Inside a cheap CDI Capacitive Discharge Ignition module - with schematic
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- čas přidán 23. 08. 2024
- Another economically made module from the wiring loom of a Chinese quad ATV or scooter.
This module interfaces between the magneto/alternator and the ignition coil to provide high current pulses in sync with the engine.
The use of a high voltage winding on the alternator/magneto is to store as much energy in the 1uF capacitor as possible for dumping through the ignition coil in pulses to induce a high voltage spark.
It's a very simple circuit, but this one has some odd quirks compared to others.
Is the input RC arrangement to provide a speed dependent timing variation for the spark?
Is it normal to short circuit the high voltage winding of the alternator on each alternate half wave?
Anyone had a shock from the appropriately named "kill circuit" on the keyswitch or engine switch?
Let me know what you think in the comments.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
www.bigclive.co...
This also keeps the channel independent of CZcams's advertising algorithms allowing it to be a bit more dangerous and naughty. - Věda a technologie
Clive, I found your channel through AvE and I’m glad I did. I appreciate not only the clear description of what’s going on but also of the weirdness of the circuit.
Here to find out how those angry pixies chooch huh :)
the extra triggering circuit is to advance the timing at higher RPM , the first capacitor charges up more at higher rpm causing it to fire a few degrees before top dead center, this causes the fuel mix to fully ignite earlier so when it passes TDI it has the most pressure to push the piston back down, giving the engine more power.
You can see this clearly with a timing light when you point it at the flywheel, you will see the timing mark move backwards gradually at higher RPM.
The CDI you took apart has automatic timing advance, the second diagram you showed has none and wouldn't be as good for high rpm engines.
In fact, simple CDI's like these don't actually advance at high rpms, they just retard less. The sense coil is before TDC. Also typical bike CDI's will have a very significant low rpm retard so the bike is easier to kickstart, the timing will jump above ~2000 rpms, which is clearly visible with a timing light, it is a very sudden change. I don't know exactly how this is achieved.
@Nicolás Rodriguez depends, some flywheels generators have a simple round timing bump , some have a long raised strip, its important that the correct CDI box be used to match the timing mark on the flywheel, if the timing isn't correct , you would either get a lot of sound but no power or melt the piston with overheating.
iv seen the timing belt marker move when the engine is revved under that light flashing like a strobe. learning this stuff later in life is crazy sometimes getting the answers you ask in you head years ago on 1st seeing something. thank you for that bit of info MrPlytiger!!!
The second capacitor in series with the gate circuit is a differentiator i.e. it's output will be dependent on the rate of change of the input which also provides an advance function.
Thank you for that. I was wondering about the discharge path of the 3u3 cap and had assumed a tracing error. I'd not considered spark timing.
My most memorable ignition coil zap was when I touched a defective coil wire while standing lightly against a car. The charge entered my hand and exited to the fender via my lightning rod. I'll never forget that one.
Chad Thundercock
There's something about this sand business that really gets my goat.
Several of my customers and myself have received the shock you suspect when connections fail. Sometimes at the metal handlebars when the earth connection is lost. Sometimes at a metal key switch. Precisely as you predict rather a surprise, also happens on mowers and such with magneto spark engines.
Had it with the lawnmower, very irritating
The man, the myth, the legend. Funny running into you on CZcams Jon! -Vince Jr
@@vincepale you are also the man, the myth, the legend!
After years lurking, you clearly, definitely, without questions, deserve a sub clive!
Seriously!!!!👍
The input RC arrangement is in fact for timing. In fact, simple CDI's like these don't actually advance at high rpms, they just retard less. The sense coil is way before TDC. Also typical bike CDI's will have a very significant low rpm retard so the bike is easier to kickstart, the timing will jump above ~2000 rpms, which is clearly visible with a timing light, it is a very sudden change. I don't know exactly how this is achieved.
The diode short circuiting is to avoid high reverse voltage I understand. Open circuit voltage can go high enough to damage the coil, wires or circuitry. The energy isn't much and it isn't a problem to just short it. Keep in mind the rotor has many poles (there are different arrangements, also there can be more than one magneto coil) so the capacitor actually charges in a couple of pulses
Completely agree will all the statements!
I was just about to say the same thing, but you beat me to it!
Could a capacitor be wired in to retard the spark to help starting say on he signal wire?
Thank you very much for this video. You have answered the great questions of my childhood. Back in the 80's I had a motorcycle that had a bad CDI unit and the replacement part was beyond affordable for a teenager without a job, so I ended up selling the bike... If I would have understood how they worked I could have fixed it myself.... knowing this now brings relief to my mind! I always hated potted circuits because I could never get them apart without destroying them..... Your videos are awesome, thank you for doing these. I am learning allot!
If you haven't had a belt off an ignition coil you've never lived!
or a TV Flyback circuit.
The worst shock I've ever had was from the HF start on a tig welder.
I remember my dad and I were changing the spark plugs on the bikes, I was testing for spark for some reason so I touched the spark plug to the chassis with my thumb still on the metal part of the spark plug, when I went to turn the engine over I got a big jolt through my hand! We were both in stitches after that!
@DARK APPARITION Yeah, I learned not to touch the metal part! I am super careful now but I know it's going to happen again! These things happen lol
@DARK APPARITION I have never had a shock from a flyback before, I dismantled my old iMac G3 to clean it and put a led strip inside it, I was so scared about getting a shock from the tube I unplugged it for about a week!
A modern ignition coil is way worse than any measly flyback in a TV!!
A flyback makes a nice soft little tiny arc meanwhile a modern ignition coil will jump over a 1-in gap with a thick nasty spark!
And yeah I've also been bitten by HF Tig That's no fun either!
WOW another video form the loom that just keeps giving. 👍👍
Using the "ramp" on the sense coil would tend to give some ignition advance at higher revs so quite clever
Running a higher primary voltage allows them to have a lower primary current and less loss over their thin wiring loom.
Shunting a couple hundred volts through the operator isn't a concern for chinese scooter makers lol. Maybe that's why they call it Bang good. Some products go bang, sometimes you go bang, but you paid 2 dollars so it's all good.
You know it's not just the Chinee stuff, I used to have a Yamaha motor bike that was notorious for giving a random, unexpected jolt from the kill switch. And by random I mean while riding along not pushing the kill switch.
Ive rode many of these and seen many videos about them. Not seen ANY reports of anyone getting shocked by one ever. My god my carpet exposes me to several kilovolts in the winter. Must be made in china...
Now you should open chinese CDI with "adjustable ignition timing".
that arrangement is probably to create a delay to change the ignition timing with the RPM.
modern small engines have the advance circuit built into the coils themselves so they don't need points. it's also a good way to design in a failure point into all crappy lawnmower engines.
Good point, it would be interesting to see the delay values on a scope at different hz! You could even swap out components to alter your advance curve
You are amazing.
For years I have been looking for this to design my own fancy imitation cheap imitation cdi
I have also wanted to make my own circuit but the chinese cdi units are so cheap that I just spend the few bucks and buy them lol
The secret is sand.
Yeah but I ain't rich like that.
And well R.C. that's a good thing since I wanted to produce a few dirt cheap for testing.
I want one that's got it all though. Now I have to keep switching cdis.
That's why I wanted to build my own with several settings, a simple moped ecu one might say. At first I wanted to build a switchboard but with all the wires it thought it would be to relay-able so I tried to find schematics so I could simplify the wiring but I couldn't find anything clearly close enough to pick from. It was a few years ago and since then, after getting more experienced with electronics, I decided to build my own one day because whichever type seemed most suited could probably fit several selectable modes in one device.
And recently I was thinking about a mounting bracket for my cdi instead of the rubber strap but now this is here and finally some fitting schematics too since this is my hi rev unit's copy.
Definitely interesting as I'm about to tackle a 1953/1955 farm all tractor. Originally 6v my dad and I switched it over to 12v years ago. I'm about to rewire the whole tractor. With my unit 210e at hand, newly purchased. Cheers.
That diode to ground across the HV coil is simply to load the coil as it goes negative, this prevents flashover damage to the coil. The R/C combo in the gate circuit is to average the trigger pulses to make sure the SCR triggers only at the peak of the trigger pulse at all RPMs, to keep the ignition timing correct.. These CDI designs are normally fitted to 2 stroke engines that have fixed ignition timing.
I think the diode across the winding is to clamp the negative excursion as the coil would produce a very high negative voltage at high revs and damage the rectifier diode or arc across the kill switch.
The mystery diode is for energy recovery from whatever energy is left over after the spark event that was stored in the coil's inductance. It catches it on the reverse voltage swing, thus re-charging the capacitor to a certain degree. Which is actually a better design than the simpler circuit you showed because it also provides protection without wasting energy. Sand as a potting material? Who knew! Thanks for the video. I am surprised the discharge capacitor is that large. I would have thought no more than about 0.4µF
I never thought that trying to fix my bike would lead me to a Big Clive video, what a comfortably familiar space! 😆
So interesting thing, my bike uses a very similar looking device, but it does not utilize the killswitch lead in the middle. Instead, the timing signal coming from the stator is wired through the ignition switch to the sense input on the CDI, and the killswitch grounds out the timing signal via another lead between there. I think that older models of my bike, as well as the version of the same bike for the European market, do utilize the kill pin, and have the timing signal directly wired from the pickup coil.
Piaggio is a very famous and old italian brand. They've made the iconic Vespa, Ape and Ciao scooters, (just to list 3 of the most famous products). 🛵🛵🛵
i use to have a chinese scooter. It was so cheap to get parts and taught me a tonne in the process of fixing it, which was at least once a week. My one even started tearing where the shock absorber bracket connects to the super thin steel tube frame.
Would be keen on seeing you bench supply and o'scope test this CDI circuit to reveal the mystery cap is a design to vary the timing based on rpm pulses.
Peace and much love.
The weird circuitry on the gate of the thyristor is usually used to prevent transistors from saturating and increase switching speed. It gives a bit more initial current and then less to prevent saturation. It's frequency dependant though.
The additional circuitry on the pick-up (trigger) circuit is to provide filtering and manipulate the ignition advance (fire point relative to piston/crank position) through the rev range.
High performance two-strokes generally need less advance on high rpm, so they can dump the ignition heat on the pipe to protect the engine and make more power.
Low performance two strokes and four-strokes need increased advance in high rpm's to compensate the lack of pumping and combustion efficiency.
The CDI circuit and the AC magneto must live in perfet harmony, otherwise low energy misfire or low engine performance may happen. This is hard to get right.
Some CDI's have weird trigger circuit due to the way the AC magneto works. There are a lot of types ranging from exterior pick-up (1 pulse per revolution) to interior pick-up making 2 pulses per revolution (one is wasted) and interior pick-up with weird arrangements between the HV coil and the position sensor.
Some older designs, like the spanish Motoplat found in many mopeds, use some electronic components on the stator itself. That's why you see so many different trigger arrangements.
The cable color scheme and CDI type is clearly Honda clone, as used on smaller motorcycles (both 2 and 4 strokes).
I'd buy a t-shirt that reads, "Well worth taking to bits."
So Clive we are all waiting for your first "Will It Start" video featuring a quad 4 engine and your recently purchased wiring harness.
I am glad all my cars have Kettering ignition. Simple, and easy to fix if a problem crops up.
Interesting indeed!
I've been working on building a microcontroller powered replacement for a two wire CDI (no sense line; it just uses the zero crossing of the HV line to trigger). Should be fun!
Interesting series of videos, Clive . :)
Would it be interesting for you to set up a test rig with connection(s) to an oscilloscope to see exactly what's happening with those odd components?
To double the spark energy, remove the single diode used to charge the capacitor and replace with a full-wave bridge wired across the stator and remove the diode that is shunting each half cycle. With double the energy now available to charge the cap, the cap value can be doubled. The stronger spark will improve combustion and thus power and fuel economy.
There is also another module style sold as points replacement for magneto plus mechanical points.
In these the trigger sense is off the high voltage feed from the magneto. The original points short the coil and magneto to suddenly collapse the current.
The replacement triggerd the short circuiting thyristor as the voltage just starts to drop with a capacitor circuit and a PNP transistor.
The wire colout codes used on cars correspond. Black switched ignition, red permanent battery, brown earth. My 1973 VW camper uses that scheme.
"Filled with sand". I got a flashback to the cheapy cheap PC ATX PSUs of mid 2000's where they would put a piece of cement in the PSU to add weight to simulate "Much quality! Best copper! Cool alu!".... then they added 200 extra fake watts to specification. The cement blob was disguised as a filter/ballast for power factor correction.
I had a digital camera in the early 00's that had a quite large lead weight inside for that very reason. I've forgotten the brand now, but they were quite popular with the RC aircraft set at the time because they were so light once you removed the ballast.
I much prefer this type of vid from you Clive, far more interesting and enjoyable.
SCR/TRIAC's can withstand substantially more current on their trigger lead if it is duration limited, and a higher current pulse ensures consistent triggering in the face of device parametric variation due to temperature and manufacturing. The capacitor in series with the trigger lead limits the amount of energy delivered in each trigger pulse, thereby allowing for a higher peak current.
Rather than wasting half of the magnetic energy being produced, why not just connect the stator coil to a full wave bridge so that all power pulses can be used to charge the capacitor? It would then be possible to double the size of the discharge capacitor since twice the charging power would be produced per engine revolution. Having 2X better spark would make it easier to start the bike, allow for more complete combustion, improve performance, fuel economy, and reduce emissions. This would also eliminate the need for the quench diode needed to dissipate the negative stator pulses.
Very interesting. We've sold hundreds of these 12v CDI boxes for Honda CRF50 style engines from 70 to 160cc engines.
Tear down a 7r sharpy beam (off brand) I’d find that so interesting, I remember you did the little led one
Makes me wish I depotted the ignition on my outboard instead of replacing it. So much voodoo info out there on 70s era cdi this is.a pretty simple system. FYI a 70s era four cylinder Evinrude has about 450 volts out of the megneto. That hurts when it bites you.
I watch a lot of videos and you do a great job of explaining and make it easier to understand. The only thing I would hope you can do is when you draw out a schematic, that you write what it is. I do screen shots, so I can experiment with them later. But by the time I get to them, I forgot what what it was for. Thank you if you could do this.
The spark is generated with the collapse of the magnet field in the coil primary winding. The diode across the primary coil in the second schematic will pull coil to ground rapidly, enhancing the spark at the plug.
That's as I always understood, that it's the collapse of the voltage in the primary windings that induces voltage in the secondaries to produce a spark. The coil is fed a live and the module is on the "earth" side to break the circuit in response to a pulse from the sense trigger. This looks like a single cylinder either motorcycle or plant power, not sure if anything works differently on some small engine stuff.
You both confuse CDI with the classic ignition system.
@@Plons0Nard diference betveen clasic and cdi is that classic use 12V and high power mosfets to create spark while cdi uses high voltage capacitor and therefore doeas not need a lerge amount of current (CDI capacitor discharge ingnition)
TCI/point do rely on charge/collapse the external coil, the CDI works pretty much like a simple transformer. Both coils are not compatible.
BTW, the CDI system have a faster spark build up, and usually shorter, than TCI (12v) or points, make them very actractive for determined engine types.
Honda have been using black as switched live for years, green for earth also it needs a minimum of 8mm spark to fire a gap of about
.7mm under compression with fuel mix.
well explained. input capacitor filtering to allow only trigger signal. resistor devider to adjust igbt gate volt spec. Also may be freewheel diode can have small series resitance to limit max current of freewheel diode
Thanks Sir for reverses engnireenig.
Love from Pakistan.
The Chinese construction industry might not have enough sand for making concrete, eventually...
concrete needs "sharp" sand to be strong, this can work with desert sand whose grains are nicely rounded off...
On the Piaggio schematics the diode that is bridging the primary winding of the ignition coil isn’t for protecting the thyristor from back EMF but for fully discharging the stored energy into the spark gap . So this diode make the spark much powerful and longer .
I always just assumed CDI systems needed a honking-great cap, but of course you don't need much energy to arc across a 1mm gap.
It compensates for the capacitor size with the voltage.
it needs about 8mm spark in free air to fire .7 mm under compression with fuel mix.
You do need a fair amount of voltage/power when the atmosphere is something like 7-8% gasoline and compressed to several atmospheres of pressure (i.e. far higher insulation resistance than air). That's why when testing spark on an engine you're looking for a fat white spark on the plug or an arc a centimeter or so long if you're daring enough to stab a screwdriver in the boot and hold the handle.
I believe the 10uF capacitor in parallel with 5.6k resistor is most likely an RC Filter for high frequency noise coming from the Magneto/alternator.
Simply excellent! Thank you.
When fixing the older pre-CDI contact-breaker type ignitions, almost any replacement capacitor would do, as long as it was rated for mains voltage. We would recognise a faulty ignition by a weak spark at the spark plug. We'd first judge the colour of the spark, should be blue, and the distance the spark could jump from the lead to the engine. Should be about 10mm or more. This to determine if there was an ignition problem at all (other than timing). Next we'd check if there was any sparking between the contact breakers. A breaker ignition with a good capacitor will have next to no sparking between the contact breakers. On an ignition with a bad cap, the breakers will spark at every revolution.
the gate circuits determine the engine timing based on rpm
These chinese cdi units come in two types. One gets it's power through a magnet on the flywheel passing a magneto coil. A battery is not required for the ignition system to work. This allows kick starting with a completely dead battery or no battery depending on what the engine is being used for. The second cdi type uses 12vdc for power. This one is very easy to adapt to just about anything to replace an ignition module that is no longer available for both vintage engine's and engine's where the original ignition module would be very expensive to replace with an oem module. All timing sensors are the same so the 12 volt module is easy to hook up to the original flywheel sensor but you may need to move it's position depending on how the original ignition module worked. If it was an early cdi type you may not need to do anything. If it's a modern microprocessor type you will most likely need to move the sensor because it sense's when the flywheel passes top dead center. For the Chinese cdi units the sensor needs to sense maximum advance degrees. Those chinese cdi units retard timing instead of advancing it. At idle the unit is fully retarding timing but at higher engine rpm the unit stops retarding the the timing so it's firing the spark plug at the static timed fully advanced point.
The second diode is part of a classic voltage doubler circuit...
Hi Clive.. The ignition switch is based on Honda's wiring colours.. so red is battery and black is live after the the main switch..
as a bike mechanic, yes, i've had shocks from bike frames, killswitches and ignition locks... it happens
I took mine apart too, It was an older model and it even had some potenciometers in it. Engine run very well till, I got a short from too much water:D
Chuckled at the 'Kill switch chat', my 1st motor bike a Triumph Cub in the 70's had been 'refurbed' by the seller and had put a horn button on the bars as an extra kill switch, but unknown to me had earthed the coil HT OUTPUT, like some lawn mowers and the metal strip onto the spark plug. And yes the 1st time I found out was with no gloves on but I got a good deal as he told me 'it cuts out when it rains'. Wonder why.. :-)
Clive, we'd love it if you soaked and reverse-engineered a CB400N hitachi CDI. Y'know, the TIA01-20 :D
The ignition coil from a car can be very useful for high voltage experiments ⚡⚡⚡
Made a self oscillating circuit for one. It fires 5-10k times per second, and the arc is hot enough to melt solder and light a candle. You can check out the video on my channel.
Yes, you can indeed get a shock from the kill switch wire, seen it happen quite a few times on small boat outboard motors, with varying degrees of amusement.
Agreed- much funnier when it happens to someone else
Could you do a teardown of one of those cup coolers that have a Peltier inside? The ones meant to sit on your desk.
i feel even naughtier, only 630 views!!! and i am SERIOUSLY interested in these cdi modules, especially on the happytime engines, never opened 1 up
yes, we get to see this unlisted video from a link Big Clive put in comments from an video of the motorbike loom teardown, us non patreon peasants have been spoilt. thanks Clive.
i think i am going to watch the video again because i forget the solvent clive used and then try to de-pot a happytime cdi, thanks again BCDC :)
Great stuff Clive, thanks!
Nice
Good infos and nice video reverse engineering is awesome
very nice, thank you a lot.
Tnk u so much for this video i learned alot
Im guessing they include the reverse diode in the first module so the magneto voltage just doesn't sail off into the sunset. There's no real harm as it will essentially be like the catch diode on a relay. It will simply allow current to flow and then decay out from the resistance of the coil and wiring.
Just guessing the reason the piaggio design is simpler is it lacks somewhat of a timing curve that the other circuit has. The one cdi is for a 4 cycle engine as the piaggio is for a 2 cycle. Again, I am just guessing
Odd thing about the CDI system is it works completely backwards to a conventional ignition system. Typically for most car ignitions, the coil is driven just like it would be in a flyback power supply. There is a dwell time (equivalent to duty cycle) that allows the current to ramp up until the coil is nearly saturated, and then the transistor switch snaps off, resulting in a flyback pulse that fires the spark plug.
I'm trying to get my head around the CDI vs conventional thing.
" that allows the current to ramp up until the coil is nearly saturated, and then the transistor switch snaps off, resulting in a flyback pulse that fires the spark plug."
So spark occurs when mag field collapses ?
@@Boraxo Yes, spark occurs when the field collapses.
But of note, in a conventional car ignition system the coil is switched with "points" in the distributor instead of transistors.
Research field collapse magneto and field buildup magneto.
It's like one of those cheap zapping fly swatters but only potted. Looks like this would make a hell of a bug zapper.
Just hook the sense up to an NE555 PWM circut
Piaggio is a model of scooter. It's where the Faggio from GTA gets it's somewhat appropriate name.
Most large cc Japanese bikes these days have what they call 'COPS' (coil over plugs) the coil is built into the plug cap, makes easier hot starting & more efficient fuel economy cos they create far more spark impulses for igniting the fuel & the bike will not need half so much cranking to start
Some times they have a rev limiter built in on the uk ones they cut one of the wires to by pass may be the sensor one.
Maybe the little "tank circuit" between the sense and trigger acts like a variable time delay that varies with RPM. Anything that adds a little more spark advance, too a point, as RPM increases would add performance to the motor. As RPM goes up, the incoming sense pulse should be ramping faster and faster as it narrows. I'd like to see the circuit on a scope while being stimulated at different frequencies from the sense line, to see if anything happens to the timing of the trigger as frequency input changes.
I'd like to know how to have a capacitor wired in to retard the spark to make starting easier,
Yup, the lead from the ignition stator of most bikes/quads will give ya a little razz, it's quite low current so it doesn't hurt really bad though.
I believe the extra unexplained 10uf capacitor is possibly for timing advance. Not all of the standard black box Chinese have timing advance though one. I bought one off Amazon and did not have timing advance while the one that came with my pitbike did, while still looking the exact same on the outside
Piaggio is an Italian company, creators of the Vespa, I didn't know they made their own igintion systems, Classic style Vespa had Femsatronic ignition, later they had Ignition systems manufactured by Ducati.
I'd have thought the electronic systems on more modern Piaggio vehicles might be manufactured by Marelli.
I would love to see an dc cdi depotted
Those have a boost converter to get the 12v to a 200v to charge the capacitor
Likely based on the flash circuit from an 1970's camera I bet
Indeed very enjoyable indeed👌
can confirm in rainy weather being shocked by my cheap ebay bicycle engine kit kill switch haha
That circuit remembers me a lot to a dimmer circuit. I wonder if they copied the thyristor gate control circuit from from a dimmer design. That could explain the strange arrangement of resistors and capacitors.
The world is running out of sand ...
... because it's all been potted into cheap Chinese electronics.
The worst bit is we are actually running out of sand. More than a billion tonnes a year used for concrete alone.
*China is running out of sand
Ftfy 😉
I wonder if it's really sand or is it some fine ground glass or other waste product (no better way to dispose of e-waste than ship it out worldwide in junk products) :))
nothing would surprise me anymore.
@@throttlebottle5906 glass is higher value than sand and can be used to replace sand in construction if you grind it correctly. They are both mostly silicon oxide (construction sand is anyway).
They are pumping a LOT of sand back into the ground in the USA for fracking.
its quite simple triggering i made one myself first you have diode for just positive then you have capacitor not too big not to small just perfect to make voltage smooth them you have two resistors as you didnot noticed they limit the input current to rsc as at hast pulses 10uF capacitor have small Rx (thyristors dont need high voltage to turn on just about 0.7V they are triggerd by current spike thats what 10uF cap does) 5K6 is just for discharging and 3K9 just prevent thirystor to stay on for too long
Would you do a tear down of a Chinese diesel air heater please
I enjoyed that! what's the ignition coil like inside? is it optimised for cdi?
Back when I was doing automotive I recall black as switched live being quite common. No idea why they chose that, but some Ford wiring looms (possibly Cosworths? Was many years ago!) are one that springs to mind as having "live blacks"
Ford North America still used live black well into the 80's/90's. But the real winner in wiring is JCB in my opinion, EVERY wire is white. the only ID being an inked number on the insulation.
@@alexb.1320 That's actually pretty common in industrial and heavy equipment.
I'd guess the 3u3 is to store a bias voltage to get the thyristor close to trigger V and the bypass cap ensures sufficient gate current ,limited by the pair of 680rs
Could a jewel-thief circuit be incorporated into the collapsing EMF to provide a trickle charge back to the battery???
Just curious, because I've seen this circuit being used in HHO generation... And anything you provide back to the battery increases the efficiency
piaggio is very common here in tunisia ,,they are known to be not the most reliable but the cheapest that will get the job done ...but its almost all small motorcycles and its also italien
How about pulling a DC CDI to bits? Be interested to see the boost circuit
Hi Clive, I'm wondering if, in the first circuit scenario, the resistor- capacitor in parallel could have anything to do with ignition timing? I see now that I read further that someone has already made a comment to this effect. The actual change in ignition timing could be calculated so to allow for different engine applications. In a mechanical magneto an "impulse" coupling is typically employed to provide a retarded timing at cranking and as engine starts and runs, the impulse mechanism is locked out and the timing advances to a predetermined setting.
The sand is a heat sink for the triac often it's ground ceramic material
Buena enseñanza.
¿Logró conseguir el esquemático de un CDI para moto 150cc alimentado a Batería?
Para no usar la bobina de arranque del estator, sino usar como alimentación la batería.
Lo lamento. No tengo un esquema para eso.
Shunting a magneto with a diode is not unusual it limits the peak reverse voltage at high revs and it causes negligible engine load due the magneto leakage inductance which a reactive load. I have played with these on a variable speed test stand and found the reverse voltage will increase in proportion to the revs if left unchecked the forward voltage is limited by the load presented by the capacitor and the leakage inductance of the magneto. The simplicity of the circuit is typical of 1970's motorcycle CDI's. Inert fillers in the epoxy potting are to reduce both the cost and the peak exotherm during curing.
is the "complex" part there to adjust the time it triggers? it should not have the same trigger point at different RPM's. the higher the RPM the earlier it should trigger.
I get your point but the advance really depends on the engine itself. High performance two strokes need way less adavnce in high rpm's.
Other things of note, Thyristor = SCR. Make sure you know that. it is a gated Diode
There can possibly be atleast 4 different cdi circuit types. One for two stroke engines, another for four stroke. Then there is ac systems and DC systems, the DC system requires a battery to start the engine, then there is the ac system that can be kick started with out a battery, it gets its power from the generator/alternator system on the engine. Then there can possibly be atleast two more, with adjustable timing for easy starting, or whatever i couldn't tell mine did anything. I didn't have a timing light. Then they would have on for each 2stroke and 4 stroke , im no 2 stroke guy, but hear a two stroke required a different timing curve . Required less timing at high rpm where 4,strokes want advance at high RPM.. a two stroke can easily burn a piston at high rpm i guess the timing helps prevent it. A two stroke is busy at ig rpm, it need more time at high RPM by retarding the timing. Just from bits i hear, besides a chainaw and weed eater i dont do 2T often.
Possible timing advance at higher rpms?
Hey Clive
If I grab my ignition leads when the bikes running should I feel the zaps or not
Do I have a grounding issues
Also it's kind of fun to hold em
Reminds me of this game at Chucky Cheeses were it shocked you and the longer you held on the more tickets you got