2006-03-14
        Notes and Erratas:
English
(Deutsch, hier klicken):

This site lists all 'official' notes and erratas published by Silicon Chip or any of the (former) DIY-CDI kit distributors:

SILICON CHIP:
There is known one bug in the original article as you can see at:
http://www.siliconchip.com.au/html/indexes/ne-97-98.htm
[...]
  Original Article: Multi-Spark CDI
 Published: September 1997
 Note or Errata: Ttransistor Q1 in the impulse tachometer circuit on page 30 should be labelled a BC327 and not BC337 as shown.
 Note Published: (05/99)
[...]
This note refers to Fig13 in the CDI article, it was page 30 publish first in September 1997 issue of Siclicon Chip.
Fig 13 of our reworked version of the article is fixed.


AUTOMOTIVE ELECTRONICS:
Later in an the elelctronic collection book 'AUTOMOTIVE ELECTRONICS'  (1998) the article was published again:
[...]
HALL TRIGGERING
As with the High Energy Ignition, the Hall effect trigger circuit shown in Fig.5 was originally designed to suit the Siemens HKZ101 sensor which is no longer available. However the circuit should be compatible with existing distributors using HALL EFFECT SENSORS:
[...]


DICK SMITH ELECTRONICS:
Fig.7 of Dick Smith Manual (kit K3307) is modified, because they recommend:
[...]
Note - Install 2 links beneath Transformer T1
[...]
Fig7 Detail

This manual includes also 2 rather detailed parts lists:
[...]
    Parts List for Multiple Spark CDI
1# PC board code ZA1159 (05309971), 112x144mm
1# diecast case, 171x121x55mm   
1# ETD29 ferrite transformer (T1) assembly (Philips 2 x 4312 020 3750  2 3C85 cores, 1x 4322 021 3438 1x former, 2 x 4322 021 3437 1 clips.)
1# Neosid iron powdered core 17-732-22 (L1)
2# cord grip glands
1# solder lug
6# 3mm x 15mm screws, nuts & star washers
5# TO-220 style insulating bushes
8# TO-220 insulating washers
1# length of red and black automotive wire
1# length of 0.63mm enamelled copper wire
1# length of 0.25mm enamelled copper wire
1# length of 0.7mm tinned copper wire
1# length of 1mm enamelled copper wire
10# PCB pins
1# heatsink cornpound
    Cable ties, solder                     
    Semiconductors
2# IR2155 self-oscillating half bridge drivers (IC1, IC2)
2# MTP3055E TO-220 12A 60V N-channel Mosfets (Q1, Q2)
2# IRF822/IRF830 T0-220 2A 500V N-channel Mosfets or equiv. (Q6, Q7)
3# BC337 NPN transistors (Q3-Q5)
5# 1N914 signal diodes (D1, D8, D9, D10, D11)
6# 1N4936 fast recovery 400V 1 amp diodes (D2-D5, D6, D7)
4# 75V 1W zener diodes (ZD1-ZD4), 1N4761
1# S14K 275CAC (VE17-2750k) (MOV1)
    Capacitors
2# 100µF 16VW electrolytic (-40°C to 105°C rated; Hitano EHR series or equiv.)
2# 10µF 63V or 100V MKT
2# 1µF 275VAC MKP X2
1# 0.47µF 63V MKT polyester (C3)
1# 0.15µF MKT polyester (C3)
1# 0.12µF MKT polyester (CS) (see text)
1# 0.1µF 63V MKT
1# 0.01µF MKT
1# 0.0047µF 63V MKT
1# 0.001µF 63V MKT
    Resistors (0.25W 1% unless specified)
2# 680kΩ
2# 180kΩ
2# 56kΩ
2# 33kΩ
1# 22kΩ
1# 13kΩ
4# 10kΩ
1# 2.2kΩ
2# 220Ω
3# 22Ω
2# 10Ω
    Optional
As constructors will use different terminating methods, hardware items such as automotive connectors, additonal wiring etc. have been made optional.
[...]
    Parts List for Reluctor, Points & Hall Effect trigger circuits
    Reluctor trigger circuit
1# 5.1V 400mW zener diode 1N5231 or 1N751 (ZD5)
1# 1N914 signal diode (D12)
1# 0.0022µF 63V MKT capacitor
1# 470pF 63V MKT capacitor
2# 47kΩ 0.25W 1% resistor
3# 10kΩ 0.25W 1% resistor
1# 390Ω 1W 5% resistor
1# BC337 NPN transistor (Q8)
    Points trigger circuit
1# 1N914 signal diode (D12)
1# 1N914 signal diode (D13) (optional; see text)
1# 0.01µF MKT capacitor
1# 47Ω 5W resistor
1# 47Ω W resistor (optional; see text)
    Hall effect trigger circuit
1# 1N914 signal diode (D12)
1# 820Ω 1/2W 5% resistor
1# 100Ω 0.25W 1% resistor
    Optional (Not supplied)
1# Bosch rotating vane assembly to suit distributor
1# Siemens HKZ101 Hall sensor


JAYCAR ELECTRONICS:
sold this kit (as KC5232) too. The manual was just a copy of the SC article, but they added some notes and erratas and a good part list which was included to the DIY-CDI article:
[...]
NOTES & ERRATA
»The hole on the PC board for securing the toroid L1, needs enlarging to 3mm to accommodate the fastening bolt/washer assembly.
»The two lµF MKP capacitors are slightly larger than those used in the Silicon Chip magazine prototype.
»The 22kΩ resistor that connects to Q6 is very close to one of the caps, although the cap easily mounts above the resistor lead without a problem. When questioned, Silicon Chip magazine felt that this should not pose a problem.
»The article mentions the use of a Siemens HKZ101 Hall-Effect sensor. Whilst not supplied with this kit, they are available separately from Jaycar Electronics, cat. ZD 900. The Bosch rotating vane also mentioned is available from most automotive spare part retailers.
»When mounting the completed PC board assembly in the case, we noticed that the copper track running near the top right hand corner of the board comes perilously close to the case's metal mounting shelf Silicon Chip magazine assures us that this is perfectly alright, as the track connects to chassis ground anyway.
»With a simple circuit addition, our Programmable Ignition kit, KC5202, can be used in conjunction with this CDI kit (contact the Kit Department for circuit details).
[...]
ADAPTOR CIRCUIT FOR THE KC5202 PROGRAMMABLE IGNITION AND KC5232 MULTI SPARK CDI IGNITION

Adaptor Circuit for programmable ignition
(Click to enlarge!)
Although recommended by the designer of the programmable ignition kit, this circuit is untested!
Parts List:
1# 56kΩ1/2W 1% Resistor Pack
1# 10kΩ 1/2W 1% Resistor Pack
1# 47Ω 5W 5% Resistor
1# 0.01 µF MKT Polyester Capacitor
1# 1N4148 Signal Diode Pack
1# 33V 1W Zener Diode
2# BC337 NPN Transistor x 2
1# 95 x 76mm Vero Board
[...]

If you're interested in this programmable ignition kit here you can get the manual:
pages1-5.zip (308kB), pages6-10.zip (367kB), pages11-14.zip (326kB)


Further information provided by SILICON CHIP:
Listed at the end of the site: click:

If you find any 'official' note. please let us know. Prefered including source:  DIY-CDI Yahoo-Group .
Thanks

Back to DIY-CDI index site



Deutsch:

        Anmerkungen und Irrtümer:
Auf dieser Seite sind alle Anmerkungen und Ergänzungen angeführt die 'offiziell' von Silicon Chip bzw den (früheren) DIY-CDI-Kit Versandhäusern veröffentlicht wurden:

SILICON CHIP:
Es gibt einen kleinen Fehler im Original-Artikel, beschrieben auf:
http://www.siliconchip.com.au/html/indexes/ne-97-98.htm
[...]
  Original Article: Multi-Spark CDI
 Published: September 1997
 Note or Errata: Ttransistor Q1 in the impulse tachometer circuit on page 30 should be labelled a BC327 and not BC337 as shown.
 Note Published: (05/99)
[...]
Diese Anmerkung nimmt Bezug auf Fg.13 des Artikels, war auf der Seite 30 als Silicon Chip den CDI-Artikel das erste Mal im September 1997 veröffentlichte.
Fig 13 unserer überarbeiteten Version des Artikels ist schon korrigiert.


AUTOMOTIVE ELECTRONICS:
Später erschien wurde der Artikel in einer Elektronik-Sammlung im Buch 'AUTOMOTIVE ELECTRONICS'  (1998) veröffentlicht:
[...]
HALL TRIGGERING
As with the High Energy Ignition, the Hall effect trigger circuit shown in Fig.5 was originally designed to suit the Siemens HKZ101 sensor which is no longer available. However the circuit should be compatible with existing distributors using HALL EFFECT SENSORS:
[...]


DICK SMITH ELECTRONICS:
Fig.7 vom Dick Smith Manual (Kit K3307) ist angepasst, weil sie im Bild darauf hinweisen dass man 2 Verbindngen unter/hinter dem Transformator anbringen soll.
[...]
Note - Install 2 links beneath Transformer T1
[...]
Fig7 Detail

Dieses Manual beinhaltet auch 2 ziemlich detailierte Bauteil-Listen:
[...]
    Parts List for Multiple Spark CDI
1# PC board code ZA1159 (05309971), 112x144mm
1# diecast case, 171x121x55mm   
1# ETD29 ferrite transformer (T1) assembly (Philips 2 x 4312 020 3750  2 3C85 cores, 1x 4322 021 3438 1x former, 2 x 4322 021 3437 1 clips.)
1# Neosid iron powdered core 17-732-22 (L1)
2# cord grip glands
1# solder lug
6# 3mm x 15mm screws, nuts & star washers
5# TO-220 style insulating bushes
8# TO-220 insulating washers
1# length of red and black automotive wire
1# length of 0.63mm enamelled copper wire
1# length of 0.25mm enamelled copper wire
1# length of 0.7mm tinned copper wire
1# length of 1mm enamelled copper wire
10# PCB pins
1# heatsink cornpound
    Cable ties, solder                     
    Semiconductors
2# IR2155 self-oscillating half bridge drivers (IC1, IC2)
2# MTP3055E TO-220 12A 60V N-channel Mosfets (Q1, Q2)
2# IRF822/IRF830 T0-220 2A 500V N-channel Mosfets or equiv. (Q6, Q7)
3# BC337 NPN transistors (Q3-Q5)
5# 1N914 signal diodes (D1, D8, D9, D10, D11)
6# 1N4936 fast recovery 400V 1 amp diodes (D2-D5, D6, D7)
4# 75V 1W zener diodes (ZD1-ZD4), 1N4761
1# S14K 275CAC (VE17-2750k) (MOV1)
    Capacitors
2# 100µF 16VW electrolytic (-40°C to 105°C rated; Hitano EHR series or equiv.)
2# 10µF 63V or 100V MKT
2# 1µF 275VAC MKP X2
1# 0.47µF 63V MKT polyester (C3)
1# 0.15µF MKT polyester (C3)
1# 0.12µF MKT polyester (CS) (see text)
1# 0.1µF 63V MKT
1# 0.01µF MKT
1# 0.0047µF 63V MKT
1# 0.001µF 63V MKT
    Resistors (0.25W 1% unless specified)
2# 680kΩ
2# 180kΩ
2# 56kΩ
2# 33kΩ
1# 22kΩ
1# 13kΩ
4# 10kΩ
1# 2.2kΩ
2# 220Ω
3# 22Ω
2# 10Ω
    Optional
As constructors will use different terminating methods, hardware items such as automotive connectors, additonal wiring etc. have been made optional.
[...]
    Parts List for Reluctor, Points & Hall Effect trigger circuits
    Reluctor trigger circuit
1# 5.1V 400mW zener diode 1N5231 or 1N751 (ZD5)
1# 1N914 signal diode (D12)
1# 0.0022µF 63V MKT capacitor
1# 470pF 63V MKT capacitor
2# 47kΩ 0.25W 1% resistor
3# 10kΩ 0.25W 1% resistor
1# 390Ω 1W 5% resistor
1# BC337 NPN transistor (Q8)
    Points trigger circuit
1# 1N914 signal diode (D12)
1# 1N914 signal diode (D13) (optional; see text)
1# 0.01µF MKT capacitor
1# 47Ω 5W resistor
1# 47Ω W resistor (optional; see text)
    Hall effect trigger circuit
1# 1N914 signal diode (D12)
1# 820Ω 1/2W 5% resistor
1# 100Ω 0.25W 1% resistor
    Optional (Not supplied)
1# Bosch rotating vane assembly to suit distributor
1# Siemens HKZ101 Hall sensor


JAYCAR ELECTRONICS:
verkaufte auch diesen Kit (unter KC5232). Das Manual war aber nur eine Kopie des SC-Artikels, aber sie fügten einige Anmerkungen und Ergänzungen dazu, sowie eine gute Bauteil-Liste die in den überarbeiteten DIY-CDI-Artikel eingebaut wurde:
[...]
NOTES & ERRATA
»The hole on the PC board for securing the toroid L1, needs enlarging to 3mm to accommodate the fastening bolt/washer assembly.
»The two lµF MKP capacitors are slightly larger than those used in the Silicon Chip magazine prototype.
»The 22kΩ resistor that connects to Q6 is very close to one of the caps, although the cap easily mounts above the resistor lead without a problem. When questioned, Silicon Chip magazine felt that this should not pose a problem.
»The article mentions the use of a Siemens HKZ101 Hall-Effect sensor. Whilst not supplied with this kit, they are available separately from Jaycar Electronics, cat. ZD 900. The Bosch rotating vane also mentioned is available from most automotive spare part retailers.
»When mounting the completed PC board assembly in the case, we noticed that the copper track running near the top right hand corner of the board comes perilously close to the case's metal mounting shelf Silicon Chip magazine assures us that this is perfectly alright, as the track connects to chassis ground anyway.
»With a simple circuit addition, our Programmable Ignition kit, KC5202, can be used in conjunction with this CDI kit (contact the Kit Department for circuit details).
[...]
ADAPTOR CIRCUIT FOR THE KC5202 PROGRAMMABLE IGNITION AND KC5232 MULTI SPARK CDI IGNITION

Adaptor Circuit fuer programmierbare Zuendung
(Ankllicken zum Vergrößern!)
Although recommended by the designer of the programmable ignition kit, this circuit is untested!
Parts List:
1# 56kΩ1/2W 1% Resistor Pack
1# 10kΩ 1/2W 1% Resistor Pack
1# 47Ω 5W 5% Resistor
1# 0.01 µF MKT Polyester Capacitor
1# 1N4148 Signal Diode Pack
1# 33V 1W Zener Diode
2# BC337 NPN Transistor x 2
1# 95 x 76mm Vero Board
[...]

Falls dich die programmierbare Zündung interessiert, hier kannst du das Manual ansehen:
pages1-5.zip (308kB), pages6-10.zip (367kB), pages11-14.zip (326kB)


Weitere Information direkt von SILICON CHIP:
Gelistet gleich unten: klick:


Wenn du weitere 'offizielle' Ergänzungen findest, lasse es uns bitte wissen. Am Besten mit Quellenangabe DIY-CDI Yahoo-Group .
Danke

 Zurück zur DIY-CDI Startseite

SC:


http://www.siliconchip.com.au/cms/A_102711/article.html
Multi-Spark CDI timing queries
Q: I recently purchased the CDI kitset as featured in the September 1997 issue of SILICON CHIP and have some questions about the unit to help me understand how it works.
What was the formula you employed to get the values for sparks presented as the product's specifications? I am unable to see how the above information is related to Table 1 (RPM vs. Spark No. & Duration) on page 23. For example, please provide a mathematical formula on how to get:
(a) four sparks covering 37Deg of crankshaft rotation at 4500 RPM for a 4-cylinder engine?
(b) eight sparks covering 20Deg of crankshaft rotation at 1400 RPM for an 8-cylinder engine? (M. R., via email).

A: The spark duration table is based on the fact that the there are always multiples of two sparks produced. The duration and spacing was measured with an oscilloscope when driving a standard ignition coil. The times may vary with different coils and the calculations will vary slightly from the measured values due to differences in charging the timing capacitors.
The crankshaft angle is derived by calculating the rotation of the shaft over the total spark duration.
For example, the four sparks at 4500RPM for a 4-cylinder engine gives 37Deg. At 4500RPM, the frequency of rotation is 4500/60 or 75Hz. This is a duration of 13.3ms. The duration of four sparks is about 1.3ms and so we have 1.3/13.3 x 360Deg = 35Deg .
The result for eight sparks at 1500RPM, giving 20 Deg of crankshaft rotation, is calculated similarly: 1400RPM is 23Hz or 43ms; eight sparks is 3.1ms and 3.1/43 x 360Deg is 25 Deg .
As you can see, the calculations do fit the measured values reasonably closely.

http://www.siliconchip.com.au/cms/A_102633/article.html
Replacement for Hall Effect sensor
Q: Could you tell where can I get the HKZ101 and MJH10012 required to build the High Energy Ignition – I don’t want to buy the kit, I have been offered alternatives, UGN3503U and MJ10012 respectively. Are they compatible?
Finally, how do you connect the Programmable Ignition Timing module to the Multi-Spark CDI? (D. S., Bandung, Indonesia).

A: The HKZ101 is obsolete and no longer available. Unfortunately, the UGN3503 is not the same and is unsuitable.
You can use the Honeywell 4AV16F Hall Effect Vane sensor but note that a rotating soft iron vane is also required to pass through this sensor. The Hall sensor is available from Farnell Electronics – www.farnellinone.com
The MJH10012 is available from Jaycar – contact kits@jaycar.com.au
Interfacing the Programmable Ignition to the Capacitor Discharge Ignition requires two connections as follows: (1) connect the output of the trigger circuit to the points input of the Programmable Ignition; and (2) connect the Programmable Ignition output to the main circuit at the point marked "To Trigger Circuit"; ie, to the 10kΩ base resistor for Q4.

http://www.siliconchip.com.au/cms/A_101846/article.html
Fitting CDI to a Mazda rotary
Q: In John Clarke's article on the Multi-Spark CDI system in the September 1997 issue of SILICON CHIP, he refers only to using the kit in vehicles equipped with a distributor. I would like to use this kit in a Mazda that has a 13B rotary. The 13B has no distributor but fires the four plugs directly from two coils - each coil having two plug leads coming from it. One coil fires the "leading" set of plugs while the other fires the "trailing" set of plugs. It is relatively common on the 13B's to use the American MSD 6A ignition amplifier running through the leading coil only. (Amplifiers on the trailing coil are not recommended). Any advice would be greatly appreciated. (H.W., via email)
A: You will need two kits - one for each coil. Alternatively, you could just use one kit to fire the coil for the leading spark plug in each chamber.


Motorbike CDI wanted
Q: Can you please advise where I might find a circuit design for a simple Capacitor Discharge Ignition system? I want to fit one to a motor-cycle. It has a charging coil, already in the alternator, a pickup coil, for triggering but it doesn't have a battery.(J.P., via email)
A: The only CDI system we have described is the Multi-Spark CDI in the September 1997 issue but it does require a battery and it isn't simple. We understand that you want a magneto-charged CDI system (as on some modern bikes) but unfortunately we have not described a suitable circuit. If sufficient readers are interested in such a project, we'll have a look at developing a suitable circuit.


http://www.siliconchip.com.au/cms/A_30842/article.html
CDI for vintage motorbikes
Q: Back in July 1975, "Electronics Australia" came up with a modified design of the August 1970 CDI. I made up some of these and they are still running. I have only had one failure of a polycarbonate capacitor and even this was no drama as I had a spare in place. 28 years is not a bad effort and still going.
I have a collection of vintage motor motorcycles that used to have magnetos; ie, no distributor. I modified the EA circuit to the extent that I had two "steering diodes" just after the bridge rectifier. Each steering diode went to trigger circuits and hence to individual HT coils for each cylinder (twin cylinder 50° V). This works just fine.
What I would like to know is could the Programmable Ignition Module that's used to enable electronic advance (SILICON CHIP, March 1996) be used to interface with the 1975 CDI? I love CDI as it fires oily plugs, etc that abound on old bikes, no matter how good the engine condition is.
Failing that, I know that it does work with your High Energy Ignition (SILICON CHIP, June 1998). The problem is that old bikes do not have the kind of generation power of cars so that current draw has to be considered. The High Energy Ignition kit has provision for two sets of points. Could I use that feature to fire a 2-cylinder motor cycle with no high tension distributor cap? In other words, use a HT coil with two HT leads, having a waste spark on the exhaust of the cylinder that is not on compression (like a Harley)? I would dearly love to get rid of the mechanical advance unit that wears considerably. (D. A., via email).

A: Stick with your simple approach. Do not even consider the HEI as it needs heaps of current and won't necessarily do a better job of firing oily plugs. Don't bother with the PIT module either - it's too much trouble. You will need to build an interface to allow it to drive the old CDI and you need to derive 5V for it too.


http://www.siliconchip.com.au/cms/A_30315/article.html
How to increase Multi-Spark voltage
Q: I am interested in building the Multi-Spark CDI project from the September 1997 issue of SILICON CHIP. I was wondering about modifying it slightly. I'm wanting to increase the primary voltage from 300V to around 425V or so. Is this possible? The reason for this is to increase the output energy from 45mJ. Most commercial units put out 420V to 525V for the primary. (S. M., Invercargill, NZ).
A: The voltage can be increased by another 75V using an extra 75V zener in series with ZD1-ZD4. We do not recommend going above this voltage as the capacitor is not rated for more volts. You will need to add about 50 more turns on the secondary of T1 as well.


http://www.siliconchip.com.au/cms/A_101717/article.html
Bypass capacitors for Multi-Spark CDI
Q: I have a problem with the Multi-Spark CDI system featured in "Electronic Projects for Cars, Volume 2". Here in Thailand I cannot get the 10µF 63V MKT capacitors for decoupling the DC supply to the transformer (see page 82, Fig.2). Is it OK to change these to 1µF 63V MKT? (P. A., Amper Muang, Thailand).
A: 10µF capacitors must be used rather than 1µF. These are MKT types and are necessary for correct bypassing of the high frequency switching artefacts on the DC supply. Alternatively, low-ESR 10µF 25V electrolytics could be used.
Farnell Electronics sell these MKT capacitors, Cat. 814-155. Refer to: www.premierfarnell.com


http://www.siliconchip.com.au/cms/A_102847/article.html
Reluctor problem with Multi-spark CDI
Q: I have just put together the Multis-park Capacitor Discharge Ignition as published in the September 1997 issue of SILICON CHIP and I have come across some problems. There is no output from the coil (standard type) and the transformer I wound makes a buzzing sound.
Here are the DC voltages I measured (all taken from left to right (Q1 on the left) looking down on the devices bolted to the heatsink):
Q1 - 9.5V, 12.3V, 15.5mV.
Q2 - 1.4V, 12.1V, 17.1mV.
Q6 - 13.8V, 298.3V, 14.1V.
Q7 - 9.4mV, 14.2V, 9.1mV.
IC1 - pin 1 8.3V, pin 2 8.0V, pin 3 0.9V, pin 4 14.7V, pin 5 1.5V, pin 6 15.7mV, pin 7 8.12V, pin 8 8.3V.
IC2 - pin 1 15.3V, pin 2 22.2V, pin 3 12.5V, pin 4 9.1mV, pin 5 9.1mV, pin 6 13.2V, pin 7 13.2V and pin 8 15.1V.
The current draw without the coil is about 3.04A. The ignition pickup is a standard magnet/reluctor from a late-model Chrys-ler 360 engine. (M. K., via email).

A: The 300VDC supply is being correctly produced by your cir-cuit as there is 298V at the drain of Q6. This means that all the circuitry, including IC1 and Mosfets Q1 & Q2, is operating cor-rectly. It is normal for the transformer to buzz as it is switched on and off to maintain regulation. We assume that the 14.7V at pin 4 of IC1 is actually 14.7mV as it should be close to zero.
It would seem likely that your problem is in the reluctor pickup circuit. Check that ZD5 has 5.1V across it and that you have the correct value resistors inserted. You can simulate firing the coil by connecting a momentary short between collector and emitter of Q8. Alternatively, connect a momentary short between chassis and the anode of diode D12.
The coil should give a spark provided that there is a path-way from the high tension output to ground. To provide that, insert a paper clip into the coil's high tension output and bend it so that there is about a 2mm gap to the coil's negative terminal. We do not recommend having an open circuit high tension output (no spark pathway) as the coil may break down internally.


http://www.siliconchip.com.au/cms/A_101741/article.html
Is CDI dangerous for a motor bike?
Q: I built the HEI (high energy ignition) kit for my Falcon not too long ago. I am very impressed with it. Now I would like to try something different and build the Multi-Spark Capacitor Discharge Ignition (CDI) described in September 1997, for a motor bike. I have a few problems that you may have answers for. The bike that I would like to put this on has a 4-cylinder 250cc 16-valve engine.
My main concern is that it is such a small engine and the high energy spark may arc to the aluminium head and damage it in the long term. The spark plugs under the normal twin-coil system produce a rather pathetic spark at higher revs.
Spark plug sizes are somewhat smaller than that of a car. The cylinder has a small 30mm stroke. Peak revs are at 17,000 rpm after which it redlines to 19,500 rpm. The cylinder configuration is two up, two down; ie, two outer cylinders up while the two centre cylinders are down. They fire in a 1 3 4 2 sequence. Do you have any comments or suggestions?

A: While the CDI does have high energy, the actual spark voltage depends on the cylinder pressure. When the engine is under load, the cylinder pressures are higher and the voltage across the spark plug will rise to a higher voltage before it fires. But there is no danger of damage to the cylinder heads, even if there was an arc-over, which is highly unlikely.


Reluctor problem with multi-spark CDI
Q: Having completed the Multi-Spark Capacitor Discharge Ignition (SILICON CHIP, September 1997), it appears the triggering from my reluctor distributor is not happening. What could be wrong? The distributor is fine and swapping the reluctor wires over to it does not help.
When power is first applied there is a discharge into the coil, as I can hear it and see it with my timing light. On testing the inverter circuit to your
recommendations, I can measure 300V between the case and the tab of Mosfet Q6. (W. M., via email).

A: The reluctor signal sensitivity can be altered by changing the 47kO resistor which connects from the cathode of ZD5 to the other 47kO resistor which connects to the base of transistor Q8. Use a 200kO trimpot first and adjust it until the ignition fires. Then replace the trimpot with a fixed value resistor of the same value.
You can buy products mentioned in this article here :
RN3470 : RXE250 112W POLYSWITCH


http://www.siliconchip.com.au/cms/A_102419/article.html
Insufficient signal from reluctor
Q: I have one problem with the Multi-Spark CDI system described in the September 1997 issue. I connected it up to a reluctor from a Chrysler and there is no output from the coil. Then I shorted out the wires for the pickup and got a spark from the coil. I then tried it on a Falcon XF with reluctor and it worked perfectly. The resistance on the Chrysler pickup is about 460O and on the XF it is about 1.2kO.
I looked at the trigger input for the ignition system featured in the June 1998 issue and noticed there was a 2.2kO resistor in it but the equivalent resistor in the September 1997 circuit was 10kO. I made the change anyway but still no go. There doesn't seem to be enough pulse from the Chrysler pickup. Can I modify the circuit so that it will work properly? (M. K., via email).

A: The reluctor signal is usually quite substantial at around 30V peak-to-peak and so the circuit should operate. The actual resistance of the reluctor coil does not indicate much since the output is dependent upon the strength of the magnet associated with the reluctor, the number of turns on the coil and the reluctor gap, as well as the rotational speed.
The sensitivity of the reluctor trigger circuit can be increased by reducing the value of the 47kO resistor at the cathode of ZD5. This will reduce the level of current holding Q8 on when there is no signal from the reluctor. You could try using a 220kO trimpot and adjusting it until the circuit works or try various values from 68kO to 220kO.
The 2.2kO resistor you refer to is used in the collector of the transistor and will not affect the sensitivity of the reluctor circuit. Either value could be used here.
By the way, Chryslers are pretty old now; it is possible that the reluctor is faulty or you are using reversed connections to the circuit. Try swapping the reluctor leads.

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