Saving Old Seagulls

I've been watching this with interest, but am totally baffled House wiring is about my limit when it comes to electrics. I suspect I'm not the only one

Can you explain to a simple boy like myself the reasons, benefits and what this replaces? Also how does it work? If there are no points, what sends the signal to spark?

Question;

It appears that there are only 3 electrical connections to BD 649 B,C,and E which appear as pins on the transistor.

If we want an efficient heat sink, why are we isolating/insulating the transistor heat sink from the larger heat sink?

Is one of those pins [emitter] connected to the heat sink internally?

Hi Oyster, Reason to replace points? No reason unless you are having trouble with the orig points. Or if you have a motor that points are not avalable any more, in my case an aircooled 5hp Tohatsu & a Tas outboard. Or points are a rediculouse price. How it works? Very simply put as the magnets pass the Ign coil there is a voltage buildup to about 10V, at that point the transistors are trigered giving a collapse of current through the Ign coil primary(same as points do) this creates the high voltage in the secondary winding, giving spark at the plug. If you want the full details on the original module & its description its at US Patents No 4,163,437 Aug 7, 1979. They dont give component values thats the part i had to work out. Will try & post ocilliscope picture of the unit working.

Hi Phil The collector of the transistor is conected to the mounting tab, this needs to be isolated from the heatsink. The reason its isolated is if you are using it on a Wipac coil the collector side goes to the coil conection where the points were before removal. If it wasnt isolated it would short out & not work. The Villiers coil the polarity of the module is reversed. I also suspect some reliabillity issues with the original module may be poor heat sinking as i found if they werent mounted on a heat sink the switching transistor got quite warm. Excessive heat in any electronics is not good for longterm reliability.

They had some other colored modules as well meant for 2 cylinder with colors to indicate use, and I think possibly 1, for 2 cylinder and variable timing as on 50s OMC and Merc motors?
Have you had any of these other modules apart yet?

Hi Phil I do have a purple Mod7 fixed ign for OBs. Brown Mod209 Chainsaws with points. Blue Mod207 for mowers. Red Mod215 OBs with throtle adjust timing, this is the one I dismantled & at $30 each wont be dismantling any more. Motors with 2 coils require 1 module per set of points.

Manifold had a great sugestion of using U aluminum for the heatsink as its easier to pour resin in to. So built another one & used a countersunk screw to hold the transistor.

This is the best i could do in geting pics of a Villiers coil wave form. First pic is points & sec pic is the IGN module.

Can you read the voltage on your scope?
What are the revs?
What's the voltage of the cap that your replacing?

Speed was about 2000RPM Voltage on wave form with module about 60V. Most IGN capacitors ive come across are 250V rating.

For those that are woried about reliability you could use a BD651 transistor for Q1. It has a higherVce of 120V, this should well cover it. Only costs about 60c extra.

Could this be put together as a kit and sold via SOS, with simple set of instructions?

Obviously a long term test should be done first over a month or two?

Is there any one in the UK thats runing a Seagull fairly regularly & long periods with either Villiers or Wipac points systems ? If so are they prepared to try a free IGN module for reliability ? PM me with a postal adress & i will airmail one with instructions.

Fitting the module under flywheel on a Wipac model. Points wiring need to be disconected.

Earlier in this post Ive put the Module as reverse conected for Villiers coil, NOT so Same as Wipac Brown to points conection on coil & Blue to Ground.