Pickup Coils/Reluctor

[mainlylinux]

Anybody have an idea of the AC voltage generated by the XS11 Pickup Coil during cranking and at redline?

This is what I have so far, but I haven't counted my rpms yet, and I doubt I can hit 8-10k rpms with this little fan motor

I don't want to get anyone's hopes up, because I'm not sure if this is a feasible project, but I'm looking at building a replacement TCI box. If I can do it I'll make the plans available here.

[randy]

Voltage should remain the same, only frequency should change with RPM's. Looks like you have enough gear to figure this out Let us know how it goes!

[mainlylinux]

Voltage

Actually testing is showing that the voltage is greater when the rpm's increase - I've followed up with a search of google to confirm this.

One of my main concerns is to keep the circuit as simple as possible while doing everything I want it to.

The reason to find out the min and max voltage of the pickup coil output is so that I can determine the quickest/easiest method of changing it into a digital signal.

Schmitt trigger is something I've investigated, they are cheap and plentiful, but I'd like to do without an amplifier stage before the schmitt trigger if I can get away with it.

Anyone here with electronics exp. care to chime in?

Dan

[mainlylinux]

Pickup coil replacement

I've also been hearing about the pickup coil wire issues. I'm thinking of ordering a pickup coil(s) from a 1985 Dodge B150 with the 3.7 litre engine.

You get 2 pickup coils in the same box for $15.00, and I think they could be modified to work in the xs11.

You have to put in your zipcode for the link to work.

49002 should work

Stator-coil

[LoserShoes]

Is the rotor a magnet? If so just use a Hall Effect Switch. Will need a mount fabricated, but lots less work then conditioning what you have.

If you want to use what you have, capacitivly couple it and use a resistor and zener diode to limit the input voltage. Look at some of the app notes on the National Semiconductor site. Or search on signal conditioning.

Steve

[mainlylinux]

Hall Effect

The rotor doesn't appear to be a magnet. I had thought about hall effect, to be sure. If I went to a hall effect sensor, I'm not sure how many guys would be willing to change over to it to use. I guess I could do a poll.

Thanks for the advice!

Dan

[randy]

No, the reluctor is not a magnet. The magnet(s) are part of the pickups. The reluctor 'bumps' the magnetic field as it passes.

Dan, I've done a bit of research and development on this, but I laid it aside last summer. I found that there are enough spare TCI's going around that can be had for less than $50. Not to say that the idea is a bad one, though. I know that one day the supply of TCI's will dry up. Then you can name your price!

FYI, the output transistor needs to be a diode-protected NPN Darlington, to be safe I'd go with 10 amp dissipation. Try NTE2317 or BU806.

And keep in mind that you have to power the coils all the time and turn the transistor OFF with the pickup signal.

I have a rough schematic of a Hall-triggered TCI at home, I can try to get it posted tonight if you'd like to try working with it?

[mainlylinux]

Yeah, if you can post the schematic that would be great!


Dan

[TopCatGr58]

Hey Dan,

As I mentioned in your Poll thread, the old Pickup coils and wires are a problem because the TIMING PLATE ROTATES for both centrifugal and vacuum advance curve processes!! The 81 removed the Centrifugal, which cut down on some of the flexing, and then in 82 the XJ totally immobilized the pickup plate and put both advance/retard curves into the TCI using a separate "black box sensor" to send the vacuum pulses info to the TCI!

SO....you could possibly use the old PU coils, and just state that the centrifugal and vacuum advance parts need to be immobilized with your new TCI, since it would have the advance curves built into the PIC! However, have you read the old magazine review article about the XS11? It talks about and explains about the vacuum "retard" unit and how it works to maintain the timing advance under the different load conditions so when cruising it's one value, and when under hard WOT, it's at another value, sorry, can't remember verbatem which situation is more or less advance, but they explain it very well!?
T.C.

[mainlylinux]

it's probably a MAP sensor, and that's what I'd propose to use, though probably one from a GM or Ford since those are easier to get than a yamaha one. The load is sensed by vacuum, i.e. under full throttle there is less vaccuum, at idle there is a lot of vaccum. Same thing many cars do.


I'm not sure why they say anything about retard, I just looked at mine and it can only move forward in one direction.

[TopCatGr58]

Hey Dan,

Here's a quote from the 78 Cycle Guide review article that describes the action of the vacuum advance/retard unit!

The Eleven ignition system's second important feature, and one that's unique to motorcycles, is the vacuum-actuated advance/retard mechanism. Actually, there hasn't been an automobile produced in at least 30 years without some form of inter-connection between manifold vacuum and ignition timing, simply because spark advance otherwise has to be compromised between the conflicting demands of power and economy. Engines running under slight throttle openings have a thin, low-pressure mixture in their cylinders, and they don't run efficiently unless the fire is started long before the piston reaches top dead center. Much less ignition advance gives optimum results at large throttle openings. Yet, all motorcycles but the Eleven effectively have a fixed spark advance, with a centrifugal device to retard the timing for easy starting. And their off-idle timing has to be compromised, with enough advance to give reasonably good efficiency under cruising conditions but not so much as to cause detonation when the rider uses full throttle. The Eleven we tested had 10 degrees of static ignition advance, and another 26 degrees from the centrifugal mechanism, which adds up to the 36 degrees other engines of similar configuration have needed for maximum power. But then there's also 16 degrees built into the vacuum-advance device, and that pulls the timing around to 52 degrees BTC when the bike is cruising along at freeway speeds. Wind the throttles open, and it drops back to the power-setting; roll off throttle, and it auto-advances for economy; use some in-between throttle position, and the ignition adjusts itself to suit conditions. It's a big step out of the technological Dark Ages, and one that's long, long overdue.

T.C.

[mainlylinux]

ttt

[Geezer]

Back when I was looking into this, early 280Z Nissan pickup coils were very similar. The looked very close until you put them side by side to see the mounting was a little different and the specs are otherwise the same.

I have a few extra sets so I'm not in need but I'm sure some auto pickups could be used if you want to fab up a new mounting plate and maybe a diffenent reluctor.

Geezer