pancake generator

[dave bushell]

The regulator cuts in at 6.3 – 6.7 volts. It regulates output at 7.8 – 8.2 volts at around 20*c with slight variations above and below this temperature. It will cut out when dynamo output falls below approx. 5.0 volts. The 0.7 ohm resister that I quoted represents the series coil in the cut-out part of the regulator and which carries the full output of the dynamo and has to be of similar low resistance.
Therefore, using the regulated voltage of 7.8 – 8.2 volts and an output current of 10 amps, we get a dynamo output of approx. 80 watts.
Dave

[Deleted User]

Dave I have sent you a pm. By the way whats it like in Caterham these days, I spent the worst three months of my life there in the winter of 1955 when I joined the Grenadier Guards. cheers Eric

[Deleted User]

A few years back I was allowed access to David Holder’s cache of Scott spares and have photos. He had half a skip full of the housings for the slim alternator as fitted to the Birmingham Scott.
Unfortunately for him, I think that the time taken to sort out individual spares, clean them up a bit means that to be economic, the price would be unacceptable. As his business is in manufacturing new spares, the same time is much more profitably applied to his day job. Many years ago, the then spares secretary Brian Lilley, used to drive down to David’s stores and rummage around all day to sort out spares either already requested or that were frequently requested. The pile was estimated by David and the cash paid over. In this case David’s time was minimal for a reasonable sale. The usual answer now is that “David thinks that they do not have any” This is diplomatic speak for “Its not worth my time”
Unless some rich saint comes along and makes a bid for the lot, nothing will change.
A little hard perhaps, but David is not running a charity and we should understand that. Roger

[Deleted User]

andy rowett wrote:

Hello Eric,
I am just attempting to run an AC generator inside the MC45, it means gutting the original and fitting a small AC generator and reg/rec, if it works, it should give excellent electrics, and still look original. Whatch this space.

I had a similar idea. Ferret’s Electrickery provided a small diameter alternator stator/rotor set (made by Electrex) to go inside the MC45 housing. The axial length of these components is about 1/3 of the old DC armature which will make it possible to construct a much more “pancake-like” instrument. No, it won’t look original but with the old end fittings and a splash of red paint on the housing there will be a family resemblance! The clackety-clack problem must be solved one way or another, but it will then provide 120 watts. A much lighter and less bulky solution with an extra small benefit – it will no longer irritatingly foul the toe of my left boot.

The debate about MC45 output. I converted to 12V with an electronic regulator – mainly to drive a Boyer ignition – but it does need more revs to cut-in and struggles to give a decent charge rate. Watch this space as well.

[Deleted User]

As you are obviously interested in generators, I will repeat something I did some time ago. I let in an aluminium plate to the RH side of the flywheel and fitted about 16 high energy pot magnets and fitted a mounting plate inside the RH case cheek on which to mount coils. There is also a ring of holes to fit trigger magnets for the ignition. The idea was to generate power and sparks without fitting anything to doors on a new engine for my Silk Scott. The plan had not progressed due to other work and the need to get special coils specified and wound. However I then decided to turn the bike into a classic racer so I will not need lights and as I already have coils as per Tony Harris’s BTH magneto, then I can just fix it up as an ignition. If you want pics just email me. Just something to think about. Roger

[Deleted User]

The idea of a flywheel generator makes much more engineering sense than crankcase door contraptions. No problems with clatter for a start. However, it does seem a technical step too far, at least for this amateur mechanic, at this time. Perhaps when the idea has been developed further, and demonstrated, it could be part of a later project.

[BRIAN MARSHALL]

With such a very big, large diameter flywheel as the Scott has, you could pack a heck of a lot of powerful button magnets around the outer flange, and put them on both sides too. With the right shaped coils, placed hidden away between the crankcase cheeks, you ought to be able to power up the Blackpool Illuminations…..
I suppose that you would have to mount a flywheel on a tapered mandrel in the lathe, and then experiment with different sizes and shapes of windings, and also decide just where to put them in relation to the magnets whizzing round.
Brian

[Deleted User]

Exactly so Brian, As I said, most of it is done and I can use it as an ignition system now, but I am not an electrical engineer and so am not able to specify the coils to use for providing lighting. As you observe, given the diameter and thus passing speed and the number of magnets, then it should give much more than enough power. I sent an inquiry to Bath university who have courses on electrical engineering to ask if they could help. Perhaps a student could use this as a project. The actual work of fitting an aluminium disc with holes to accept an even number of high strength pot magnets arranged alternatively N & S is not great and it is all quite neatly hidden away. Perhaps I should put a bit in Yowl to see if we have an electrical engineer with such experience in our ranks. I had intended to fit the flywheel in the lathe and coils on the toolpost and measure output. I more fear it producing too much output and burning things out, but then these aspects are the province of the electrical systems designer, hence why the project is on hold. We all need help sometimes. Roger

[Deleted User]

Electrical engineer ? Me neither! Which is why I tend to back away from suchlike projects.
A thought does occur though, about the flywheel endfloat. Does it mean that the air gap between magnets and coil cores would have to be greater than ideal? Perhaps it would be of no real consequence given the great power potential of such a diameter.

[BRIAN MARSHALL]

There was a local chap, sadly now deceased, who would have loved to advise us ! He was a retired electrical engineer, and spent all his time inventing gadgets and experimenting. He had a Ford Escort that was powered by an American torpedo motor ! He would assume that most visitors to his house would know little or nothing on his pet subject, and when he showed me under the bonnet of his car, I surprised him by asking if the windings could be switched between being connected in parallel and in series, the system used in electric trains to obtain good performance from a standstill, switching over for higher cruising speed. I also asked him about battery life, and whether or not he prolonged their life by adding EDTA tablets to the cells, (Ethylene diamine tetra-acetic acid, from memory). I instantly became a good friend instead of just another acquaintance ! I was doing my motor vehicle engineering course at the time, and so these things were all fresh in my mind, together with stuff like the sulphation that caused lead-acid batteries to fail. Sadly I don’t know anybody else with the knowledge that we need, but hopefully there will be a member who can advise us… ?
Brian

[Deleted User]

I will write a note for Eddie to put in a future Yowl. Thanks for your interest Brian Roger

[Deleted User]

Hello all . May I first say that the only lighting that I have had on a Scott was calcium carbide powered , so I have no knowledge of electrikery Scott fashion . The following I would say has most probably been tried before ( so get the AAkit ready ).Would it be possible to take a V belt drive from the clutch drum to a small alternator perhaps under the saddle , there are some very small alternators fitted on mini garden tractors I would not know their output . this I know would not do for those that want to keep their bikes to original spec . But I bet it would run without the clatter of the crank driven lot. Regards D F .

[BRIAN MARSHALL]

The problem with that idea I think, is the large diameter of the clutch drum, which would spin the alternator about twice as fast as needed. The small garden tractor alternators, such as the excellent Kubota, are intended for use on relatively very slow revving diesel engines, with windings to suit. I know that the late Don Hewitt fitted one to his Scott special, and Barry Jackson now owns the bike. Might be worth talking to him about it. I do know that Don rewound the alternator for use on the Scott, so there is a lot of work involved.
Brian

[Clawed]

Brian that is incorrect. It is a 6 volt battery, when fully charged each cell has 2.2 volts.
To charge it need about 7 volts. They are a 7 volt system.
If you do not believe me check the running voltage on a 12 volt system. It will be about 14 volts.

Clawed

[Clawed]

Should have followed this to the end, sorry.

Clawed

[Author]

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