cu. in.

Matt,

You are describing a turns ratio of 450/15 or 30:1. I am far from an expert in this field (pun), but I thought that 80:1 was more commonly used.

Bruce

Matthewt

hi,Bruce

I know very little abou all this. I trying to find out all I can on this. When I get time I will try to scan the paperwork I have on all this,and poist it.(I dont own a scaner yet, I have to use my cousin's.)Another thing is the instructions does not tell the length of wire needed on the primary, or the feedback just the secondary.So with out knowing the size of the toroid core itself its a guess.And does any one know if all toroids contain the same material?(Ferrite)Just wondering before I spend the time trying to wrap the core I found in my old computer. I unwraped the wire from it already it is yellow.I found it in the box where the power cable inters the (CPU).

cu. in.

Matt,

I thought you were talking about the high voltage coil that fires the plug. This is the coil that takes say 200-300V on the primary and converts it to 20,000V+ on the secondary to fire the plug. If you are talking about something else, then ignore what I said in post # 300.

Bruce

ZAGNUT

My Feedback: (1)

there are a bunch of different toroids to choose from but so far i've only tried the plain black ones and had good success. winding a 1/2" OD toroid can be a real pain so next time i'll try E cores

don't worry about wire length for the primary and feedback coils, number of turns is what's important and since there are so few all you need is a short piece of wire. the wire for the secondary has to be first wound around a "shuttle" to make winding easy so they give a good starting point for wire length...


dave

Antique

My Feedback: (4)

Dave, What does an "E Core" look like ? An "E", not a donut ? A picture of one would be a good thing.

ZAGNUT

My Feedback: (1)

actually a pair of "E" cores is needed...coils are wound on a plastic bobbin (very easy!) and then the core halfs are assembled around it and glued to each other

no doubt you've seen this kind of transformer core a million times but most likely of the laminated sheet steel type. for our high frequency use we need ferrite cores


dave

Antique

My Feedback: (4)

Dave, Thanks for the picture and explaination. I take it that after the primary is wound around the bobbin, the center legs of the e-core are slipped into the bobbin from each side and glued together. If that part is true, where on the e-core do the secondary and feedback coils go ? Thanks for the education.

c_moore

They go on the Bobbin.Not Shown.These are what I use and they work Great.I Take the Bobbin and drill a hole at each corner(4) for the wire to come through. I start out with the secondary.Ithread the Start side through a Predrilled hole.Lop the end through twice to keep the wire in place.I hae made a turn counter and I count the turns.When Finished I cut the wire off the spool and loop it through the adjacent hole.Then I turn the bobbin around and do the Primary.Then the Feed back.Pay attention the the start side of the feed back and the Primary.All the turns thave to go in the same direction.When finished I add the E cores and use varnish the hold everything together.The whole process takes Me about 30 min.

ZAGNUT

My Feedback: (1)

that's quick! a toroid takes forever and the only way to count turns is with pen and paper or one of those pushbutton thingies they use at club or theater entrances...

will this type of transformer work good with the simple oscillator circuit the RCM ignition uses? or does it need something more complicated like the 3W ignition that has a pair of transistors and a bunch of other crap?

any way to calculate the frequency according to the component values used?


dave

c_moore

Hi Zagnut,


Yes! It works great.Better than a Torroid in my opinion.I added to the RCM version and what I ended up with is Better.The transformer has 250turns on the sec,8 turns on the FeedBack,and 16 Turns on the Primary.The output of the SEC one leg goes to ground and the other goes through a Voltage doubler.I get 400 volts.Idon't know how to calculate the Freq.But I play with the values of the Resistors until I get the Right voltage.

ZAGNUT

My Feedback: (1)

thanks! this will make my next ignition much easier and maybe even lighter


but why the voltage doubler? i'm getting about 180 volts now and that works just fine with a tiny 3W coil (100:1 ratio) plus keeps the main cap size fairly small.


dave

Antique

My Feedback: (4)

Pictures boys, pictures ! Some of us have a hard time visualising it !

c_moore

Zagnut,

where do you get your coils?I use the Voltage doubler because I use CH ingnition coils.I need around 400 volts.I will try to post pics as soon as I can.

Matthewt

hi,what is the size of the wire used for secondary, primary,and feedback?and what are the dimensions of the bobbin and e-core?

Matthewt

hi,Thanks for the help.Does the e-core have to be 1/2'' od? or will any size work?Also my plan says to soider a short peace of flexible wire to each end of the secondary?WHY??? The plan does not give the reason..

ZAGNUT

My Feedback: (1)

the coils i dug out of old 3W ignitions and also hand wound a couple of copies. these are about 12mm diameter x 14mm long and weigh nothing. the primary is wound directly on the ferrite rod core and stuffed into the secondary's bobbin which is a six layer stack. no insulation between the secondary windings. basically a standard trigger coil with 100:1 ratio

the main cap in the 3W is rated at 250 volts so i doubt their converter is putting out more than 200. have you tried the CH coil on less voltage?

dave

ZAGNUT

My Feedback: (1)

probably because the secondary wire is very thin and fragile. if these heavier gage extensions are secured to the toroid with some thin tape you won't end up tearing the wire....


Antique, i'm real bad at documenting and photographing things like this....the best place for finding info on how all this stuff like coils and converters work is on the various high-voltage hobby sites and forums. toys like stunguns and strobe lights are very similar to our cdi ignitions


dave

wvarn1957

My Feedback: (3)

Zagnut,

You can calculate the frequency using the following formula:

Time(in seconds)= Resistance (Ohms) X Capicatance (Farads)

This will give you the cycle period in seconds.

For example using a 500 ohm resistor and a 0.47mf capacitor:

500 X .00047 = 0.235 seconds. Dividing 0.235 into 1 gives 4.255 cycles per second(Hz).

c_moore

Hi Zagnut,

I am currently using CH coils.To get a good spark you need at least 350 to 400 Volts.At least in my experiments anyway.

c_moore

Hi MAtt,

This is What I use.#30 Awg for the Secondary,#26 AWG for the Primary and #30AWG for the Feedback. the size of the transformer is 3/4X 1/2

Matthewt

What are the lengths of the wire for the secondary,primary,and feedback? And when you say transformer size, is that the e-core itself or the bobbin size?And will I need to change other parts on the board for this type of transformer to work? I have saved some e-cores from VCR's
TV's and computers,is it possible to use any of these used cores and bobbins?(If I rewind them.)

Matthewt

I have few more questions. The schematic I have calls for a .47 uf 250v Mylar capacitor. Are there other names for this capacitor? Or can anther type of capacitor be substituted in its place?I took this schematic to radio shack, and they did not have this part nor did they know what it is.
Also a 2.2 uf tantalum capacitor is listed, but it does not specify what the volt range is just a old part # which is no good .A last a silicon controlled rectifier which the part # is also no longer good.All the schematic says is RS 1020. And the board has 3 holes for this part to fit in.Can any one help?

ZAGNUT

My Feedback: (1)

forget radio shack and either find a real electronics shop or order online from digikey

a poly cap like digikey part # PF2774-ND would probably be fine in place of the 250 volt mylar. these work for me

the 2.2uF tantalum is probably on the oscillator circuit, right? if so then a voltage rating of about double your battery will be fine and a regular electrolytic cap would probably also work. be sure to observe correct polarity with either

for the SCR you've got about a million choices out there...look through some of the various schematics posted in this thread and pic one you can find easily. just make sure it's rated for high enough voltage and current. think the ones i'm using are rated for 800 volts and 6 amps- found in junk box. use one with a non-sensitive gate if you're using a hall effect trigger


dave

c_moore

When I say 3/4x1/2 I mean the outside dementions of the E core.What type of ignition coil do you plan to use?The Length of the wire is not important.pay attention to the Number of turns.Im sure that most people on this Thread have seen this.

fokker38cc

Hi

Mathewt
yes, you can use ferrites of power supplies of VCR, tv sets, I am using ferrites of old monitors, old power supplies of telephone systems , japanese and german, and also of old power supplies of PC, faxes, of different sizes, BUT my CDI have only two windings, because I am using as switching supply , step up transformer I believe you say, from 6 volts I can reach 400 volts and the best pieces a bit more than 500 volts.
Caution, the sides of ferrites must be clean and the contact surface between halves must be clean, if you have small foreign particles you never reach good output voltage.
I believe you can use it because the power they can manage are big compared with the power comsumption on a spark, you never reach saturation, you are working in the linear stage.
If you like see Amidon ferrites, search in the web, they are fine person and sell ferrites for CDI
also wire.
I have the better coils , more than 500 volts of pot cores OL N30 from EPCOS, a siemens subsidiary
www.epcos.com
my system is like the you see at
www.qsl.net/ariparma/trasfo.htm
but mine start from 6 volts and have a CD4047 cmos oscillator, far better stability than the 555 and the switching transistor is a TIP 31 VERY GOOD BRAND only , throw away cheap chinese, the bridge rectfier you must made of fast recovery diodes.

c moore
You can use any high voltage coil of a moped with CDI, I am using with success coil from Honda Transalp 1993, same as Honda XR 600.
Very sturdy but bigger than of 3W, and this coils are designed to make a spark with low input voltage , my memory fail but I believe I measured a bit more than 100 volts at the capacitor when kicking to start the moped ( DAELIM , honda based moped magneto on Honda transalp coils).
I make it spark with 200 volts output of CDI when I am in the first stage, but after improved and reach 400 volts .
The best I have, more than 500 volts are from a german switched power supply, recycled of old telephone equipment and wounded with wire recicled of old relays of more old telephone equipment , also german, with a hand powered drill, What a technology!

Good luck and better sparks.
sorry my english .
See you later
Jose