 2 yards up near where I live. Somebody got all their coils, too. Grrr..

gsl-se addict

iTrader: (3)

Jeff: I meant to say igniter. Guess I wasn't paying attention to what I was typing.

Just thought that I would give you guys an update. I received the leading coil and got the circuit wired up. It appears that my leading igniter is dead, though. I know it wasn't the circuit that killed it because the load from that circuit is much less than firing the coil and the circuit works fine off of the trailing igniter. I may try to swap the igniters around and see if I can get it running off of the 2nd gen coil tonight. The only thing is that my trailing igniter has been acting up for awhile (doesn't always fire when cranking). I can make some nice sparks from the 2nd gen coil by grounding out the C terminal of the circuit.

So if anyone has some spare igniters, let me know. I am interested in picking up at least a pair.

I now need to find a place to mount the coil. I have an SE so the AC and PS kind of gets in the way.

On a side note: I installed a 2nd gen fuse box this weekend. Works good and an easy swap. It's nice because replacement fuses are easy to come by and there are 2 unused spots for future add-ons (e-fan + ?).

Kent

gsl-se addict

iTrader: (3)

I think that I found the reason my leading igniter died. I got my B and C wires crossed going from the igniter to the circuit .

Okay, guys. I'm going to need some input from you (especially those that have experience with 2nd gen coils).

Experimenting with the circuit and checking out the wiring diagrams, it appears that we need to modify the circuit. Our circuit puts out 5v when the C terminal of the 1st gen igniter is at 12v (not firing) the ouput then goes to ground when the first gen igniter fires. Looking at the 2nd gen FSM, it appears that the trigger wire should have 0v normally and pulse (5v?) when firing. We could alleviate this problem by elimnating the first transitor of the circuit (making the circuit inverting). This way the output will be 0v when not firing and 5v when firing.

One thing that I have found is that there is a fairly low impedence between the B, C, and trigger lines of the 2nd gen coil and ground (several hundred ohms to about 1.2 kohms). This creates some problems. When testing with only the trigger wire connected (5v), the low impedence of the coil would pull the voltage down to 3v. When I applied 12v to the coil power, the trigger line would then increase to about 8v. We may need to add a voltage follower or something to isolate the circuit from the coil. The other option is to increase the value of the pull up resistors in the circuit (may hurt speed).

I als want to clarify the 2nd gen coil inuts.

Brown: Power (12v)
Red: trigger (0-5v)
Black: ?? Goes to the C terminal and coil (-) like it's for tach or something, but I don't see it shown on the 2nd gen wiring diagrams

Kent

gsl-se addict

iTrader: (3)

I went back to doing a single transistor circuit (inverting) with a 47k pull-up resistor and the coil seems to be firing much stronger now (bench testing). The output is low when the J-109 is not firing and then goes to the high state when firing. The circuit seems to work well, but the low input impedance of the 2nd gen coil is causing the high state to be at about 2.55v instead of 5v. The coil seems to be firing just fine with this setup though. I may have to add a voltage follower for isolation.

An op-amp would normally work nice for this, but they tend not to like the input to be near the - supply voltage (ground in our case). This option would work well if we had a split supply like +/- 12v. I will try to add a transistor follower or I could use a pair of CMOS inverters (usually used in digital electronics). This way we can have the output go between 0 and 5v hopefully without the input impedance of the 2nd gen coil throwing it off.

I will try to install within the next couple days (weekend at the latest) and let you all know how it performs. Just bench testing, I can tell you that coil throws some much longer sparks than a first gen coil does.

Kent