RE: Scratch Built Ignition???
 

Hi! I have found in here [link]http://www.sportdevices.com/ignition/ignition.htm[/link] this.
http://www.sportdevices.com/ignition/ignition.gif http://www.sportdevices.com/ignition/ignition_TCI.gif
Will this works that you think about?
It will be work on Hall sensor?

RE: Scratch Built Ignition???
 

The first schematic has a high voltage alternator, which produces 200-300 volts. This makes it a bit easier to generate enough high voltage from the spark coil. The second circuit acts on pulsing 12 volts through the spark coil. I'm not sure that it would work, but maybe it does with the right coil. The way the input to the PIC is shown will work with a PIC.

RE: Scratch Built Ignition???
 

Hi Dan,
I just bought a ECHO CS-4400 off of ebay. It has slope advance ignition. I thought that it would include a bunch of additional electronics, when I took the saw apart I found a flywheel and coil simular to other saws. The big difference is that it has three magnets instead of two. The flywheel is 3 15/16" and the coil is mounted on the saw frame. The engine is the one used for the BME 44cc power house, so I am looking forward to testing it with a prop. I ran it in the saw just to confirm the it was a good motor. It had easy starting even with a fouled plug and good transition. It will be interesting to see any difference with the slope advance system. The G-38 and some Redmax saws use three magnets in thr flywheel. I am going to make a bracket to mount the coil. I would like to install a CDI ignition later.

Regards, Dave

RE: Scratch Built Ignition???
 

Hi there. I want to build my own electronic ignition system with variable timing advance for a homelite 45cc or poulan 46cc engine. I'm currently researching to find all the components needed.
I think an easy way to to vary the timing is with a pic chip. I found some interresting magnets at http://www.leevalley.com/hardware/pa...363,42348&ap=1

I'm looking for timing advance values or curves for these engines. I would also like some schematics for ignition systems similar to CH ignition or ZDZ ignitions. Thanks in advance

RE: Scratch Built Ignition???
 

Thanks for the info Dave,

If you are able to run the unit with an automotive timing light, I would appreciate knowing about the advance slope and the total range of the electronic advance in degrees.

Thanks again,
Dan

RE: Scratch Built Ignition???
 

Sigh...
A while ago i was hot about electronic ignition.Well,now with gas cost $2.20(and keep on going up) and methanol cost $2.99(as 6 months ago) i think i will convert everything i got to glow.
For the extra 70 cents a gallon i'll be flying methanol.Yeah i know engine uses about twice as much methanol but saving of weight and ignition cost is obviouse.
Thats my point about scratch built ignition.
Mitty

RE: Scratch Built Ignition???
 

Where do you get methanol for that price?
what about nitro ?

RE: Scratch Built Ignition???
 

I buy methanol in local race shop.Mix 5 gal of methanol($15) with 1 liter of KL100($8) get almost 5.5 gal of 5% oil and 0% nitro.
It's about $4.60 a gal. As few experts out her informed me 5% for the ball bearing engine is safe and healthy so look for yourself.
If you really cheap (like i am :) ) mix 32:1 or 40:1 just like you mix your weedeater fuel.In that case it's even cheaper to fly.
I got cought up with few very important things at work that keep me from flying nowdays but soon i'll be back on trac.Then all my weedeaters will turn in to a methanol engines.
Oh yeah, on one of the weedeaters i used a coupling from hardware store to replace the prop hub.After all thats what it is all about -cheap ,right?:)

RE: Scratch Built Ignition???
 

Yeah I was thinking about going to a gasser because it just killed me everytime I had to spend $15+ per gallon.

With your info I found a place were they sell me 99.9% methanol (these guys even sell to pharmaceutical companies).
With oil, it will cost me about 1/4 of the price.....and at that price I'm getting a nice super tiger.90.
They are really cheap at ecmc.com 150 cnd
Thanks

RE: Scratch Built Ignition???
 

I’m trying to build the (Floyd Carter) capacitive discharge circuit, found in the 80’s RC Modeler magazine .Im wondering if I can use an e-core instead of the toroid core, for faster winding time.
Does any one know if this can be done? I'm trying to save money. Just got married!!!! BROKE.. I have salvaged some e-cores from a TV and VCR’s. No luck on finding any toroids yet. Any help would be greatly appreciated.

RE: Scratch Built Ignition???
 

Yes e-core will work even tho less efficient .But in cdi it won't matter.The size of ecore will be bigger i think.
Ask Marlowe,he outta know for sure.

Mitty

RE: Scratch Built Ignition???
 

alex_scratch_built
Just remember you will use methanol at twice the rate that you will use gas, so even if you can get the same quantity for the same price a 10min flight will still be twice the price but i suppose if you use a smaller engine it wont be so bad.

RE: Scratch Built Ignition???
 

I built one a while back and wound the transformer on a piece of an old ferrite rod that was originally an antenna in a small transistor radio. The e-core should work fine.
W5RA

RE: Scratch Built Ignition???
 

anyone have a scanned copy or pdf of this article? My bride "cleaned" the garage (it's typical of European-bred women) and out went my 30+ year collections of RC magazines.... :(

[:-]

RE: Scratch Built Ignition???
 

I'd like to get a copy too if possible...Please.Or i can scan paper and convrt in PDF if needed.
Mitty

RE: Scratch Built Ignition???
 

I have the article somewhere. If I can find it I'll scan and send if I have the e-mail address.

RE: Scratch Built Ignition???
 

If you go back and look at the first page of this thread, the 5th post down, ANEAT gave the info to look at the article in the RCM archives. I don't know if you can look at it if you are not a subscriber. I do subscribe to RCM. I clicked on the address that he showed, and it came up without asking for any member ID. I do also have a copy of the original magazine, and could possibly scan it, if I can find it.
W5RA

RE: Scratch Built Ignition???
 

You can also find a schematic which is very similar to the one in RCM by looking at the 10th posting of the 9th page of this thread.
W5RA

RE: Scratch Built Ignition???
 

thanks W5RA... got 'em....

I guess you're pretty much up on this stuff :D

[:-]

RE: Scratch Built Ignition???
 

Thanks for the help. How many wraps and and size wire should I use with the E-core, and does it use a socondary,primary,and feedback like the toroid?What size e-core should be used?The plan I have for winding the toroid does not show the size of the core to be used.The secondary 450 turns #34 (29feet)primary#24 15 turns feedback#30 6 turns.The plan gives a old part # for core to a company that is no longer in buisness (fuji-max usa, 2747 n. Giddings, visalia, Ca. 93291.By the way I think Ive found a core in a old computer how do I know if it is the right kind.and does size matter?

RE: Scratch Built Ignition???
 

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

RE: Scratch Built Ignition???
 

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).

RE: Scratch Built Ignition???
 

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

RE: Scratch Built Ignition???
 

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

RE: Scratch Built Ignition???
 

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

RE: Scratch Built Ignition???
 

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

RE: Scratch Built Ignition???
 

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.

RE: Scratch Built Ignition???
 

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.

RE: Scratch Built Ignition???
 

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

RE: Scratch Built Ignition???
 

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.

RE: Scratch Built Ignition???
 

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

RE: Scratch Built Ignition???
 

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

RE: Scratch Built Ignition???
 

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.

RE: Scratch Built Ignition???
 

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?

RE: Scratch Built Ignition???
 

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..

RE: Scratch Built Ignition???
 

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

RE: Scratch Built Ignition???
 

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

RE: Scratch Built Ignition???
 

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).

RE: Scratch Built Ignition???
 

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.

RE: Scratch Built Ignition???
 

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