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High-Energy Multi-Spark CDI For Performance Cars Pt.2: By JOHN CLARKE Six Versions To Suit Your Car’s Trigger Source In Pt.1 last month, we introduced our new High-Energy MultiSpark CDI and described its operation. In this article, we give the assembly details for six different versions to suit your car’s trigger source and describe the installation. T HE ASSEMBLY of the Multi-Spark CDI is straightforward, with all parts installed on a double-sided PCB coded 05112141 (110.5 x 85mm). This PCB can be obtained either as part of a complete kit (ie, from parts retailers) or can be purchased from the SILICON CHIP Online Shop. Fig.5 and Figs.6(a)-6(e) show the 38  Silicon Chip parts layouts to suit different ignition pick-up versions. It’s simply a matter of building the version to suit the ignition pick-up in your car. The first step is to install surface mount chips IC1, IC2 & IC3. These are in SOIC packages, so they are not that difficult to solder in place due to their relatively wide 0.05-inch pin spacing. Each IC is mounted on the top of the PCB and must be orientated as shown on Fig.5. Note that pin 1 is difficult to discern on IC3. However, if you look at the end profile of the IC, there will be a chamfer down one edge. This side has pins 1-4. To solder an IC in place, you will need a soldering iron with a fine tip siliconchip.com.au + 10Ω TC4427 1 µF MMC (SEC.) 4007 4007 D2-D5 TO CHASSIS EYELET 680k Low ESR MULTISPARK CDI Q4 1 µF X2 C1 = 470nF FOR 8 CYLINDERS; 150nF FOR 6 CYLINDERS; 120nF FOR 4 CYLINDERS – + Coil - C 2014 Q3 Chassis 100 µF MOV1 180k 4148 * 100nF X2 680k 22Ω IC3 4007 22Ω 33k 1W L6571 100 µF 180k D9 2.2k D6 1 4.7nF C1 4007 S1 4007 10Ω 100 µF T1 13k 56k BC337 33k 1W 33k 4148 Tacho 10k S2 14121150 47k 5.1V ZD3 10k GND BC337 S1 F1 Q7 Q5 D8 +12V 100nF X2 F1 BC337 10k Q6 F2 100k 100k 2 .2 nF FOR NO MULTISPARK = 15nF *C1 out 270k ZD2 10k 1k 470pF +12V 10k TP1 VR1 270k VR2 IC2 1 75V 10k 150Ω 4148 +5V R,K H+,A TRIG. 10k 150Ω D7 10k TO TACHO 47k 1nF 3x 100nF TO RELUCTOR COIL 10 µF 10k 1 µF MMC 1 1M 4700 µF Q2 ZD1 16V IC1 TL494 1M 1M 47k 4.7k 4004 8.2k Q1 10Ω 4.7k D1 TO COIL + WARNING: COIL OUTPUT OPERATES AT HIGH VOLTAGE Fig.5: follow this PCB layout diagram if your car’s distributor has a reluctor pick-up. Be sure to install the three SMD ICs (IC1-IC3) first and note that capacitor C1 must be chosen to suit the number of engine cylinders. Alternatively, leave out C1 and change the adjacent 4.7nF capacitor to 15nF if you wish to disable the multi-spark feature. and some “no-clean” flux paste. Begin by carefully placing the IC on top of its pads, ensuring that its orientation and alignment are correct. That done, place a dab of flux paste on one of the corner pins, then put a little solder on the tip of your soldering iron and touch the pin gently, without disturbing the IC. The flux paste should help “suck” the solder onto that pin and pad. Now check the IC’s alignment. If it’s out, reheat the joint and gently nudge it into place. Once the alignment is good, use the same technique to solder the diagonally-opposite pin. It’s then just a matter of soldering the remaining IC pins and cleaning up any bridges using solder wick. Refresh the joints on the first two pins you soldered, too. Adding no-clean flux paste is recommended for both procedures; when soldering the pins, it reduces the chance of bad joints. Finally, clean off any excess flux using an appropriate solvent (metho will do in a pinch) and check the joints under magnification to ensure that solder has flowed properly onto every pin and pad. Once the ICs are in place, the through-hole parts can be installed, starting with the resistors, diodes and zener diodes. Table 1 shows the resistor colour codes but you should siliconchip.com.au also check each one with a multimeter before fitting it to the PCB. Be sure to orientate the diodes and zener diodes as shown on Figs.5 & 6. The zener diode type numbers are shown in the parts list. Mosfets Q1-Q4 are next on the list. These must all be installed so that the tops of their metal tabs are 20-25mm above the PCB. The easiest way to do that is to first loosely fit all the devices in place, then rest the board upside down on 20-25mm-high supports (one at either end). The Mosfet devices can then be pushed down so that their tabs rest against the bench-top and their leads soldered. Once these parts are in, you can install the capacitors. Note that the electrolytic types must be orientated with the correct polarity (ie, negative lead towards the top edge of the PCB in each case). Note also that the 4700µF and 100µF capacitors must be low-ESR types. Multi-turn trimpot VR1 can now go be fitted. It goes in with its screw adjustment end towards the bottom edge of the PCB (ie towards Q7). Transformer winding Fig.7 shows the transformer details. It’s made up by first installing three windings on an ETD29 13-pin bobbin: a 240-turn secondary winding and two primary windings. The bobbin is then fitted to two N87 ferrite cores to complete the assembly. The secondary winding goes on first and is wound using 240 turns of 0.25mm-diameter enamelled copper wire (ECW), about 20m long. The first step is to scrape away about 10mm of the insulation from one end using a sharp hobby knife. This end is then soldered to pin 10 (S1) on the 7-pin Warning – High Voltage! This circuit produces an output voltage of up to 300V DC to drive the coil primary and is capable of delivering a severe (or even fatal) electric shock. DO NOT TOUCH any part of the circuit or the output leads to the coil from CON2 while power is applied. To ensure safety, the PCB assembly must be housed in the recommended diecast case. This case also provides the necessary heatsinking for the four Mosfets. January 2015  39 75V 270k ZD2 270k 1k 33k 1W 33k 1W 5.1V 180k 4148 4148 4148 D9 D7 ZD3 2.2k 10k 4148 270k ZD2 270k 75V TP1 D9 33k 1W 180k 4148 * C1 D7 4148 4.7nF 4148 BC337 33k 1W 13k (D) CRANE OPTICAL PICKUP TRIGGERING 75V 270k ZD2 270k 13k BC337 180k 4148 4148 * C1 D9 10k BC337 4.7nF Q5 D8 Q6 33k 1W 33k 56k 33k 1W 10k D7 Tacho FOR NO MULTISPARK = 15nF * C1 out 4148 GND TACHO TP1 100k 5.1V PHOTODIODE ANODE 150Ω VR1 22k LED CATHODE 150Ω +5V R,K H+,A TRIG. +5V Fig.6(a)-(e): here’s how to mount the parts on the input section of the PCB to suit other ignition trigger types. It’s just a matter of choosing the layout to match your car’s ignition trigger and then mounting the remainder of the parts as shown on Fig.5. Note that the 100W 5W resistor used in the points triggering version should be secured to the PCB using neutral-cure silicone, to prevent it from vibrating and fracturing its leads and/or solder joints. 33k 56k Q5 D8 BC337 (C) ENGINE MANAGEMENT TRIGGERING 5.1V ZD3 10k 4148 180k 4148 * C1 10k ZD3 33k 1W FOR NO MULTISPARK = 15nF *C1 out Q6 D9 BC337 TACHO 150Ω 100k D7 4148 2.2k 10k BC337 C1 VR1 4.7nF Q5 D8 Q6 * 22k 75V 270k ZD2 270k 13k GND Tacho Tacho 56k LED ANODE PHOTODIODE CATHODE GND GND 33k 33k 1W 100k 10k 4.7nF 150Ω +5V R,K H+,A TRIG. +5V R,K H+,A TRIG. TACHO TP1 VR1 FOR NO MULTISPARK 15nF *C1= out 13k (B) HALL EFFECT OR LUMINITION TRIGGERING (A) POINTS TRIGGERING ENGINE MANAGEMENT SYSTEM 33k 56k BC337 BC337 120Ω C1 180k 4148 * D9 BC337 BC337 10k Q5 D8 Q6 D7 4148 2.2k 10k 4.7nF Q5 D8 Q6 FOR NO MULTISPARK = 15nF *C1 out 2.2k 13k TP1 100k 120Ω 56k TACHO 150Ω VR1 2.2k 33k 33k 1W 10k Tacho Tacho FOR NO MULTISPARK = 15nF *C1 out 33k 1W SIG GND 150Ω 100Ω 75V 270k ZD2 270k 100 Ω 5W (POSITIVE SUPPLY) H+ GND GND TACHO 100k +5V R,K H+,A TRIG. +5V R,K H+,A TRIG. POINTS TP1 VR1 (E) PIRANHA OPTICAL PICKUP TRIGGERING side of the bobbin (see Fig.7). The next step is to wind on four 60turn layers. Begin by winding the wire clockwise, with the turns placed sideby-side, until the first 60-turn layer is completed. The winding should end up near the edge of the bobbin on the opposite side to the S1 start pin. Cover this winding with a single layer of insulation tape, taking care 40  Silicon Chip to also cover the start of the wire as it comes down from the bobbin pin. The next 60-turn layer can then be wound on in the same clockwise direction, again with the wires close-wound and laid side-by side. Cover this winding with another single layer of tape, then complete the other two 60-turn layers in exactly the same manner, finishing with another layer of tape. The end of the winding is now trimmed, stripped of insulation and soldered to pin 8 (F1), as shown. As before, make sure that the wire end is covered with a layer of insulation tape as it exits from the bobbin to connect to the pin. The idea is to make sure that the secondary winding will be electrically isolated from the primary windings. siliconchip.com.au This inside view shows the completed High-Energy Multi-Spark CDI with the parts installed for a reluctor pick-up trigger (see Fig.5). Be sure to use heavy-duty automotive cable for the external wiring connections. 1 6 60 TURNS EACH LAYER 7 F1 8 FIRST WIND THE SECONDARY, 5 USING 0.25mm ENAMELLED 4 COPPER WIRE: FOUR 60 -TURN LAYERS, STARTING FROM PIN 10 AND ENDING AT PIN 8 . PLACE ONE LAYER OF PLASTIC 3 INSULATING TAPE OVER 2 EACH LAYER. (SEC.) 9 S1 10 11 12 1 2 THEN WIND THE PRIMARIES, USING EIGHT TURNS OF 1mm ENAMELLED COPPER WIRE FOR EACH (WOUND TOGETHER – I.E., BIFILAR FASHION). TERMINATE THE START WIRES AT PINS 13 & 1 2 AND THE FINISH WIRES AT PINS 2 & 1 . 13 ETD29 FORMER UNDERSIDE (PIN SIDE) VIEW 7 6 5 F1 8 4 (SEC.) 9 S1 10 11 3 S2 12 2 F1 1 F2 (PRIMARY) (8 TURNS EACH) S1 13 ETD29 FORMER UNDERSIDE (PIN SIDE) VIEW Fig.7: the winding details for transformer T1. The secondary is wound first using four 60-turn layers of 0.25mmdiameter enamelled copper wire (ECW), starting and finishing at pins 10 & 8. The primary is then wound on using eight bifilar turns of 1mm-diameter ECW, starting at pins 13 & 12 and finishing at pins 2 & 1 respectively. The primary windings are wound using two separate 600mm lengths of 1mm ECW. Start by scraping about 10mm of insulation from one end of each wire, then wrap and solder them to pins 13 & 12 on the bobbin. The two primary windings are now wound on together (ie, bifilar wound). It’s just a matter of winding on eight turns and then connecting the wire ends to pins 1 & 2. Note that the wire that starts at S1 (pin 13) must connect to F1 (pin 2), while the wire from S2 (pin 12) must connect to F2 (pin 1). siliconchip.com.au You can identify the windings using a multimeter. There should be close to 0Ω between S1 & F1 and close to 0Ω between S2 & F2. Conversely, there should be high impedance (>1MΩ) between S1 & S2 and between the two primary windings and the secondary. Once the primary has been completed, cover this winding with a single layer of insulation tape cut to fit the inside width of the bobbin. It’s then just a matter of sliding the two ferrite cores into the bobbin and securing them in place using the supplied clips. The transformer assembly can now be installed on the PCB. It can only go in one way, since one side of the bobbin has six pins while the other has seven. Be sure to push the transformer all the way down onto the board before soldering its pins. The PCB assembly can now be completed by soldering long lengths of heavy-duty automotive cable to the PCB wiring points for the +12V supply, trigger inputs, coil connections and tacho connection. The chassis connection (near the coil connections) goes to January 2015  41 SILICONE WASHER M3 x 10mm SCREW INSULATING BUSH M3 NUT Q1-Q 4 PCB CASE Fig.8: the mounting details for Mosfets Q1-Q4. The metal tab of each device must be insulated from the case using an insulating bush and silicone washer. Do the mounting screws up firmly, then use a DMM to make sure each tab is indeed insulated from the case. a solder lug that’s secured to the case, so this lead can be kept short. Preparing the case The completed PCB assembly is housed in a diecast metal case measuring 119 x 94 x 57mm. This has to have a number of holes drilled in order to mount the PCB, secure the tabs of Q1Q4 and fit cable glands. Start the case preparation by drilling the PCB mounting holes. To do this, first place the PCB assembly inside the case and mark out the four corner holes in the base. That done, remove the PCB, drill these holes out to 3mm diameter and remove any burrs using an oversize drill. These holes should then be countersunk on the outside of the case, to accept M3 countersink head screws. Next, secure four M3 x 9mm tapped spacers to the PCB mounting holes using M3 x 6mm pan-head screws, reposition the PCB inside the case and mark out the tab mounting hole positions for Q1-Q4. Drill these out to 3mm diameter and lightly countersink them using an oversize drill to remove any sharp edges on the holes. This step is vital to prevent the insulating washers that fit between the Mosfet tabs and the case from being punctured. While you are at it, drill a 3mm hole in the side of the case so that the earth solder lug can be attached. This lug can then be installed using an M3 x 6mm machine screw, nut and shakeproof washer. Holes are also required in the lefthand and righthand ends of the case to accept the two specified cable glands. These two 15mm-diameter holes should be located 15mm down from the top of the case and 50mm in from the rear. You can drill the cable gland holes in one step using a 15mm Irwin Speedbor drill. Alternatively, use a small pilot drill to start the holes, then carefully enlarge them to size using a tapered reamer. Remove any sharp edges and metal swarf using a rat-tail file. Once all the holes have been drilled, install the PCB in the case and secure the spacers to the base using four M3 x 6mm countersink-head screws fed up through the base. Mosfets Q1-Q4 can then be fastened to the sides of the case Table 1: Resistor Colour Codes   o o o o o o o o o o o o o o o No.   3   2   2   2   1   2   3   1   7   1   2   1   2   3 42  Silicon Chip Value 1MΩ 680kΩ 270kΩ 180kΩ 56kΩ 47kΩ 33kΩ 13kΩ 10kΩ 8.2kΩ 4.7kΩ 2.2kΩ 22Ω 10Ω 4-Band Code (1%) brown black green brown blue grey yellow brown red violet yellow brown brown grey yellow brown green blue orange brown yellow violet orange brown orange orange orange brown brown orange orange brown brown black orange brown grey red red brown yellow violet red brown red red red brown red red black brown brown black black brown as shown in Fig.8. In each case, this involves using a silicone washer and insulating bush to electrically isolate the device tabs from the case. Secure each tab assembly to the case using an M3 x 10mm machine screw and nut. You can also fit a shakeproof washer if you wish. Now check that the tab of each device is indeed electrically isolated from the case. That’s done simply by measuring the resistance between the case and each Mosfet tab using a multimeter. Each device should give a very high ohms reading, although the reading may initially be low and then quickly increase as the capacitors charge up via the multimeter’s leads. A permanent low ohms reading means there is a short between the tab of that particular device and the case. If that happens, undo the assembly, clear the fault (eg, metal swarf or a sharp edge on the mounting hole) and replace the silicone washer with a new one. Finally, trim and solder the chassis wire to the earth lug and attach it to the side of the case. The +12V lead should be fed through the left cable gland along with the trigger wires. The two ignition coil wires should pass through the right hand cable gland. Be sure to use heavy-duty automotive cable for all these connections and lace the wiring securely to ensure reliability.   Table 2: Capacitor Codes Value 100nF 4.7nF 1nF µF Value 0.1µF .0047µF 0.001µF IEC Code EIA Code   100n   104   4n7  472    1n  102 5-Band Code (1%) brown black black yellow brown blue grey black orange brown red violet black orange brown brown grey black orange brown green blue black red brown yellow violet black red brown orange orange black red brown brown orange black red brown brown black black red brown grey red black brown brown yellow violet black brown brown red red black brown brown red red black gold brown brown black black gold brown siliconchip.com.au Note that running the +12V lead through the same clamp as the ignition coil would induce high voltage spikes into the +12V supply, so don’t do this. Testing Installation Be sure to mount the CDI case in a splash-proof location where air flows over it and make sure that it is well away from the exhaust side of the engine. It can be secured inside the engine bay using self-tapping screws or you could use brackets. Make sure that the case is well-earthed to the vehicle chassis. Once it’s in place, connect the positive supply lead to the +12V ignition line and the trigger input to the ignition pick-up. The coil leads go to either side of the ignition coil primary. Disconnect any other wires that are siliconchip.com.au This view shows how Mosfets Q3 & Q4 are secured to the case for heatsinking. Make sure that their case mounting holes are free of any metal swarf before installing the insulating washers and mounting screws. Mosfets Q1 & Q2 are mounted in similar fashion (see Fig.8). SILICON CHIP HIGH-ENERGY MULTI-SPARK CDI WARNING: HIGH VOLTAGE OUTPUT If possible, use a current-regulated power supply to initially test the DCDC converter in the Multi-Spark CDI unit. And here a word of warning: this inverter produces around 300V DC, so don’t touch any part of the circuit while it is operating. For the same reason, it’s important not to touch the output wires to the coil. Before applying power, it’s a good idea to fit the lid on the box. Electrolytic capacitors have a nasty habit of exploding if they are installed with reverse polarity, so this simple step will protect your eyes. At the very least, wear eye protection if you intend operating this unit with the lid off. If everything is OK when power is applied, then power off again and remove the lid. VR1 now has to be adjusted to set the converter’s output to 300V. To do this, connect a multimeter between the chassis and test point TP1, then reapply power and adjust VR1 for a 300V DC reading (be careful not to touch any part of the circuit). For a reluctor pick-up, VR2 has to be adjusted so that the pick-up sensitivity is correct. That’s done as follows: (1) Connect the reluctor to the CDI. (2) Turn VR2’s adjustment screw anticlockwise by 10 turns, then adjust this screw clockwise until Q7’s collector drops to 0V. (3) Turn VR2’s adjustment screw anticlockwise so that Q7’s collector just goes to about 5V, then adjust VR2 anticlockwise by two more turns (this ensures that Q7 is not prone to switching on and off with no reluctor signal). Fig.9: the front panel artwork can be downloaded from the SILICON CHIP website, printed out and sandwiched between the case lid and a Perspex sheet. Use neutral cure silicone to secure the Perspex in place. part of the original ignition system. The tacho signal leads runs direct to the tachometer (again, disconnect the existing signal lead). Note that a reluctor coil pick-up must be connected with the correct polarity in order to give the correct spark timing. This is best determined by testing the engine. If it doesn’t fire, reverse the leads and try again. You may find that with the MultiSpark CDI installed, the spark timing is a little advanced, due to the CDI’s fast rise time. If so, you may need to retard the static timing slightly to prevent pinging or a slightly rough idle. Note that it’s always a good idea to turn the ignition on for one or two seconds before actually cranking the engine. This will allow IC3’s 100µF filter capacitor to fully charge and give the inverter circuit sufficient time to generate its 300V DC output. Once it’s all working, use neutral cure silicone to seal the lip of the case, the cable glands and any mounting screws. This will ensure that the case is watertight and ensure reliability. SC January 2015  43