Thorspark Electronic Ignition Conversion

[Alan @Ncl]

Thanks Olev and Marcus
That picture in the Pamco seems to indicate a fairly simple circuit with a Hall effect transistor driving a power amplifier of the type flagged up by Marcus.  Only two components seem to be presemt; a pull up transistor (I think that's what they call them) and a zener diode.  Looks like anyone with a bit of electronics nounce (probably not me ) could knock up something like this relatively easily? 

I suspect that this is probably what is inside a Thorspark, basically. Makes you wonder why, if it can be done as simply as this, do some of the electronic systems you see look so complicated (even ones that do not have electronic timing advance)?

Marcus, I guess you are saying that if I were to drive the low resistance coil with a current limiting device such as the one you have identified, it would work as designed?

I had another thought about Stu's recent post on this too.  I don't know much about CDI ignition but would like to know more.  Do you think that the 0.5 ohm Punto coil I mentioned is designed for a CDI system and what exactly is 'reluctance'? Is that the same, or similar to, Inductance?  I know they talk about 'reluctors' in the context of car distributors (replacing points) but never understood the term.

Alan

[MG]

yes, these devices switch the primary coil and act as current limiter to charge it (with short circuit protection, etc), so actually are doing most of the job. Some external components are required, and you might want some more features and a way of triggering the spark, but it is relatively easy to build a basic electronic ignition module around one of these.

Cheers, Markus

[chaterlea25]

Hi Alan, Markus and All,
For your info, heres a CDI circuit  thats for a Morini 3 1/2
The original morini transducer and coil was a one piece affair quite expensive to replace (2 needed)

I got this circuit on the net somewhere and built 2 of it onto a circuit board, I potted the board into  plastic electrical box 3 x 3in and used some yamaha CDI coils from a breakers, the whole lot cost less than £20 and it would throw a spark over an inch
The Morini is now long gone

Cheers
John O R

[Alan @Ncl]

Thanks for the circuit and the info, John and Marcus.  I actually bought a Maplin kit for £10 (which by my reckoning works as in the diagram attached).  I wonder if this does more or less the same thing? It does not seem to have any current limiting capacity though!  I am not completely sure about the implications of positive earth either, if its used with a CB on our bikes (npn vs pnp and all that stuff).

Alan

[chaterlea25]

Hi Alan
the Morini system is self generating, (coil inside the flywheel)
It generates a high voltage to charge the capacitor , I measured it at around  100 volts 

Cheers
John O R

[kiwipom]

hi guys/alan, just keeping in touch between quakes, alan did you ever get that bike going haven`t seen you on the forum for a while,cheers, bob

[Alan @Ncl]

Hello Bob
Thanks for asking.  Afraid I gave up a few weeks back and have not been back to it since. Just had a few nice warm days that I should have taken advantage of but have missed the boat now it seems.  Your prompt has awakened me again though so might have another go this weekend.

Out with some friends tomorrow who have just come back from hols in New Zealand.  They loved it.

Alan

[kiwipom]

hi alan/guys, thanks for the reply if your friend came down to Christchurch they would have seen the vast amount of damage, it will be years before it is fixed. We are waiting for our insurance payout so we can move on but they like to drag the chain, if i decide to come back to u.k. i will be bringing the A10 with me it was so close to finish but now is back in storage,cheers for now, Bob

[Alan @Ncl]

Sorry to hear you were so badly affected Bob. Did not realise you were right in the middle of it all and down in Christchurch. Must have been bloody awful. We sometimes winge a bit about the weather a bit up here at 55 degrees North but at least we don't have issues like that to contend with.  Glad the bike survived in tact, at least, but pity its back on hold.  Best wishes with the recovery strategy.

Alan

[lawnmowerman]

Hi Bob

Hope you sort things out soon. If you do decide to come back to the UK then get in touch - if you end up back in Canterbury then you will not be far from me.

Jim

[santi]

Haven't got one of my own but have seen them on 2 twins (not BSAs) I know well and they have done fine for several years.
 
Yup, electronic should be better - the downside in my opinion is that a 6v dynamo with 60W to play with is a bit marginal. I have one classic 'electronic' (Boyer Bransden) twin in the shed - and the ignition is certainly impressive. But that has a 180W alternator and electronic regulator/rectifier, so there's power to spare. I only feel confident without a mag with 12v and an alternator with modern regulation. And the biggest battery that'll fit in the space.
For 290 bucks you could pretty much get a mag restored. You could certainly get all the bits for that money for home-assembly.
Really depends what you're going to do with the machine in terms of daylight/night riding, on your own or in a group, etc - and how far from home if the dynamo or regulator goes awol and leaves you with that flattening battery syndrome. If I really wanted electronic sparks and had to stay with a dynamo, I'd convert to 12v, get a 12v version of the kit or a similar one, a DVR2 regulator . . .  and the biggest battery, etc.