AC-CDI v9


Features

  • AC-CDI
  • For ONE or TWO* cylinders
  • Microprocessor control unit
  • Wireless and easy programming and the fly via smartphone or laptop
  • Compatible Android, Iphone, Windows, Linux smartphones and/or PC
  • Programming security:
    • Only possible when engine is stopped.
    • Only possible when ignition key is ON.
  • One programmable ignition curve
  • Rev from 200 to 20,000 RPM
  • Adjustable timing in 10 steps from 1000 to 10,000RPM
  • Adjustable timing at very low RPM (~250RPM)
  • Soft rev limiter.
  • 1 input for a inductive pickup
  • Selectable pickup polarity (2 types)
  • 1 output for a capacitive coil type
  • Non volatile configuration
  • Tachometer output
  • Kill switch
  • Power supply voltage DC 8 to 16 volts
  • Current consumption: 60 to 100mA
  • Protected against reverse supply voltage
  • Dimensions: 80|106 x 64 x 25mm (3.15×2.52×0.98inch)
  • Strong grey extruded Aluminum box
  • Made in France


Cylinders:

Mono-cylinder:
If there is one separate pickup
=> This AC-CDI works.
If there are 2 separate pickups (one for low RPM and one for High RPM)
=> This AC-CDI works.
If there is no separate pickup and the timing is done by using the High Voltage of the stator
=> This AC-CDI will not works
If the engine works with missing teeth
=> This AC-CDI will not works

* Twin-cylinders:
If the engine works with WASTED spark and if there is ONE twin coil.
=> This AC-CDI should works.

If the twin engine doesn’t support wasted spark:
=> This AC-CDI will not work

Remember that ignition coils are different from TCI to CDI system
– CDI coils have low inductance and impedance around 0.5-0.8ohm
– TCI coils have higher inductance and impedance around 1-3ohm

Remember there are AC-CDI and DC-CDI…


Pickup:

– 1 input for inductive pickup with 1 signal per crank rev.
or for 1 inductive pickup with separate output for low and high rpm (XT600)
– Pickup must give 2 to 30Vac
Points, reluctors, Hall sensor, optical sensors can be used as long as they give only 1 pulse per revolution.
– CDI is not compatible with multi-pulses pickup or missing tooth wheel.

– input for low pickup if any
– if the pickup is NEG/POS (ie suzuki) jumper JP2 can be close to help cranking.


Rev Limiter:

There is no “Hard rev limiter” that stop all sparks above a given RPM
but you can drop the timing back far at high end so the engine cannot rev more.


Wiring:


WIFI range:

5 meters distance from the CDI (compared to a regular ISP box at same distance):

10 meters distance from the CDI :


Troubleshoot with LEDs:

In default CDI mode, with KILL SWitch not connected to GROUND:
Blue led blink 2 times, Red led blink 3 times then both led are OFF: mode_CDI
Slow motion: mode_CDI_slowmo

In Access Point mode for wifi programming, when Kill switch is connected to GROUND prior to turn the master key ON:
Blue led blink 1 time, Red led blink 3 times then both led are ON.

A buzzer sound after 5 seconds meaning the CDI is ready to be programmed : mode_AP
Slow motion: mode_AP_slowmo


WIRELESS Setup:

To proceed to the initial setup

  1. First connect the wiring of the AC-CDI
  2. Turn the Kill SW on
  3. Next turn the master key on (+12Vdc)
  4. After earing the bip sound from the CDI, seek for the “transmic_cdi” wifi network on your smartphone.
  5. Connect to the Wifi Access Point (no password is needed)
  6. Open up a regular browser. Point it to http://transmic.fr or http://194.168.4.1
  7. You get this home page:

  8. Clic on the configuration button and follow this video: Wireless Setup
  9. Finally turn the Kill SW and the master key off.

BOX:


PCB populated:

29 thoughts on “AC-CDI v9”

    1. Version v9.0.0 is designed for 1 cylinder.

      It should work on a Twin-cylinders if the engine works with WASTED spark and if there is ONLY ONE twin coil.

      ie: It works on BMW as they are opposed twin/4 strokes, and needs only one spark every 360°, the very same as a single cylinder/2 strokes.
      Their twin coil has 2 outputs and fires the 2 sparkplug at the same time.
      (One spark is wasted as one cylinder is on its exhaust stroke.)
      See left part of this animation.

  1. As you mention the ignition can handle wasted spark, I supposed it then can work for a three-cylinder engine with wasted spark and three ignition coils firing in paralell, that gives one real spark for ignition + two wasted sparks per revolution for each cylinder.
    For example a three-cylinder engine that revs 8000 rpm, the ignition need to produce 3×8000= 24 000 sparks/min, or 400 Hz.
    What is the maximum sparks/min the v9 ignition can produce?

    1. You are right. It could theoricaly work… but there are 2 limitations: hardware and software
      Hardware :
      The CDI has one output meaning that it can drive:
      – one coil: fit 1 cyl
      – one twin-coil: fit 2 cyl
      – 2 coils in parallel: fit 2 cyl
      – a distributor to fit 4-8 cyl
      if you drive 3 coils in parallel , their low impedance will be divided by 3 and can destroy the output SCR inside the CDI
      It also mean there are wasted spark during intake and exhaust strokes inside the 2 others cyl.

      Software:
      Without wasted sparks:
      Number of sparks = ( RPM x cylinders ) / 2
      ex: 3000rpm on twin cylinders: 3000 x 4 /2 = 6000 sparks / minute = 6000 /60 = 100Hz

      With wasted sparks:
      number of sparks = ( RPM x cylinders )
      ex: 3000rpm on twin cylinders: 3000 x 4 = 12000 sparks / minute = 12000 /60 = 200Hz

      AC-CDI v9.0.0 can reach 400Hz but the RPM range that is adjustable is 500 to 10000RPM (then 250 to 5000 on a twin)

  2. Sorry I was unclear about my example about the three cylinder engine!
    I was referring to a two-stroke engine, that ignite the fuel every revolution. My intention was to use the CDI on a two-stroke engine.
    Ok, so essential you are saying that the ignition can handle 400 Hz, but the possible problem with three paralell coils would be the low resulting impedance from them, affecting the SCR!
    – Would it work then if the three coils are in series instead (at 400 Hz), that means adding 3 times impedance, compared to a single coil impedance?
    – If I understand you right the adjustable part of the curve is from 250-5000 rpm if useing the CDI on a two-stroke (without wasted spark). But it will give sparks up to 10000 rpm for a single cylinder two-stroke engine, and sparks up to 20000 rpm for a single four-stroke engine.
    – Is it only a programming issue that make the max limit to 5000 rpm for one spark on every engine revolution, or is it the processor speed that are the limitation?
    – Do you have any possibility to make an alternative PIC-programming for a two-stroke application?

    1. To drive 3 coils your need a CDI with 3 outputs. That’s it!
      Otherwise serial or parallel are just compromises…
      Parallel (high current) is a threat for the SCR depending on its characteristics and need a bigger cap
      Serial (lower current but lower tension) is poorer performances.

      I don’t have experience with 2 stroke as there are rare.
      As I understand it, RPM is divided by 2 for a twin 4 strokes (useful spark each 2 crank rotations) but is not for a twin 2 strokes (useful spark each 1 crank rotation) so this CDI “should” perf the same (adjust until 10,000 and capable of 20,000)

      If your current CDI works, why don’t you check that on yours?
      Plug a scope on each sparkplug and on the main pickup and do the math.

      it’s software limitation for the most part. Processor speed only limit the accuracy at high RPM
      This coming AC-CDI is intend to be sold only 😉

    1. Thanks for your interest !
      It’s plan to be available this month March2018.
      At the same time I change the whole site look.
      BR

    1. Please check the bike manual.
      Aprilia 122 is a 2strokes Rotax engine with AC-CDI and 1 trigger coil.
      ignition view
      So it should work.
      If not, send it me back during the 30days warranty.
      (warranty does not cover the port fees)

  3. @Headlee: I can’t answer your email (wrong addr).

    According to Google Beta 300RR is a 2strokes single cylinder with AC-CDI
    Well …“Kokusan AC-CDI” doesn’t help a lot, like “Dell laptop” don’t give informations about the PC.

    This AC-CDI v9 can be used as replacement on any single cylinder equipped with AC-CDI that has a separate pickup giving ONE pulse per rotation.
    The AC-CDI v9 must be powered by a 12volts battery

    Does your bike fit this requirements?
    Single cylinder: OK
    AC-CDI: OK
    External 12v battery: ?
    External pickup: ?

    Look at the electrical scheme in your engine manual to see if the CDI use a separate pickup.
    In 90% of the case, it does.

    Your AC-CDI must have at least 5 wires:
    GND
    +12v
    charging coil
    Pickup coil
    kill switch

    I think it should work, If not send it me back before 3months for a 79€ refund via your Paypal address.

    AC-CDI v9 has only one map.
    The unique advance curve can be tuned wireless.
    No dedicated app is needed thanks to the usage of any regular browser. (html page)

    Th

  4. Hi Thierry,
    Yamaha SRX-600 1985-1987 is very similar to Yamaha XT600 etc –
    brown wire and red wire for ignition energy
    white-red, white-green and green for pick-up
    according to the workshop manual, ignition timing is 12 degrees from 0 to 2000rpm, ramps to 34 degrees at 4000rpm and higher
    No electric start on SRX600….

    Your AC-CDI V9 uses only the first pick-up signal, right?
    And there’s no way of knowing if the engine is at TDC-firing or TDC non-firing stroke, so you always fire a spark at both firing point and at end-of-exhaust-start-of-intake…. right?

    From https://transmic.net/2016/07/14/yamaha/, if I understand right, I think that the standard CDI works like this –
    at low engine speed, ignition is fired on the second (negative) pick-up
    there is another bit of circuitry (analogue frequency-to-voltage) that creates a discharge of the capacitor, delayed after the first (positive) trigger….
    below around 2000rpm, this delayed discharge happens after the second (negative) pick-up has already fired the spark, so nothing happens
    as engine speed rises, the delay gets shorter… above around 2000rpm, this discharge happens before the second (negative) pick-up, so it fires the spark. When the second (negative) pick-up “fires”, it does nothing because the capacitor is already discharged
    above about 4000rpm, the analogue delay is effectively zero, so the spark fires on the first (positive) pick-up

    Is this the correct understanding?

    So how does the AC-CDI V9 time the sparks?
    Obviously, you use the time between first pick-up pulses to calculate the engine speed…. and then look up from the programmed graph what the spark timing should be…
    So – do you time from the pick-up all the way to around 360 crank degrees later?
    on SRX-600, first pick-up is at 34 degrees….
    so to fire spark at 40 degrees, fire it 354 degrees after the pick-up
    and to fire the spark at 10 degrees, fire it 384 after the pick-up

    BUT during kick-starting, you can’t calculate the engine speed because it’s only one or two engine revolutions – so you fire the spark on the pick-up… right? So could be difficult to start without kick-back…

    So, can I do this ?
    connect to the second pick-up (wire back-to-front to make it appear positive….)
    have spark fired at the pick-up during kickstarting
    have an offset of ~22 degrees in my spark map…

    cheers
    Thom

    1. Hi Thom,

      Thanks for your interrest and for the infos about SRX.
      So a lot of questions there!

      >your AC-CDI V9 uses only the first pick-up signal, right?
      No it can use both first and second pickup signal too:
      The “idle” pickup that fire the SCR immediately
      +
      The “high rev” pickup that fire the processor and goes toward the curve

      >And there’s no way of knowing if the engine is at TDC-firing or TDC non-firing stroke,
      For sure !

      > so you always fire a spark at both firing point and at end-of-exhaust-start-of-intake…. right?
      Right, it’s called “wasted spark system

      >at low engine speed, ignition is fired on the second (negative) pick-up
      Right , but it does not use absolutely the (negative) signal! I don’t know if Yamaha’s cdi use the neg or the pos. but I use the positive signal or the second/idle pickup on mine

      >below around 2000rpm, this delayed discharge happens after the second (negative) pick-up has already fired the spark, so nothing happens
      Right
      On Yamaha: I don’t know exactly if the first pickup (high rev) is not use at all below 2000 as it is not detected by the CDI (signal too small) or if it trigger a spark AFTER the one sent by the idle pickup

      On mine: Totally! “this delayed discharge happens after the second (POSITIVE) pick-up has already fired the spark, so nothing happens”

      >as engine speed rises, the delay gets shorter… above around 2000rpm, this discharge happens before the second (negative) pick-up, so it fires the spark.
      Exact

      >When the second (negative) pick-up “fires”, it does nothing because the capacitor is already discharged
      Still discharged or not is not the point, the key is: a second spark during explosion stroke do nothing

      >above about 4000rpm, the analogue delay is effectively zero, so the spark fires on the first (positive) pick-up
      yes

      >So how does the AC-CDI V9 time the sparks?
      >Obviously, you use the time between first pick-up pulses to calculate the engine speed….
      Right

      > and then look up from the programmed graph what the spark timing should be…
      right

      >So – do you time from the pick-up all the way to around 360 crank degrees later?
      No. The processor use the time between the 2 last pickups, those from the revolution before.

      >on SRX-600, first pick-up is at 34 degrees….
      >so to fire spark at 40 degrees, fire it 354 degrees after the pick-up
      > and to fire the spark at 10 degrees, fire it 384 after the pick-up

      No, on XT600 the pickup is localized at around 38-40 deg btdc to spark at 34
      They setup the pickup slightly BEFORE the max advance needed.

      >BUT during kick-starting, you can’t calculate the engine speed because it’s only one or two engine revolutions
      Exact

      > so you fire the spark on the pick-up… right? So could be difficult to start without kick-back…
      No that where the “kick start” value come at play. It’s a number of milliseconds to way before sending the very first spark. It’s tunable by the customer

      Make sense?
      regards
      Thierry P

  5. Hi Thierry,
    sorry, a couple more questions!
    I watched the video how to program the unit via wireless – and I looked at the picture of the populated board

    1) if you connect 2 pickups (like XT600. SRX600 etc), how do you program the unit to know there are 2 pick-ups?
    or is it like this –
    PKP12 pickup always fires spark immediately (fixed milliseconds delay after 12-degree pickup…?)
    PKP36 pickup uses the programmed table for spark timing

    2) if only one pick-up connected,, connect to PKP36 pin on board, and unit knows no pick-up connected to PKP12, so during stating fires spark at fixed millisecond delay after PKP36 pick-up….. right?

    3) the table of spark timing vs engine speed….
    does it do linear interpolation between break-points, e.g.
    500 12
    1000 12
    2000 12
    3000 24
    etc…
    so at 2500rpm, do you get 18 degrees spark timing, or still 12 degrees…?

    4) can you change the speed break-points?

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