CDI Capacitor Discharge Ignition Circuit Demo

[@thierryavikian3663]

The best electronic teacher I never had in my life ! Thank you so much to speak so slowly for foreigners ( like me). Everything is so clear. Thierry ( from France)

[@AllAmericanFiveRadio]

Thank you Thierry! I hope this video was helpful. Thanks again, and your welcome.

[@jgmo53]

Sure wish I had this when I was a mechanic's instructor. This is one of the most concise, well conceived and presented little video "vignettes" on this subject I have ever seen. WELL DONE SIR! Thank YOU!

[@AllAmericanFiveRadio]

Thanks Jim Dixon

[@ExplosiveAnyThing]

I would like to add a note here, because it seems some people having trouble understanding it. Not all cdi's have this excitor coil, some old cdi's have that. Most of them nowdays have an inverter build in. These kinds of cdi's gets their power directly from the battery.

[@windsurfer3329]

I have been teaching electronics at a local university, and will recommend my students to watch this video even though we don't go into power electronics. This is an excellent video describing the basics of a CDI system. There is supposed to be a signal conditioning circuit in the pulse rotator path that terminates at the SCR gate; its main function is to clean/filter the spikes from the triggering mechanism. All in all your explanation is very clear, and concise. Thanks for uploading the video.

[@AllAmericanFiveRadio]

Thank you. I'm glad you find this video worthwhile watching and useful, and hope your students will also.

[@fernandoramirez-dp5jx]

This is the best explanation i have seen so far. Thanks

[@januarioqueiroz3122]

...and even his voice is so pleasant, a calm voice that is good to be heard!

[@harryohanson]

Such an awesome job! I am very visual learner and I’ll be watching this repeatedly. Thank you!!!

[@AllAmericanFiveRadio]

I'm glad this video is helping. THANKS!

[@HavokTheorem]

Highly invaluable video, I saved a lot of time and money making my own CDI circuit from basically exactly this schematic for a 125cc dirt bike. 100ohm resistor, 1n4007 diodes, 1uf 250v cap and a BT169D thyristor.

[@pedrookra]

Hi good work frank this project, I need to make this CDI of my dirt bike he is a suzuki rm 125 92 you know its work on my motorcycle? send me a e-mail please i realy need this project help me please, sende from: [e-mail]

[@AllAmericanFiveRadio]

Usually the capacitor is the part that fails first.

[@pedrookra]

HI All American Five today I opened an original dirt bike CDI, I can see to have a 250v orange capacitor, I am from Brazil, but I did not think to buy this cdi here and when I thought it was very expensive 450 500 $ How Do I understand enough of electronics to make my own cdi

[@AllAmericanFiveRadio]

I'm glad the video helped

[@pedrookra]

Do you believe this circuit meets my dirt bike? because shee reaches 11 000 rpm two stroke power monocylinder

[@whydahell3816]

Glad you made this. Learning all the components and their contributions is hard enough but seeing any changes in a real time model, greatly helps

[@AllAmericanFiveRadio]

I'm glad you found this video useful. Thank you, and your welcome.

[@W1RMD]

I normally watch your radio videos. My 1984 Honda "Big Red" stopped running. What a pleasant surprise to find YOUR video covering this! Great job as always. The Big Red is running now, by the way. Thanks again my friend!

[@AllAmericanFiveRadio]

Thanks. I'm glad this video helped.

[@sivucit]

Thanks Rick for uploading this video,, little bit of insight for others. Pulse coil is the one which would trigger when piston comes to top dead center in motor bikes. IN four stroke engine, u have intake(getting GA), compression(compress the GAS), spark(spark the compressed gas) and exhaust as four events, u want to spark the engine at the top of compression stroke, pulse coil will provide pulse exactly at that stage.. In Cars Transistor is used to pulse the coil ground and power is steady

[@bmck9097]

Excellent video, thank you for taking the time to do this. I now completely understand how this system works. My 50 HP merc outboard uses this system.

[@spideychad4901]

Ha, brilliant! My mechanic just said my boat needed a trigger today, so when I found your video, it explained EXACTLY the info I wanted to understand. Kudos to you sir!!!!

[@AllAmericanFiveRadio]

Thanks

[@190055joe]

I put a CDI system in a Ford 4 cylinder Cortina many years ago and straight away noticed more power and better idling , except one night i noticed that the engine was idling roughly when I opened the hood it looked like a Xmas tree, sparks leaking from all over the spark plug leads .The higher induced voltages must of been to much for the leads , the simple solution then was to buy HV insulating sleeve and install the leads inside.

[@AllAmericanFiveRadio]

+190055joe THANKS

[@AllAmericanFiveRadio]

Thanks Daniel, I've been busy working on a 50,000 Watt transmitter. Both three-phase circuit breakers failed. The station was off the air since Wednesday afternoon, got the parts in today and she's back on the air. Glad the video was helpful. Rick

[@ronbarbi2008]

Great video on operation........Thanks for the explanation!

[@joerossi43]

I have been trying to learn and diagnose a small engine with no spark. these type videos are great ! Im almost amazed at the effort people put into these videos and the value that we all can get out of them. Im no engine or electronics expert but i know enough to fix some things and other times royally ruin things. I might be totally wrong but it doesn't make sense to me that the ignition's primary coil is grounded directly. I figured it would get the solid ground thru the gate(SCR/transistor or whatever it is)

[@Biokemist-o3k]

Yes even 8 years later. fantastic!!

[@protickchakraborty]

How to use eliminate,

[@protickchakraborty]

And ,did you know how to create a klin spark ignition for ceramic factory

[@sivucit]

yes modern car have Cam sensor(provides which cylinder is top), and crank sensor(provides whether cylinder is approaching top dead or not) is fed to ECM/PCM, then PCM will send pulse signal to ICM(igniter) which will momentarily supply ground(using transistor switch on / off) to the ground side of the coil, note positive is 12 volt connected all the time, this makes a spark..

[@blink-klippie]

thank you very much for such a clear concise description of how the scr based cdi works.

[@landlordhan9148]

an excellent explanation. thank you. I had no idead what vehicle ignition was until yesterday, but watching this video, I can totally comprehend what vehicle ignition is and how CDI works.

[@AllAmericanFiveRadio]

THANKS

[@gmaclaren]

Excellent description. Just what I was looking for. It's difficult for me to comprehend how my new CDI distributor on my 1974 Ford 302 V-8 manages to "trigger" with the components I see withing the distributor cap. Not that it makes an difference, but mine is a marine application. Thank you very much for the description.

[@TheJoew19972]

the silicone rectifier or SCR is a electric one way gate that's controlled by the pulsar coil.

[@georgechambless2719]

This is how my Honda Rebel 250 ignition system works. Thank you for the visual explanation!

[@AllAmericanFiveRadio]

Thanks and your welcome.

[@AllAmericanFiveRadio]

Yes without the diode operating the ignition stop switch would kill the engine and stop the ignition from firing. Without the diode there would be twice as much current through the exciter coil which also means twice as much heat. The designer of the circuit has determine that there would be no damage to the exciter coil by adding a diode, and ignition stop switch still stops the ignition from firing.

[@47f0]

Interesting. I was trying to figure out an Amazon review for a small engine accessory coil to provide 12 volts for gas engine bicycle lighting. This reviewer said that just adding the aftermarket coil (approx 180 degrees from the ignition charge coil) kept his engine from running more than 3,000 rpm. We used to do this exact trick with old Ducati and other euro "scrambler" dirt bikes that only had one magneto coil so we could get some lighting, and it was never a problem. Of course, those were the days of separate spark coils with contact breaker points (and incandescent lights that didn't care about the non-rectified AC pulse from the lighting coil), but still, I'm having a hard time understanding how adding another coil would possibly have any affect on the CDI system. The aftermarket coil is grounded to the engine and has one power lead coming from the other end of the coil, so both the ignition coil and the aftermarket lighting coil share the engine block as a ground - but that shouldn't be an issue... should it? Strange, eh?

[@AllAmericanFiveRadio]

T would need to see the circuit.

[@peterjuhasz5143]

Thank You for this demonstration, everything was clear and understandable! Great job!

[@AllAmericanFiveRadio]

Thank you!

[@bvnj123]

Great explanation, thank you. Just for reference SCR stands for Silicon Controlled Rectifier.

[@AllAmericanFiveRadio]

Thanks

[@JoelArseneaultYouTube]

Great explanation ! I envy your ability to simplify this to the point where anyone could understand... even after watching your video, I couldn't explain it so clearly. I get so caught up on details... I'd go off on a rant about timing advance curves, 2 cycle vs 4 cycle, coil fed vs battery fed ... and I'd walk frustrated and with the other person more confused than when I started.

[@AllAmericanFiveRadio]

Thanks for your comment.

[@sivucit]

In addition to my other note, cars don't use CDI(capacitor discharge unit), rather it uses Transistor switching the ground side, with positive connected to positive side all the time.. hope my 2 notes would have made sense.. CDI is used in Motor bikes and transistor switching is used in Cars.

[@vivianoni9565]

CDI isn't the "black box" you thought it was. An SCR, v. a transistor, is used to ensure a more complete discharge of the capacitor to induce more voltage in the secondary coil. An SCR conducts until a reverse voltage is applied to its gate or, in this case, the capacitor fully discharges.

[@AllAmericanFiveRadio]

Silicon Control Rectifier SCR Basic AC Circuit kzbin.info/www/bejne/amarZX2ViJplj5Y

[@donovanlucibello379]

Wow, what a gift this video is to me. Great explanation, thank you!

[@AllAmericanFiveRadio]

Thanks and your welcome.

[@acestudioscouk-Ace-G0ACE]

You have a great way of explaning things, thank-you.

[@AllAmericanFiveRadio]

Thanks you, and your welcome.

[@dwtees]

No pulse coil in car's. I would guess this is an ignition system for a lawnmower but this is just a guess. Modern automotive (and motorcycle) ignition systems are slightly more complex and use a crank sensor and a camshaft sensor (faster start times) and do not generate their own power from a magneto as this demo shows. All the other concepts are the same. Very nice demo Rick.

[@AllAmericanFiveRadio]

The ground is the same ground everywhere just think of it as a wire. When the capacitor is charging the ground is negative, that negative goes up through the primary of the ignition coil making the right side of the capacitor negative. That makes the left side of the capacitor positive. Electrons will flow through a diode device against the arrow.

[@juergenscholl2843]

While looking at it with the electron flow view it makes perfect sense. Though it seems to confuse those eyeing the ground location of the capacitor/primary coil leg from a conventional current flow point of view.

[@n1chp]

Rich, Great information. This helps to understand various components. Now it also helps to see how the function in a radio or any other device. 73, Mike

[@andyvh1959]

GREAT description of how a CDI works, easy to understand. I need to build a CDI for a motorcycle engine that uses two trigger coils. One at 10 BDTC and another at 35 BTDC. I assume I'd duplicate the SCR to the trigger circuit. But how would it "switch" to the 35 BTDC trigger as the engine speeds up? I need the advance to occur before 2,500 rpm.

[@nomanpathan221]

Dear Sir, you are too Experienced, appreciate your work.

[@AllAmericanFiveRadio]

THANK YOU!

[@cristianpopescu78]

The Best Video on KZbin !

[@AllAmericanFiveRadio]

THANK YOU!

[@rockiemountin7535]

Great video very clear and to the point with easy to understand illustration thank you sir👍

[@AllAmericanFiveRadio]

Thanks

[@blancolirio]

Great job! did you put all this animation together too?

[@AllAmericanFiveRadio]

Yes

[@blancolirio]

Excellent! I will use your video for reference when I get to this subject on motorcycle electrical systems. This is the quality of tutorial I remember from Airframe and Powerplant mechanics school years ago. (Mostly great quality WWII training films). JB

[@duncanjaxson8422]

You prolly dont give a shit but does anybody know a method to get back into an instagram account..? I somehow lost the account password. I appreciate any tricks you can offer me.

[@kasejayden9388]

@Duncan Jaxson Instablaster ;)

[@duncanjaxson8422]

@Kase Jayden thanks so much for your reply. I got to the site through google and I'm in the hacking process now. Seems to take quite some time so I will reply here later when my account password hopefully is recovered.

[@shaundavis8522]

the best explanation and workind of this circuit i have seen. my question on this is a ac cdi what is difference between dc/ac operation other tha alternating and direct?

[@AllAmericanFiveRadio]

Silicon Control Rectifier SCR Basic AC Circuit kzbin.info/www/bejne/amarZX2ViJplj5Y Silicon Control Rectifier SCR Basic DC Circuit kzbin.info/www/bejne/f57chaqQfL9ggtU

[@sivucit]

This circuit is used in motor bikes. If you want to kill the engine, u use stop switch which will short the exciter coil to ground providing no current to spark plug and ur engine comes to stop.

[@sivucit]

Rick, I am not clear on one area, when capacitor is charging one side will be negatively charged and other side will be positive.. please advise which side is what and how this is animated during discharge, Thanks so much for uploading this video.. I gave little insight in my othe note..

[@bennydwars8507]

This explanation is really perfect

[@AllAmericanFiveRadio]

Thanks. Your welcome.

[@robertbrandywine]

When the capacitor discharges, why doesn't the electricty just flow to the frame via the ground that is between the SCR and the primary coil?

[@AllAmericanFiveRadio]

When the capacitor is charged, think of it like a battery. Positive on the left and negative on the right. When the SCR fires think of it like a wire. Now you have Positive and Negative voltage across the primary of the ignition coil.

[@AllAmericanFiveRadio]

Electrons flow from negative to positive. When the capacitor is charged and the SCR fires the electrons flow from the right side of the capacitor through the primary of the ignition coil up through the SCR to the positive side of the capacitor completing the closed circuit.

[@robertbrandywine]

So electons flowing down from the right side of the capacitor don't see the ground as attractive and are eager (so to speak) to flow up to the left side of the capacitor.

[@jarelnomeh2345]

@@robertbrandywine Yes. Except it's the magnetic field that shifts, not the electrons.

[@duncanwright4509]

Because the current will always take the easiest and quickest way back to the source it came from. Which would be the capacitor at the time of ignition. Plus the magneto is between North and south Pole when trigger is engaged. So current wouldn't flow through the ground back to the excitor coil. But it will flow through ground back to the trigger coil.

[@carabela125]

Great informative video. I have a CDI on an older motorcycle. It only makes a spark once when I push the stop button and the rest of the time nothing. I'm thinking either the SCR is bad or the trigger coil is bad and the stop button is actually discharging the capacitor.

[@AllAmericanFiveRadio]

That could be. Most of the time the parts that goes bad are the capacitors. Good luck.

[@TheBogomips]

Excellent Demo, should be a teacher.

[@AllAmericanFiveRadio]

Thanks and your welcome.

[@MickeyD2012]

FANTASTIC explanation.

[@AllAmericanFiveRadio]

Thanks

[@nobleox4687]

Thanks for the demo was wondering how I could reverse engineer this and I think I can now. I have a bank of coils discharging into a network of caps. I then want to discharge these caps while effectively swapping the coils onto another bank of caps so I can charge these while discharging the other bank then swapping back to the other bank and then the whole sequence repeats. Just one query shouldnt the primary coils emf collapse as the cap discharges then induce into the secondary coil and across the spark gap?

[@tryhardtkm1248]

Thanks for clarifying how it works. This helps me a lot

[@AllAmericanFiveRadio]

Glad it helped. Thanks, and your welcome.

[@waynerp5219]

Hi again. I have a link to a cdi I think I can use. I was going to mirror the circuit to get two trigger inputs and two outputs. The original mercury circuit does exactly that but uses two unidentifiable transistors to dump the charge instead of an scr. Do you think it can be done with this circuit? Many thanks in advance for looking

[@tellmesomething2go]

Very nice of you. The best compliment. " I got it ".Thank you.

[@obtron]

simple and straight to the point, thanks

[@AllAmericanFiveRadio]

Thank you, and your welcome.

[@vespadano1979]

Wouldn't the polarity be the opposite of what is shown? I would think the negative part of the cycle would be feeding electrons to the capacitor since electrons have a negative charge.

[@AllAmericanFiveRadio]

A rectifier (diode) only allows current to flow in one direction. To utilize the other half of the AC cycle, a diode bridge would be used (four diodes), and the circuit would also need to be reconfigured. Google “diode bridge”.

[@ChuddleBuggy]

Hello sir. Thank you for helping us along understand some of the mysteries of modern electrical automotive systems. I have a question if you don't mind. In a typical application of the CDI, how many "charge cycles' would you say is necessary to create enough charge in the capacitor? I ask because I really wonder how charging the capacitor is accomplished on say a single cylinder 2 stroke motorcycle engine. If a 2 stroke fires every single revolution of the crank shaft, and the CDI magnet system is tied to its rotation, then you pretty much only have 1 charge cycle (edit: 2 charge cycles) available for charging the capacitor. That is unless you use a gear system to speed up the shaft for the magnet system.

[@AllAmericanFiveRadio]

Don't know, the question was how does a CDI work. Give me a motor model and it's circuit. I'll try to explain the circuit.

[@nirodper]

Well, the magneto rotor has multiple poles so there are many "charge cycles" per revolution. Also the pulse coil is usually on the flywheel so even 4 stroke bikes have 1 spark per revolution, a "wasted spark"

[@kevinhermi9861]

Just confused it looks lile the capacitor isnt grounding on the earth side? Wouldnt it ground and than have a negative charge on that plate?

[@AllAmericanFiveRadio]

When the SCR fires it is like a wire, and that supplies the ground. Silicon Control Rectifier SCR Basic AC Circuit kzbin.info/www/bejne/amarZX2ViJplj5Y

[@MA-kt8ly]

Doesn't spark occur when the field collapses, not when the coil is being charged by the capacitor..e.g. after the trigger is past the trigger point ?

[@AllAmericanFiveRadio]

Transformer Basic Parts & Function kzbin.info/www/bejne/p2S8mZWrnL6dgLs Transformers, a few basics kzbin.info/www/bejne/i6erdISprNOde8k Transformers, basic phasing kzbin.info/www/bejne/eIOlooiHhbGeY68

[@TornadoCAN99]

What I don't understand is how the SCR gate "closing" to allow current flow to ground along the non-primary coil path causes an increase in the primary such that the secondary is energized. I thought it was the collapse of the primary coil EMF field that triggers the voltage jump in the secondary. Is that not correct? Does the SCR gate closing allow the capacitor to discharge along the alternate path instead of through the primary coil and that triggers the EMF collapse & induces secondary coil voltage? If this is so, then I think your animation needs a slight change, showing the red primary path changing to black/unpowered during the trigger point.

[@AllAmericanFiveRadio]

+TornadoCAN99 Silicon Control Rectifier SCR Basic AC Circuit kzbin.info/www/bejne/amarZX2ViJplj5Y Silicon Control Rectifier SCR Basic DC Circuit kzbin.info/www/bejne/f57chaqQfL9ggtU Transformers, a few basics kzbin.info/www/bejne/i6erdISprNOde8k Transformer Basic Parts & Function kzbin.info/www/bejne/p2S8mZWrnL6dgLs Impedance, Back EMF, AC Resistance kzbin.info/www/bejne/r2KUhJWjjbWMZ5o

[@markkinsler4333]

Note that the magnetic field from the primary coil penetrates the secondary coil as well. Thus the change in the primary's magnetic field is also a change in the secondary's field, and a rapid change of magnetic field in any coil produces a high voltage at that coil's terminals (in this case, the spark plug's electrodes.)

[@EverybodyLovesMoe]

Hello, what a great explanation of the cdi using that drawing. I do not have a wiring diagram of my CDI. What brought me here was an issue with my ATV whereby I have capacitor voltage (300v) at the primary of my coil all the time. I have a dc system and I'm unsure if the CDI is bad because the SCR is and being triggered all the time, or there is some other issue. Its a strange issue and I'm not alone as many have mentioned this issue but unfortunately I have yet to find an answer. Any light that you could shine would be extremely helpful for one wandering around in the dark.

[@AllAmericanFiveRadio]

If the SCR is good, it needs to be turned ON and then turned OFF. To troubleshot a circuit you need to know how each component functions. I did a viedo on a SCR, it may help you understand your circuit. Silicon Control Rectifier SCR Basic AC Circuit kzbin.info/www/bejne/amarZX2ViJplj5Y

[@EverybodyLovesMoe]

@@AllAmericanFiveRadio Thank you so much for this. I will check it out. It would seem my SCR is always triggered on which surprises me because I thought it would fail open.

[@Ducktruckful]

In the trigger coil, is the magnet on the rotor or in the trigger coil? having trouble understanding how pulse is making ac voltage.

[@AllAmericanFiveRadio]

Capacitors, DC and AC Current kzbin.info/www/bejne/hHrRpWSJqJiph5Y AC Alternating Current, for the Beginner kzbin.info/www/bejne/rofFooB8oN6ojqs Transformer Basic Parts & Function kzbin.info/www/bejne/p2S8mZWrnL6dgLs

[@krisea3807]

Excellent video to understand how CDI functions along with magneto coil and spark plug.

[@AllAmericanFiveRadio]

Thanks

[@dalenassar9152]

...so in a CDI ignition, the spark plug fires when the SCR switches the primary circuit "ON".? I have seen other systems where the firing circuit arrangement is such that the spark plug fires on the RELEASE of the primary voltage. Does this one fire the plug on the RISE of the PRIMARY coil (thus the RISE of the secondary)? THIS MAKES SENSE--I even tried it and it works fine!

[@AllAmericanFiveRadio]

On the Rise.

[@charlesdickens6706]

....it's interesting. Top explanation was given in our homegrown Australia Electronics magazine 51 years ago and revisited in 1975. ..In conventional Kettering ignition system it is the sudden collapse of the built up magnetic field in the coil which built up in say period of ½ a millisecond collapsing in say ½ a microsecond that generates around 400 volts in primary of ignition coil ( (this phenomena for voltage boost isn't so familiar to many )) which then is instantly stepped up to around say 30 kilovolts by familiar transformer action of coil..With cdi however the 400 volts already is supplied available thus merely needs to be dumped by capacitor action across the primary instantaneously, and capacitors are very good for instantaneous dumping , a 1uf capacitor rated for at least 400 volts is plenty for high energy sparks up into very high revolutions for multi cylinder engines...Also cos it's the effect of forced voltage feed instead of magnetic collapse it turns out that the polarity of the spark is changed. The ideal is for the centre electrode to be negative cos it's hotter,, along lines of vacuum tubes,, but not a big deal . .gotta mention too maybe that in Kettering ignition that it's initially 12 volts across the primary that builds up to 400 upon magnetic collapse when ignition points break contact.

[@ricardocalles140]

If I'm understanding this correctly, the maximum voltage that the capacitor can charge to is equal to the maximum voltage produced by the stator coil (excitor). Is this correct? From what other folks have said, on scooters at least, the stator coils produce around 60 - 100 volts.

[@AllAmericanFiveRadio]

Yes that's correct

[@CalgaryWhistleMan]

Good video and explanation but the one thing that I feel is missing is an explanation of how the collapsing magnetic field in the primary winding relates to a spark being generated.

[@AllAmericanFiveRadio]

Transformer Basic Parts & Function kzbin.info/www/bejne/p2S8mZWrnL6dgLs Transformers, a few basics kzbin.info/www/bejne/i6erdISprNOde8k Impedance, Back EMF, AC Resistance kzbin.info/www/bejne/r2KUhJWjjbWMZ5o

[@markkinsler4333]

Recall that primary and secondary are wound on the same core. A sudden drop in the primary's magnetic field produces the same drop in the secondary's field. Thus the secondary's terminals develop a voltage across them that is proportional to the rate of change of the magnetic field.

[@DangarMarine]

Thank you for your explanation.

[@busdriver9007]

how many acv will the trigger coil make when trying to start it?????

[@gtaagente]

Thats a analogic CDI, today we use DIGITAL CDI , always good video very clean diagram!

[@AllAmericanFiveRadio]

Send me a diagram of a digital CDI. Thanks.

[@collinmurphy1903]

Whats the resistor for? And what would it's rating be? Is to stop current from the trigger or is it to stop current from the charging magnet?

[@AllAmericanFiveRadio]

The resistor is to keep from over driving the gate.

[@kelton5020]

If there's current flowing through the primary coil even with the trigger off, what's stopping the voltage from being stepped up to the secondary coil and firing?

[@AllAmericanFiveRadio]

When the capacitor is charging the current is not strong enough to produce a spark.

[@Mike-ry4ti]

Great video, so if I'm right, the exciter coil timing is irrelevant but the trigger timing is critical?

[@AllAmericanFiveRadio]

The capacitor needs to be charged before the SCR fires.

[@bobmccluskey6796]

Very nice illustration. THANKS!

[@AllAmericanFiveRadio]

Thanks, and your welcome.

[@TroyaE117]

Good explanation. I take it that on a motorcycle with a battery, that the battery serves in place of the exciter coil?

[@AllAmericanFiveRadio]

+TroyaE117 Thanks I would need to see the circuit drawing

[@r.t.elangovanr.t.elangovan6792]

I have one doubt from your schematic, weather battery is needed absolutely .Or the magneto is enough to produce power to charge the capacitor and work to the dynamics of the ignition system pl.

[@rickabrams3422]

Which program did you use for this animation?

[@AllAmericanFiveRadio]

FreeHand 11, PhotoShop Elements, Premier Elements

[@louispatroons4485]

thank you very helpful. But what powers the pulse rotor and excitor coil? Just the crank?

[@AllAmericanFiveRadio]

The running engine

[@MrJAG1156]

Good video, excellent visualization. Thank you

[@AllAmericanFiveRadio]

Thanks

[@itsoktolaugh9526]

Does this mean that the CDI boxes are standardized or is each one unique to the motor they fire? I'm having trouble finding a replacement for my CDI and was wondering if it could be remade easily.

[@AllAmericanFiveRadio]

I would not think this is a standard.

[@track1219]

Is the scr a silicon controlled rectifier? Is it a transistor? If it is both, why does it have 2 names?

[@AllAmericanFiveRadio]

It's a rectifier controlled by a Gate. The Gate turns the rectifier ON.

[@gurtobe]

Great animation! What role does the kill switch diode play? Would the switch still ground and kill the circuit without the diode?

[@coeniefourie9338]

Excellent explanation, just one question, the voltage going to the primary coil is it ac ot dc?

[@AllAmericanFiveRadio]

It's a DC pulse and the ignition transformer adds AC components.

[@unrealcyberfly]

I would like to stop the spark plug from firing using an Arduino. Using the ignition stop switch seems to be difficult because it is high voltage. As an alternative I could disconnect the trigger wire from the CDI. Would disconnecting the trigger wire while the engine is running damage the CDI?

[@AllAmericanFiveRadio]

If you control the Gate of the SCR that may work, but I am wondering if the capacitor may over charge.

[@unrealcyberfly]

@@AllAmericanFiveRadio Thanks for the fast reply. I did some more reading and found out about mosfets that can deal with high voltages like 400+ volts. Guess that could be an idea. Or maybe just an old school mechanical relay.

Nice video. As is can see it, the function of the ignition pulser is triggering the gate of the SCR. This means that current in the wires of the pulser is actually under 1A. Am I right???

[@AllAmericanFiveRadio]

Jovann Pérez Yes, the gate current would be very small.

AllAmericanFiveRadio I checked the flowing current thru the wires of the ignition pulser. As u said and I expected it was a little one. 1.5A are required to strart the engine of and 200cc motorcycle. Thanks for your excellent video.

[@patpintelon8607]

Nice explanation. You have an idea how to take care (with microcontroller) that the advance is function of the RPM on an engine without battery (F4B Yamaha without starter or battery)

[@AllAmericanFiveRadio]

If you can get me the schematic I might be able to help.

[@patpintelon8607]

@@AllAmericanFiveRadio Thats my problem , I dont find a schematic...

[@patpintelon8607]

I made a first LTSpice simulation. Can I post this to U

[@AllAmericanFiveRadio]

@@patpintelon8607 Sure

[@patpintelon8607]

@@AllAmericanFiveRadio Dou you have an idea of the power (V/currrent) generated by a one magnet flywheel (hand cranking) at the RPM of eg. 160 (lower is nor followed by a spark I read in the workshop manual). And what should be the pickup coil windings (number/gauge) to be able to use this energy for the charging of the capacitor and a elco serving as power source for the microcontroller (eg.MSP430)

[@subramanir8438]

If the trigger is given to the SCR not only while starting the bike, does it mean that CDI is required even for running the bike smoothly? My motorcycle under cold conditions burps out for about 5-10 minutes past starting and switches off while the throttle is not revved (I set the idling to its best form but this still happens). Because of this fuel efficiency has severely been plummeted, do you think there might be a problem in the CDI. (I kind of related this to the CDI because my bike tremendously burps out through the silencer whenever i start).

[@azopene]

Do you really need a diode in the ignition stop switch?

[@AllAmericanFiveRadio]

It does half the current through the Excitor Coil. That should extend the life of the coil.

[@tomsparks3259]

Great video! So what makes the SCR shut off? Is there some sort of flyback current from the ignition coil that reverse biases the SCR?

[@AllAmericanFiveRadio]

Silicon Control Rectifier SCR Basic DC Circuit kzbin.info/www/bejne/f57chaqQfL9ggtU Silicon Control Rectifier SCR Basic AC Circuit kzbin.info/www/bejne/amarZX2ViJplj5Y

[@jonganzer7478]

Hi Rick, Thank you for going to all the trouble to make this up and help a lot of people. One thought - you keep saying the capacitor is "storing voltage", or "a little more voltage is put into the capacitor" - I think what we mean is storing amperage, or storing current? I don't think capacitors store voltage, correct? Please correct me if I'm wrong. Thanks!

[@AllAmericanFiveRadio]

It's both. When the capacitor is charging or discharging there is current. When the capacitor is charged there is no current, just stored voltage

[@markhb3346]

Have you any experience with looking at ignition patterns of a CDI system on an oscilloscope ?

[@AllAmericanFiveRadio]

No I don't. A KZbinr asked me to explain this circuit.

[@markhb3346]

@@AllAmericanFiveRadio ok , I'm a career automotive tech who works for a fleet shop . We have a bunch of ATVs and UTVs that I recently have been assigned to work on . On the automotive side I use an Oscilloscope to help diagnose ignition system issues as well as many other issues . I hooked my scope up to a Yamaha rhino with the 660cc in it and the pattern I got looked nothing like an automotive ignition pattern .. So I been searching for any resources to help confirm my theory of how this system fires and how to interpret the scope pattern for troubleshooting purposes .

[@1RobVG]

Excellent.Thank you! I'm working on a motorcycle. I'm not sure what the "rotating magnet" is that charges the coil? Could you clarify?

[@jacklowe5045]

***** Not sure about other bikes but in these small 125cc's and 140cc's etc the flywheel has the magnets in it, and it is the flywheel that rotates around the coils

[@markkinsler4333]

On your flywheel or perhaps the other end of the crankshaft.

[@robertbrandywine]

Is the pulse rotor the same as the pulse generator? Is the excitor coil the stator and rotor?

[@AllAmericanFiveRadio]

The thing to do is to look at what part is doing on the engine. The manufacturer can call the parts anything they want, usually because of copyright/patent infringements.

[@Toolman10000]

Question for you. I’m trying to get a waveform of a coil on the system you just demonstrated. Is it possible ? And what should I see.?

[@AllAmericanFiveRadio]

Thank you. You would need a high voltage test oscilloscope test probe. The probe would have to handle several thousand volts so that you do not damage the oscilloscope. GOOGLE “oscilloscope spark plug probe” and “Images for oscilloscope spark plug probe”.

[@Toolman10000]

@@AllAmericanFiveRadio ok. I was actually trying to probe the primary side. My scope can handle 1000 volts. I know the primary puts out about 250 volts when running. Thanks.

[@AllAmericanFiveRadio]

@@Toolman10000 It will look similar to the secondary, lower voltage. but 180 degrees out of phase.

[@NeptuneWashPros]

if the crank were rotating the opposite direction than what the cdi unit called for, would it still work? thanks

[@AllAmericanFiveRadio]

+tjmars37 Yes it would still work. When the crank turns in one direction + - + - + - voltage is made, when the crank turns in the other direction - + - + - + voltage is made. This circuit is using only half, the + half and it is created in both directions.

[@NeptuneWashPros]

+AllAmericanFiveRadio thank you

[@johnf3326]

Could you run it from 6 or 12v dc battery? Or is AC (no current cycle through diode) necessary to enable the SCR to shut off after it has been triggered?

[@AllAmericanFiveRadio]

You may be able to run this on a battery but it would be a large design change.

[@dalenassar9152]

Thanks, Does firing on the -expanding- magnet field, produce the same spark energy as firing on the -collapsing- magnet field?

[@AllAmericanFiveRadio]

I'm doing an experiment, charging a capacitor and then discharging it on a primary of a transformer and looking at the secondary with a oscilloscope. Get back to you soon.

[@dalenassar9152]

Thanks so much--that data would be EXTREMELY helpful!! Today I have actually started the first stages of construction. The B-Field section is the final part--I plan on using an automotive ignition coil, but have several options (which I would rather NOT use)

[@harrykuncoro5218]

Thank you, with the video simulator above, I came to understand how the CDI works.

[@AllAmericanFiveRadio]

Thanks

[@vanivasil2718]

Doesn’t that ground below the capacitor discharge the capacitor and why Thank You

[@AllAmericanFiveRadio]

When the SCR fires there is a ground on both sides. That is when it discharges.

[@kayinkk2011]

THANKS FOR THE CLEAR EXPLANATION

[@AllAmericanFiveRadio]

Thanks

[@Ducktruckful]

what kind of charge comes out of cdi box to coil pos? is there a way to measure this? Or is it a MFD. charge like cap.?

[@AllAmericanFiveRadio]

Should be able to measure it with an oscilloscope.

[@oilmaninpowell]

On the old 2 stroke motorcycles I'm playing with, there seems to be no mechanical advance. Do some electronic ignition circuits have a circuit that effects ignition advance? Or on these motors is spark advance a fixed value.

[@AllAmericanFiveRadio]

oilmaninpowell There are ignition systems that adjust spark advance with engine speed.

[@oilmaninpowell]

Interesting reading! Thank you!

[@pedrookra]

Hi my friend, good video, I like to know if all kinds of pick up coils generate low voltage to excite the CDI? My engine is an RM 125 and 92, but it did not generate something voltage i think have a problem from my pick up coil, what do you think ?

[@kan815k]

Hi, I have seen someone put capacitor on coil side to make plasma effect on spark plug. Connected to earth and HT cable side. Do you have an explanation of this purpose.

[@AllAmericanFiveRadio]

What is HT?

[@padraiggalvin2807]

@@AllAmericanFiveRadio High tension

[@kapilsethi8054]

Can we use hall sensor in place of pulse rotor.? If yes what changes will require

[@AllAmericanFiveRadio]

It’s always a good idea to stay with the original parts.

[@kapilsethi8054]

@@AllAmericanFiveRadio yes you are right 👍🏻

[@aNuthaRedneck]

I'm struggling to understand how to diagnose exactly where problems occur in a CDI circuit. If anything goes wrong in the circuit there will probably be no spark from the coil??? If there is no current to the coil but the stator is putting out how can I determine if the problem is in the trigger, SCR, or diode, or one of the connecting wires? I have my ideas but want to know how others do it...

[@AllAmericanFiveRadio]

aNuthaRedneck To troubleshoot any circuit you must first understand how each component functions. Once you have this understanding then you can test each component to see if it is functioning properly. Some of the major components in this circuit are the SCR, diodes, and transformer. You can do a local search on my channel and I have made several videos of how these components function.

[@aNuthaRedneck]

Thanks... this can be very important in correctly diagnosing outboard motor issues.