dc/dc converter 12/200V

Wrong. My example is NOT inductive "storage"... it's CONVERT PER FIRING... the example shown can manage a firing every 2.25ms with the battery at 12VDC. AND: It HAS been run on many high RPM V8's, for YEARS... not a FIGMENT like lots of designs seen here on S.E.D ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

[snip]

Turning ON the transistor does two things... dumps the capacitor through the ignition coil primary (firing the plug) and begins charging L1.

When the L1 current reaches 5A a control circuit (not shown) turns off the transistor, which dumps the L1 energy into the capacitor.

Next point opening, or star wheel control signal, turns on the transistor, repeating the cycle.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

Hi,

I am building a cdi ignition for my motorbike.

There is enough available on the web but I can not find how to make a dc/dc converter that is small enough to place on a motorbike. What I have found has a large transformer.

I need a dc/dc 12/200V converter and the power is approximately 20 watt.

Knows anyone how to build this converter?

Tia

Jan

Even at 30Khz, there is no reason to need anything larger than a 20 to

30mm diameter ferrite pot core for 20 watts but with today's much faster switches, you should be able to go to a higher frequency and smaller core.

Ted

Your solution is not what i am searching for Here the pro for CDI ignition.

CDI stores the ignition energy in an electric field of a capacitor, Inductive ignition stores the energy in the magnetic field of an inductor (coil). The CDI can switch a large current through a low inductance/resistance pulse transformer very quickly so it is suitable for extreme spark rates. Inductive ignition needs time (dwell) to fill the coil with energy and time to discharge that energy hence the longer spark duration of the inductive system. A coil that is optimised for CDI system will not work properly with an Inductive System and vice-versa. Commercially available CDI systems can reliably push 150 amps at 450 volts or more through the primary windings of a CD pulse transformer but do so in tens of microseconds so it works much better at high revs.

Jan

"Jim Thompson" schreef in bericht news: snipped-for-privacy@4ax.com...

Hi Ted,

Thanks for your respond. Do you have a idea how many winding i need for the primery coil? Do i have to generate a perfect sinus for de primary if i use that high frequenty?

Jan

"Ted Edwards" schreef >> I am building a cdi ignition for my motorbike.

Hi Jim,

I have take a second look at the schematic but i don't see how it works. The only thing i can think of is that because the turning off Q1 if the current is 5A trough L1 there a induction counter to the current is being created. That energie goes in C1 until Q1 is turning on and is pulling that energie trough the ignition coil. If this is not the case, can you explain in short how it works? btw. Sorry for my bad english. I op you understand what i try to say.

Jan

"Jim Thompson" schreef in bericht news: snipped-for-privacy@4ax.com...

About the size of a SMALL filament transformer, but with a gap.

5mH @5A, rated to 140°C

When I was doing my research in this area I was having them made by Arizona Transformer Company, Arizona City, AZ, at a cost of about US$1 per each.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

I doubt the V8 can reach 12000 rpm like a motorcycle engine can.

--
Reply to nico@nctdevpuntnl (punt=.)
Bedrijven en winkels vindt U op www.adresboekje.nl

I think a lot of people reading this group (including myself) know how to build such a converter. However, I think you are looking for a diagram and a part list. I think the easiest way to get there is by building a step-up converter in the so called continuous mode.

You can look on the websites of TI and National Semiconductor for chips which can control these sort of circuits. Basically, you would need a controller chip, a high voltage mosfet, a fast high voltage diode and a standard inductor (one you buy, instead of winding your own) and some resistors and capacitors.

--
Reply to nico@nctdevpuntnl (punt=.)
Bedrijven en winkels vindt U op www.adresboekje.nl

dc/dc

ive built a few of these many years ago while I was at Uni for my suzuki gs550, some more reliable than others, I managed to get one down close to the size of a cigerette packet but this was too small and was unreliable as it got hot.

if you look at several of the ferrite manafacturers you find data sheets for their cores wich give tables for the size of the transformer you need versus operating frequency. you should be able to get quite small for 20w. especialy as you can go quite high frequency with a mosfet where as i was having to use discrete darlintgon setup.

i used the circular pot core for my designs, and an auto transformer style winding.

I used 2 gates of a cmos hex inverter IC as a simple relaxation oscilator to control the switching transistor wich sensed when the colector voltage of the transistor fell below 12v to switch it on, it also sensed when the capacitor voltage reached full voltage.

the other 4 gates to control the 2 firing signals for the thyristors - two coils for 4 cylinders as motorbikes dont have distributors like cars.

the charge per cycle design is interesting here but the size of inductor you would need to store 0.1 joules every cycle is rather large i would think.

Colin =^.^=

[snip]

Using what for a simulator?

5A thru 5mH is 62.5mJ ~ 350V on 1uF

As I mentioned in a prior post, 5mH (laminated iron core) with a gap, is about the size of a small filament transformer.

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

| 1962 | I love to cook with wine. Sometimes I even put it in the food.

I did put the schematic in a simulator. The speed is ok, the voltage over C1 is 100V. It can work. I wonder how bic a 5mH coil is with can take 4 ampere.

"Jim Thompson" schreef in bericht news: snipped-for-privacy@4ax.com...

That is very elegant. But is there an advantage to having an energy-storage inductor, an energy-storage capacitor, and a coil, when all three can be combined into one part, namely the coil?

John

As Frithiof say, "CHEAP".

Power dissipation is much lower... device is always saturated.

Simple control requirements allow use of star-wheel-magnetic pickup OR points.

Inductive storage requires either a shaped pickup or complex control system for low dissipation and avoidance of coil current all over the map. Remember, charging an inductor takes a fixed TIME, NOT a fixed number of degrees.

Timing advance is there to fake out a constant TIME before firing... flame front movement.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

At last! Someone understands!

Actually not my original concept. It was an idea by a Philco-Ford (Sunnyvale) design manager that I replaced in 1968, (first name I can't recall) Josephson (not of "junction" fame :-).

But he couldn't figure out how to control it. I did.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

Only if you time the base drive right. Your circuit really needs "on" timing adjustment as a function of battery voltage, or alternately a current sensor.

That's easy. Your circuit needs base timing, too. 50 cents worth of uP looks like a pretty good deal to eliminate a big inductor and a big cap.

I'm so grateful I have revered elders around to teach me the fundamentals.

John

Don't be a smart-ass, John. Modern inductive storage ignitions DO just that... BUT... it requires a pickup on the flywheel so you know where you are.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

Why? It's a simple timing thing to turn on the coil drive some reasonable number of milliseconds before the "points" give you the firing signal. After all, just the firing signals tell you the rpm's, and everything follows from that. Might as well do the advance in software while you're at it. Going constant-current certainly helps during cranking and such, but that's a refinement.

John