Dyna electronic ignition? Good Idea or no?

Most likely Darlington pair BJT configured for high voltage (rather than high gain as some/most Darlington pairs are). Dyna S has the Hall sensor, amplifier, and output driver all in one encapsulated enclosure attached to the timing plate. The Dyna III had a remote box containing most of the electronics, with a Hall sensor on the timing plate..

loudhvx wrote: If the Dyna S does in fact blow up from low voltage... one way to fail, that comes to mind, could be too little gain in the output stage, allowing the driver to go into the active region, thus creating a lot more heat in the driver (transistor).

But if it is any kind of decent design, it would be using pulse drive to the power device, not constant drive so that the power device could only be on for a fixed time interval. It would not go on again until receiving another signal pulse from the hall effect sensors.

I have a CDI that I built way back around 1980 (works with stock points) and it uses pulse drive to the SCR gate so it can never stay on steady.

I am just surprised that Dyna hasn't figured out how to protect their units better. I always assumed if they were croaking it was probably caused by some kind of voltage pulse picked up by the hall effect sensors and conducted into the unit where it's going into sensitive circuitry.

loudhvx wrote: Most likely Darlington pair BJT configured for high voltage (rather than high gain as some/most Darlington pairs are).

I can remember a big selection of ultra fast switching Darlingtons with voltage ratings of 600V or more and current ratings of over 10A. Those types of parts were the main switch element of all switching converters throughout the 80's before MOSFETs became economically feasible. Maybe they are cheaping out on the parts or just using crappy suppliers.

bountyhunter wrote:

loudhvx wrote: If the Dyna S does in fact blow up from low voltage... one way to fail, that comes to mind, could be too little gain in the output stage, allowing the driver to go into the active region, thus creating a lot more heat in the driver (transistor).

But if it is any kind of decent design ...

Nuff said.

It is purely a crude, DC coupled drive circuit. When the Hall sensor is active, the coil circuit is on. No current limit. No time limit. Meltdown is always possible. It is up to the user to protect the circuit by turning the bike off... no better than points with respect to safety.

However, that said, Dyna has been a very good company to it's customers and has been very good about replacing burnt units.

That's good to know.
Steve

loudhvx wrote:

bountyhunter wrote:

loudhvx wrote: If the Dyna S does in fact blow up from low voltage... one way to fail, that comes to mind, could be too little gain in the output stage, allowing the driver to go into the active region, thus creating a lot more heat in the driver (transistor).

But if it is any kind of decent design ...

Nuff said.

It is purely a crude, DC coupled drive circuit. When the Hall sensor is active, the coil circuit is on. No current limit. No time limit. Meltdown is always possible. It is up to the user to protect the circuit by turning the bike off... no better than points with respect to safety.

However, that said, Dyna has been a very good company to it's customers and has been very good about replacing burnt units.

OK, strikes me odd they wouldn't improve the product. I worked at a company that made power supplies for ten years and the thing that pissed the company owner off worse than anything was when one blew up and came back. I was fanatical at trying to overdesign things and my boss was the opposite so we sort of canceled out. His name was John Farnsworth Brown and his initials were "JFB". We used to laugh and say that "JFB" stood for Just F---ing Barely....... which was his design philosophy :laugh:

Well, the Dyna S is already in a very small package. That's two complete ignition circuits in the space of a pair of points. Maybe there just isn't room for anymore components without going to a total redesign using a uC. That probably wouldn't be cheap.

It's not like everyone that installed a Dyna S had failure. It's a good system, and best thing is it's simple. No black box, no extra crap to go bad. I like the system and have used it extensively and it's not fragile and going to go bad very often if ever for most. It does take more power to run as Lou has said. I checked that out, but otherwise a good reliable alternative to those that don't want to fool with points every 500 miles. Not trying to be excessively nagging on points either. All the KZs I had with points, I was doing good to go 500 miles without some point related crap of some kind or other.

I like the CDI design because it uses stock points which are indestructible, but there is almost no current through them so they don't wear or degrade. It also operates on pulse only so it's impossible to ever get DC current through the coil, just a short pulse. The only time mine ever blew was when I had an electrical system failure that sent the system voltage up above 18V. Took out my CDI, headlight, brake light, instrument lights, turn signals.

A lot of guys won't spend the money but the C5 is definitely a superior option to both point and the Dyna S. No mechanical advance required, tri-fire spark so less scavenging of raw fuel. The coils don't turn on until the crank turns. Consumes less power than the Dyna.