your own ignition

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stew79
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Re: your own ignition

Post by stew79 »

sorry beat, i missed your last entry, your diagram is correct. (but on the feed back coil it looks like 40 t ?should be 10t, and you no the small hv cap is only there to stabilize the running of it, if its not joined up to the main ignition cap, and the rest or the ignition. when i prototype things like this i find it easier to break the system down into its separate assemblies, some times if you have a complete, joined up system with a fault some where, its harder to find whats wrong ) although this circuit works ok, i think it can be improved on quite a lot.
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Re: your own ignition

Post by stew79 »

a message to jack gilford, if you can help me fathom out how to read a scope properly, it will help the 12 volt cdi project i am occasionally playing about with. when finished, it is for anyone here to have a go at making for them selves if they want. in brief, there is an imbalance with one of the 5 stages of the cycle of the hartely oscillator. (having done more research on this "simple" device i have found out that its complexity is quite stunning ! it even involves the term "saturation" as part of its working cycle.) using various rheostats, caps, etc i can nearly get it to work how i want. the aim is to regulate output voltage, by its working frequency. (low frequency at stand by and low speed running, but getting higher to keep up with fast running) i can do this to a point, but it can easily runaway, making 10 times the needed voltage. this causes a high current drain, with the main transistor quickly over heating. (the too higher output voltage to the main cap, breaks down the 600 volt thyristor, causing crazy firing of the test coil at a frequency of approx 60hz !!) very spectacular but of no use at all.
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Re: your own ignition

Post by minetymenace »

stew79, are you sure that your circuit is as beat has drawn it (ignoring No of turns)?

Your circuit consists of a coil in series with a 1k resistor (820+82) across a DC source. There is nothing to block the DC, so irrespective of the transistor switching or not, at say 12v you will have 12mA DC flowing through the coil all the time, doing nothing except saturating the coil and wasting energy by generating heat. :shock:

In LC oscillators the coil and the capacitor are normally in parallel or series and the frequency of the oscillator is thus the resonant frequency of the LC circuit (see any LC oscillator circuit on the net). In a Hartley Oscillator, the resonance is sustained by feedback (normally via the centre tap) through the amplifying switching transistor/FET etc (although in Hartley's day it would have been a thermionic valve), for basic examples see Wiki or any electronics tutorial sites.

What has engine speed to do with the circuit?
How does your circuit work?
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Re: your own ignition

Post by stew79 »

hi minety, this is where it all gets too complicated for my brain. are you aware of the 5 stages of the hartely oscillator cycle ? the current from the 2 resistors is always there to start the cycle. during the negative feed back part of the cycle, the resultant power from that coil should balance the current trying to go in, to turn the main transistor completely off (waist full but it works, would be better with field effect transistors as they are voltage driven not current driven, so the resistors would generate less heat, that was going to be the next stage of this project !!!!) the frequency of the oscillator can be changed buy the current balance through these 2 resistors. this is further refined with different sizes of cap over the resistor to earth (the values in the diagram are nominal ones to get it to work, not the best values, and with a fixed frequency like this, as more sparks are needed with more speed, less charge up time for the main cap will mean that the spark power will drop of. the plan is to make a variable frequency oscillator, fully controlled by 2 bc338,s across the main transistor, taking a signal from the out put voltage. thats why i need to be able to read the dam scope thing properly to set all the correct values !!!!!!!
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Re: your own ignition

Post by minetymenace »

stew79, I just don't recognise your circuit as a Hartley Oscillator. The tank capacitor should be across the coil with nothing impeding the resonant path, and the coil should not have a DC path through it. I know a million files eat poo, so poo must therefore taste good, but if you Google: "Hartley Oscillator image", you will see that (unlike your circuit) in every case, the capacitor is across the coil, and there is no quiescent DC path through the coil. To change the frequency of an LC oscillator (for which Hartley won prizes for his designs) you change the resonant frequency of the circuit by changing the value of L and/or C....not the feedback, that changes the amplitude.

As power is drawn, not pushed, why not design your circuit around the maximum power required so that as the demand changes, the circuit doesn't have to? I fear this is not your biggest problem.

Start with the oscillator at a fixed frequency and amplitude, draw an annotated circuit diagram with component references and values, and I will tell you what oscilloscope settings you need and draw you a sketch of the 'scope waveforms to expect. If you put up a picture of your scope and probes I wil tell you where to connect and which knob to turn.
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Re: your own ignition

Post by stew79 »

hi minety, i thought hartely invented several different versions of it ? or is this what others have come up with over the years ? to get a high voltage from a small battery is a fundamental requirement in possibly hundreds of different applications. i thing the second world war helped this enormously with the development of portable radio transmitters, radar, metal detectors, geiger counters, strobe lights, etc, etc. i have in my collection of odd equipment, a portable emergency radio transmitter from early in the war, powered with hand cranked generator. it has a double ended armature with 2 winding's in order to give you low voltage, and 500 volts to power the transmitter. (it must have had an advantage over an oscillator at that time) even a £2.50 "bug zapper tennis racket" from ebay has a simple oscillator capable of generating quit high voltages from 2 small batteries. the secret is to make this higher voltage as efficiently as possible. i think "future techmatic" was a company that worked with the MOD, designing and making metal detector electronics, (among other things) that were very good. "clews" the master bodger of ccm got this firm to make his first battery powered cdi ignition, and the rest is history . from my experimenting i quickly found out the biggest problem with any ignition oscillator is, it isnt just giving you a steady supply to run something like a fluorescent tube light, or a mains tv from a basic inverter. the way it must cope with repeated short circuits (and stall at every firing of the spark) is very hard to recreate unless you have it in a complete ignition system. has this just confused things further ?
stew
ps i am still aiming for a power out put greater than needed, so it can be regulated down when demand is less. the circuit re drawn by beat will work (although to have a 1k res between the hv tvs and the base of the bc338 is slightly kinder to the trans) <213
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Re: your own ignition

Post by minetymenace »

stew79, to fund my motorcycle habit I toil as a freelance electronics engineer. For the last year I have had a contract designing high voltage ignition systems suitable for harsh environments. If you need any help, just ask.
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Re: your own ignition

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hi minety, in my large circle of family and friends, there are several industrial / domestic electricians, (off shore, and submersible robotics, survey etc) 4 highly qualified electronic design, and production engineers, several top toolmaking, cnc , production and design engineers, friends and relatives from many different motor sports as well...........but none of them can help with cdi ignition !!!!!!!!!!!! the common reply is "ignition stuff, thats a bit specialized" some years ago i tried to get some of the top people at a local, but global, electronic manufacturing company to help out with the ccm project. after they had gone over all the evidence, seen some of the non working parts i had at the time, and took in what it needed to do, they all said, "it could never work, it could never have worked in the past, and we cant see how we could help!) that prompted me to join the library ,and do as mush research as i possibly could on this tricky little problem. thats why i am this stage of the journey. to here that you are involved in a similar type of project is amazing !!! if you can help with this project on here, will that compromise the real work you are doing for your job ?
stew
ps i have just bought another 2 channel hameg scope, so i can take up to 5 simultaneous readings from a running ignition system on the test rig.
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Re: your own ignition

Post by stew79 »

been doing some more experimenting, so just for minety, some oscillator circuits that can power a cdi ignition. using up to 3 rheostats on a running ignition, means the wave form of the spark can be observed on the scope. power in put can be compared with spark energy, to arrive at the best values. then the rheostats are disconnected and there values recorded with a meter. this can give the best lowest voltage to start it running, and the best values to safely "stall" every time the ignition fires.
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Re: your own ignition

Post by Mark Cook »

I must admit I do like the glue gunned crocodile quick connects.
Who are you using for the pot cores and coil formers Stewart?
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Re: your own ignition

Post by stew79 »

hi mark, some of my friends who do electronics for a proper job, are quite disturbed by my "wood and super glue" approach to prototyping. i say, if it holds every thing still while i solder it, whats the problem ? so i am glad you approve. as for bobbins i have about 5 or 6 round ones, (25 and 30 dia) and several different size square ones. they have all been wound, and unwound dozens of times. no proper companies were used for anything, its just an interesting subject, to make high voltage efficiently from a dc supply. (really just to power the next Tesla coil project)
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Re: your own ignition

Post by beat »

hi stew,

what type ( size ) Potcore you are using and what frequency is your transister TIP 36 on :?:

beat <201
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Re: your own ignition

Post by stew79 »

hi beat, the pots were from ebay just general purpose things, 25 and 30mm dia.(from a shop in holand?) as for frequency, that depends on the resistance to the base of the trans, and weather there is a 0.5mm core gap or not. (trans can also be an mjl21193) to run a single cylinder engine up to 10000 rpm a just audible frequency from the trans is ok. i was trying to increase the frequency to match engine rpm, but its not necessary. the 12 volt project is finalised for a reliable, efficient, regulated system.(20 ma at rest, 1.5 a at 10000rpm) but as i have no need for it i have been working on a similar setup for a friend with a very tuned, twin turboed 7.2 L v12 jag. cdi will allow him to increase the boost and, or increase the max rev limit. (at the moment the best mdi system he has found cant supply enough spark energy over 5000 rpm) to do away with the dizzy and have 6 cdi coils with twin outputs would be best, but i am still learning. (1400 sparks per second !)
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Re: your own ignition

Post by Mark Cook »

I've just placed an order to have some pot cores made, hope I've got my sums right. Just a month to wait to find out. Oh the things we do just to make a fluorescent lamp driver
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Re: your own ignition

Post by beat »

Mark Cook wrote:make a fluorescent lamp driver
hi mark,
if I get "fluorescent lamp driver" right, - we use to buy them in the supermarket nearby, - as fluorescent lamps are common here in use.... <201


:lol: :lol:


BTW, as " electronic season " has started, guess I have to place a order by my el. part supplier soon....

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Re: your own ignition

Post by Mark Cook »

The circuit required to simply drive a fluorescent tube with 12 volts is very similar to what Stew is doing. Much harder is to strike the tube into life and not burn the ends with the heaters.
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Re: your own ignition

Post by beat »

Mark Cook wrote:fluorescent tube with 12 volts
now I got it....
:idea:

BTW,

I just have placed a order on eBay abouth a thing called
DC DC Boost Converter 8 32V to 45 390V High Voltage ZVS Capacitor Charging Board

Seller is: mhestore2009

it really wonders me how " professionals " are making it. ( if they really do )

the half a docent $ will not killing me if it is unusable.

what are you guys thinking about this Board ??

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Re: your own ignition

Post by minetymenace »

Hi beat, these are notoriously unreliable with a very low MTBF. I'm a little confuse by the cap charging time (about 6 secs for a 2000uF cap)....
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Re: your own ignition

Post by beat »

hi all

I got it in my hand...
cheap and maybe not worth the 6 $ ??
cheap and maybe not worth the 6 $ ??
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Re: your own ignition

Post by beat »

BTW:

2000uF in 6 sec. = 4 uF in 0.012 sec.

8000 rp/m = 4000 sparks/min = 66.66666...sparks/sec.
= 1 spark by 4uF delivered each 0.015 sec.

theoreticly a left over of 0.003 sec for the switching process.

Hmmmmmmm

if this maths is nearly right, - there is a chance....
ore: why not using two of this in parallel ???


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Re: your own ignition

Post by minetymenace »

Been itching to say this for ages....when you are considering fast switching, the inductance of everything is important. Keep all you fast switching wires short, use low inductance techniques in your track layout, and try to buy capacitors with low inductances, do not use wire wound resistors. I have a neat video how to measure the inductance of a capacitor, I'll try and post it soon.

Beat, looks like a fly-back circuit, what is the voltage rating on the electrolytic cap between the pot and the connector? You might want to replace that with a high voltage mica one!
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Re: your own ignition

Post by beat »

thanks minety
minetymenace wrote:looks like a fly-back circuit,
yeas, it seams to be....
minetymenace wrote:what is the voltage rating on the electrolytic cap between the pot and the connector?
you mean the green ones ? they are 10uF and 400 Volts.

but minety, - can you have a look at the shop called ayanhu81's shop please for me??

they sell something nearly with 3 capacitors. costing 9.58 $ and it seams to be a bit stronger.
( once in the shop, print dc-dc converter in to the surch. page 3 at the end it is )
ore do I miss something :?: :?:

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Re: your own ignition

Post by minetymenace »

can you post a link beat, search cam up with ziltch.... <201
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Re: your own ignition

Post by beat »

Don't know how to link things :oops:

in Ebay :

Bildschirmfoto 2016-11-01 um 18.58.54.png
Bildschirmfoto 2016-10-27 um 22.53.36.png
this is the one. 3 capacitors by 400V 10uF

there are some others, delivered with cases.
not shure they will be better....

beat <201

just a Idea: in low revs are higher capacity uF needed, - so maybe switching off one of two by a surtain rev. :?:

will testing it soon..... <216
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Re: your own ignition

Post by beat »

<201 <201 <201
DSCN3301.jpg
using a 6.8uF cap ( 600 V ), it takes 74 ms to reach 400 Volts WHEN I SWITCH THE UNIT ON
not shure jet it will takes the same time when just capacitor will be discharged and unit is continuously running in the background.

using a 1.8 uF cap ( 600 V ), it takes 46 ms to reach 400 V. same condition.
charging the 1.8 uF cap to 200 Volts only is taking 10 ms .

the Voltage out is quite stable as to se:
DSCN3300.jpg
within 300 ms it falls from a peak of 400 V down to 380 Volts, the value the unit is adjusted for now.

guess I have to build a " cap firing " unit first, such as it is then used for produce the spark at the plug...

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Re: your own ignition

Post by stew79 »

hi to mr minety, as i have been reading lots more about oscillators and electronics in general, i can finally answer your question about "the hartley oscillator" its not one !!! a friend from electronics world told me many years ago "thats what that part of your ignition is" he was wrong, its actually half of a "royer" oscillator. royers are "push pull" devices developed many years ago for radio, but with many other uses as well. in making several experimental transformers for the v12 project, i found its easier to separate the two half's wiring for checking that the 4 coils polarity are correct. then joining both sides together when its right. (for full push pull) a left or right hand part is its own oscillator ! (push only) as for the principal of its operation thats very clever, with positive and negative feed back working together beautifully.
stew
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