Author Topic: Transistorized ignition, points style. First ones are ready!  (Read 23491 times)

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Offline HondaMan

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Transistorized ignition, points style. First ones are ready!
« on: November 22, 2006, 11:03:09 PM »
I've discovered that, 20 years later, I can build the same "points triggered" electronic units I did in the 1970s with just 3 parts and a heat sink (lots less parts!). I'm going to make a buy of the parts: is anyone else interested in a set? It will be for SOHC-4 engines only, running Honda coils or, if I can test my Dyna 3 ohm coils, with those, too. I figure it will be between $20-$35 for a set of parts to run one bike. The transistors are no longer manufactured, but there are thousands of them out there in inventories around the world, I just found them on Google.

The general idea here is: it runs on the points, but takes most of the current away from them so they last a long time. My old ones were good past 10,000 RPM, so I imagine these will be, too. If it fails on the road, you just swap the coil wire(s) back to the points and ride on, so it has a built-in backup mode. The spark voltage is like the Dyna "S" units, about the same as stock.

I still have the holes under my taillight where someone stole mine while I slept in a motel one night long ago. I think I'll make it fit those holes, just 'cuz...  ::)

1/1/07 update: the tests are going well! The enclosure will be about 4" x 2" x .85" for the Fours. This will fit perfectly under the battery box on the CB750, so I'll work up a mount plate for this method, which can be held down by the battery's case, for those who want it that way. It's a good spot, out of sight, so maybe it won't get stolen this time!
« Last Edit: April 28, 2007, 08:12:08 PM by HondaMan »
The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

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Offline Terry in Australia

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Re: Transistorized ignition, points style. Interested?
« Reply #1 on: November 23, 2006, 01:47:23 AM »
I'm in mate, I love gadgets! ;D
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Offline Jay B

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Re: Transistorized ignition, points style. Interested?
« Reply #2 on: November 23, 2006, 09:40:11 AM »
I'm in too.
Jay
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Offline ic455

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Re: Transistorized ignition, points style. Interested?
« Reply #3 on: November 23, 2006, 08:09:33 PM »
Are there any other benefits besides increased points life?



Offline medic09

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Re: Transistorized ignition, points style. Interested?
« Reply #4 on: November 23, 2006, 08:10:48 PM »
Are there any other benefits besides increased points life?

ditto

Does one still adjust the timing the same way?
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Offline HondaMan

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Re: Transistorized ignition, points style. Interested?
« Reply #5 on: November 23, 2006, 09:14:28 PM »
The main advantage of this system is: longer points life, even if you use higher-current coils like the Dyna II "green" coils. If your engine's in good shape, you can close down the points gap a little (.012" instead of .014"-.016") to get some more dwell and longer rubbing block life, helping you to reach more RPM (hotter spark). In fact, it will be the rubbing block that will wear out, not the contact faces.

Points and timing are still set the same way. If the unit fails for some reason (or gets stolen...), then you can plug the points back into the coils (usually the blue & yellow wires behind the oil tank, CB750), and ride on. I ran them with the .012" gap: when I had to change back I just opened the gap to .014" again and turned the whole points plate a little clockwise to re-establish the proper timing and dwell. Technically speaking, the .012" gap would work OK, but the contacts will wear a little more quickly because the gap is set at minimum.

I'll buy about 10 transistors and 5 sets of other stuff: then I'll build one up to test and re-post with the results.

Remember Heathkit? Maybe I should offer that....   ::)
The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: http://forums.sohc4.net/index.php?topic=65293.0

Link to website: www.SOHC4shop.com



Offline bill440cars

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Re: Transistorized ignition, points style. Interested?
« Reply #6 on: November 23, 2006, 10:53:14 PM »


           Mark, Got a PM coming at ya. ;D


                                                      Later on, Bill
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steveko

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Re: Transistorized ignition, points style. Interested?
« Reply #7 on: November 24, 2006, 02:27:04 AM »
I'm also Interested



Offline 750goes

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Re: Transistorized ignition, points style. Interested?
« Reply #8 on: November 24, 2006, 03:05:33 AM »
I'm in if there are some left..............anything to make better spark..... does it come with a really basic wiring diagram as well ??

thanks Hondaman....



Offline oldfordguy

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Re: Transistorized ignition, points style. Interested?
« Reply #9 on: November 24, 2006, 07:53:48 AM »
HondaMan:

This would work for a CB450 Twin as well, wouldn't it?  I would be interested in plans or a kit.

Matt



Offline dusterdude

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Re: Transistorized ignition, points style. Interested?
« Reply #10 on: November 24, 2006, 08:18:31 AM »
count me in
mark
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Offline HondaMan

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Re: Transistorized ignition, points style. Interested?
« Reply #11 on: November 24, 2006, 04:09:00 PM »
Wow.   :o

I ordered enough "stuff" last nite to make 10 units, maybe should order some more (?).
It won't arrive until mid-December, says the post, because they are coming from Motorola Singapore, so they must pass customs. At this season, that will take a few days. Add in Christmas (family, ya know...) and intermittent warm-enough-to-test-outside January weather, and it may be late January before I have packaged versions.

For those of you who are circuit-board "sparkies", I might be able to rustle up a kit form. The circuit is similar to the one Ford used on the SOHC 427 engines (8500 RPM capable), but simplified to remove the RPM limits, sort of like the one GM had in the Corvette (and, I think, the Z-28 Camaro?).

I am sizing the electronics to run 8-amp coils so there's plenty of "headroom". This will mean that any two-coil setup will work. The bugger has always been the 2-output coils on 4-cylinders, because they tend to have a prolonged "kickback" at the transistor, due to imperfect matched windings on the 2 outputs. So, any engine with 2 smaller (1-output) coils will work OK with them, too.

The weather has been colder than normal here, which has hampered the Swingarm service thing (the garage has limited heat, and metals don't like to be turned cold: it makes them hard to measure to a final dimension). So, maybe I'll make these until it warms up a little more.

I've personally always liked this style better than the Dyna, because it is harder to change out the Dyna if it dies on the side of the road somewhere. This one just requires swapping those little bullet connectors and you're on your way again, with stock sparks. With it, you usually get better MPG and smoother performance. If you're into lots of RPM, it helps there, too, by keeping the coil current "like new points" forever. With the high-flying cost of the points these days, it seems like a good time to bring this out again.

The main difference between this arrangement and, say, a Dyna III, is this: the Dyna units increase dwell a few degrees, which is how they boost the spark voltage a little on stock coils: the voltage doesn't "droop" so much above 2500 RPM. This transistorized version, with stock ignition settings, won't improve the "droop", but will keep the coils always running at full current, like a fresh tuneup. If you decrease the points gap a little, this will increase dwell a little (about 3 degrees or so) while also reducing rubbing block wear and increasing the upper RPM limit before points bounce sets in. And, it's cheap!

I'll keep ya'll posted (my wife's from Texas, gotta practice for the relatives for the upcoming holidays...).   ;)
The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: http://forums.sohc4.net/index.php?topic=65293.0

Link to website: www.SOHC4shop.com



Offline Terry in Australia

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Re: Transistorized ignition, points style. Interested?
« Reply #12 on: November 24, 2006, 05:26:44 PM »
Woohoo! Looks good HM, I remember seeing a similar system on Ebay awhile ago, but they must have all gone, sadly. To negate the effects of points bounce, you could just "double spring" them, like we did in the old days? Cheers, Terry. (#1 customer!)  ;D
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Offline Patrick

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Re: Transistorized ignition, points style. Interested?
« Reply #13 on: November 24, 2006, 09:00:09 PM »
I also would be interested.....

Patrick
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Offline Raul CB750K1

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Re: Transistorized ignition, points style. Interested?
« Reply #14 on: November 25, 2006, 06:31:57 AM »
I guess what you are doing is using the breakers to polarize a transistor, that will drive the coil current instead of the breaker itself. Will you retain the capacitor to avoid the coil destroying the transistor, or will you use a reverse diode? What about the transistor, is it really such a big deal and only a discontinued model will do? Can't you use any modern device? Is it a simple transistor, or is it an IGBT, MOSFET, Darlington, whatever? Are there more circuitry added or a simple semiconductor? And finally, have you checked the response time of the transistor? At high RPM it can mean some degrees of crankshaft rotation in delay...


Raul



Offline Terry in Australia

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Re: Transistorized ignition, points style. Interested?
« Reply #15 on: November 25, 2006, 06:38:40 AM »
Geez Raul, you must have ESP mate, I was just gonna ask HM all those questions too, what a co-incidence!  ;D
There are two kinds of people in this world, Motorcyclists, and everyone else............

Scooters are for guys who want to ride motorcycles, but still want to feel the wind in their vaginas.........



Offline 8 Track

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Re: Transistorized ignition, points style. Interested?
« Reply #16 on: November 25, 2006, 06:43:16 AM »
Geez Raul, you must have ESP mate, I was just gonna ask HM all those questions too, what a co-incidence!  ;D


???????????Really??????????? ???



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Offline Terry in Australia

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Re: Transistorized ignition, points style. Interested?
« Reply #17 on: November 25, 2006, 06:51:21 AM »
Ok Strokey, you got me there, I've no idea what he meant................  :-[
There are two kinds of people in this world, Motorcyclists, and everyone else............

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Offline Raul CB750K1

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Re: Transistorized ignition, points style. Interested?
« Reply #18 on: November 25, 2006, 07:24:37 AM »
I'm curious because I've been thinking in the subject for a while, but being quite busy and not being in a hurry I've been delaying it. If Hondaman has already designed the circuit it's not really worth it to break another trail just to arrive to the same destination...


Raul



Offline HondaMan

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Re: Transistorized ignition, points style. Interested?
« Reply #19 on: November 28, 2006, 10:05:33 PM »
I guess what you are doing is using the breakers to polarize a transistor, that will drive the coil current instead of the breaker itself. Will you retain the capacitor to avoid the coil destroying the transistor, or will you use a reverse diode? What about the transistor, is it really such a big deal and only a discontinued model will do? Can't you use any modern device? Is it a simple transistor, or is it an IGBT, MOSFET, Darlington, whatever? Are there more circuitry added or a simple semiconductor? And finally, have you checked the response time of the transistor? At high RPM it can mean some degrees of crankshaft rotation in delay...


Raul

The particular Motorola transistor I'm using is specifically built for this job. It has a Vceo of over 400 volts with a corresponding Vcbo (very rare) and high gain, plus a built-in, characterized, snubber diode that will allow supplementation with another as well. It is a bipolar type, so static sensitivity and gate charge/discharge is not an issue. The response time is measured in a few nanoseconds, no delays there (heck, 10,000 RPM is only 167 hz, or 5,988,023 nanoseconds per cycle, which isn't even a good warmup for a switching transistor!). The condensors can be left in place, but they cause a short timing delay (about 1 degree or so), so I ran with them disconnected before (I reconnected them after the unit was stolen off my bike and I was forced to swap back in mid-trip).

Many "modern" transistors are of the types you mention. IGBTs and MOSFETs suffer a fragility in this type of system: once their gate is charged ON, they must be forcibly charged OFF to turn off the collector current, or else it will remain on. This requires some extra circuitry that must be compensated, in the case of a vehicle used outside, for temperatures of -30 to +240 degrees F, which becomes some expense. Capacitors that could be used to generate such a charge pump circuit would have to be solid tantalum types in axial packages: the typical temperature coefficient of a 4.7uF, 35wVDC epoxy-cased type would cause timing drift of the turn-off pulse of +2.5 degrees at +200 degrees F if the timing were set at 70 degrees to start. Such things then require all sorts of compensation trickery, and a CDI would cost about the same when it was all done.

That's not what I wanted.  ;)
I just don't want to keep paying $40+ for points, then have to imitate a frog for an hour while I install and set them.   :P

The extra circuitry is "bomb proofing" stuff. Mostly, handing a device that was very simply designed to someone who doesn't fully understand it results in destruction from improper installation mistakes. Also, there is the occasional bike with bad grounding, which greatly increases the back-EMF attacks on the switcher, and the user who has a high-current coil (or shorted coil or wiring), stuck voltage regulator, or dried-out battery, any of which can easily result in 6+ amps per coil in the CB750 systems. All of these things must be considered or the gadget will have a bad reputation in the end.

I don't want to do that, so I'm picky about my parts.  ;)

The main transistor is NPN: to invert the points without winding special toroid coils (the 3-part version) will require an inverting preamp transistor between the points and the coil driver. A type 2N3733 might do this: something easier to package against vibration would make me feel better, though, so I'm still looking at those candidates. I don't want to have to pot this thing, because any repairs would be too hard to do. Proper design of the packaging will preclude this: in today's marketplace, potting is used to cover a multitude of manufacturing errors that occur, while also hiding the "secret" circuit. I don't really care if someone else "steals" the circuit, as it has been done 100 times already.

Besides, it's been stolen before, from me!
The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: http://forums.sohc4.net/index.php?topic=65293.0

Link to website: www.SOHC4shop.com



Offline 750goes

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Re: Transistorized ignition, points style. Interested?
« Reply #20 on: November 28, 2006, 10:43:46 PM »
Hey HondaMan,

Does that previous post mean any dumbass can install it, I know positive and negative, will that get me capable of installing one of these doo hickeys??

Hey Raul - does that answer your question ??

So far above my head that post is in the clouds.........no complaints, just mind boggled......

I still want one, will the items be available as per the resposnes received on a first come first served basis ??

thanks  :)



Offline jaknight

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Re: Transistorized ignition, points style. Interested?
« Reply #21 on: November 28, 2006, 10:56:08 PM »
Hey there HondaMan,

     Sounds very interesting, but I have lost track on the number of applicants.  If there is enough to go around, I am interested also.

     If I don't make the first "draft", perhaps a second line could be called to play from the bench?

     ~ ~ ~ jaknight ~ ~ ~
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Offline jabbadeznuts

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Re: Transistorized ignition, points style. Interested?
« Reply #22 on: November 28, 2006, 10:56:52 PM »
Granted it would kinda cramp your goal of selling the kits, but is it possible to just get a parts list?
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ktp1598

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Re: Transistorized ignition, points style. Interested?
« Reply #23 on: November 28, 2006, 11:25:31 PM »
Sounds like a great idea! I am circuit board savvy and can make my own if I need to, or put a kit together if you sell one. Count me in. 8)



Offline Dennis

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Re: Transistorized ignition, points style. Interested?
« Reply #24 on: November 28, 2006, 11:53:23 PM »
I've also been thinking and occasionally talking about this for probably about 4 or 5 years now but never did anything about it. Originally I wanted to do it for my (dare I say it? - Yamaha) RD350, renowned for it's notoriously weak ignition. I'd be interested in several sets. The RD of course, the CB750F and at least one of the CB500's.
Thanks
« Last Edit: November 29, 2006, 12:20:43 AM by Dennis »