Fullscreen HTML5Med Res (??MB)HTML4

Pt.2: By John Clarke Six Versions To Suit Your Car’s Trigger Input High-Energy Electronic Ignition System In Pt.1 last month, we introduced our new High-Energy Ignition System and described its operation. In this article, we give the assembly details for six different versions, to suit your car’s trigger input, including an ECU/coil tester version. T HE ELECTRONIC IGNITION is built on a PCB coded 05110121 and measuring 89 x 53mm. This is housed in a 111 x 60 x 30mm diecast aluminium case to give a rugged assembly. Two cable glands, one at either end of the case, provide the cable entry and exit points for the power supply, coil switching and input trigger leads. The first step is to check the PCB for any defects. You then have to decide which version you are going to build. There are six different versions and it’s important to choose the version that suits your car’s trigger sensor. For example, if your car has a distributor with a reluctor pick-up, use the layout shown in Fig.5. If it has a Hall Effect or Lumenition trigger, follow the layout of Fig.6. Similarly, if you are using an existing 5V trigger signal from your car’s 48  Silicon Chip ECU (electronic control unit), build the layout shown in Fig.10. This is also the version to build if you intend using the unit purely as a coil tester. Note that the same PCB is used for each version. It’s just a matter of installing the relevant input trigger parts to suit your car. Mounting the parts Begin the assembly by installing PC stakes at the external wiring points, test points TP1, TP2 & TP GND and at the +5V point (near REG1). The three 2-way pin headers for links LK1-LK3 can then be fitted, followed by the resistors. Table 1 shows the resistor colour codes but you should also check each one using a digital multimeter before soldering it in place. Follow with the IC socket, making sure it is orientated correctly but don’t install the PIC micro yet. The capacitors can then go in (orientate the two electrolytics as shown), then install crystal X1 and the trimpots. Note that the Reluctor version has an extra trimpot (VR3). This is a multi-turn trimpot and it must be installed with its adjusting screw in the position shown. Regulator REG1 and transistor Q2 (in the Reluctor version) can then go in. Be sure to fasten REG1’s tab to the PCB using an M3 x 10mm machine screw and nut before soldering its leads. IGBT mounting details Fig.11 shows the mounting details for IGBT transistor Q1. It’s secured to the base of the case, with its leads bent at right angles and passing up through the underside of the PCB. For the time being, simply bend Q1’s leads upwards through 90° and test fit siliconchip.com.au siliconchip.com.au 47k 22pF 22pF IC1 LK1 PIC16F88 1nF CASE/ CHASSIS COIL TO COIL NEGATIVE LK3 Q1 ISL9V5036P3 (UNDER) 1k 2.2k 47k 10k R4 GND LK2 1k 2.2nF +12V 10 F 2.2k 100nF TP2 Q2 BC337 TP GND 4MHz +12V X1 100nF 10k 1k R3 TP1 RELUCTOR VR2 10k RELUCTOR PICKUP VERSION TO RELUCTOR Fig.5: follow this PCB layout diagram if your car’s distributor has a reluctor pick-up. Note that Q1 mounts under the PCB and is secured to the bottom of the case using an M3 x 10mm machine screw and nut – see Fig.11. 4MHz 47k 22pF TP1 +12V IC1 2.2k LK1 PIC16F88 100nF TP2 1nF CASE/ CHASSIS COIL TO COIL NEGATIVE LK3 Q1 ISL9V5036P3 (UNDER) 1k 2.2k TP GND GND LK2 1k TRIG. +12V 10 F X1 100nF 1k R3 R2 100 100 F VR110k +5V 100k TACHO REG1 LM2940 22pF 470nF IGNITION 12 05110121 101150 C 2012 VR2 10k HALL EFFECT/LUMENITION PICKUP VERSION + SIGNAL GND TO HALL EFFECT OR LUMENITION MODULE Fig.6: this is the layout to follow if the distributor uses a Hall Effect device or a Lumenition module. Take care with component orientation. 4MHz 47k 22pF TP1 +12V IC1 2.2k LK1 PIC16F88 100nF TP2 1nF CASE/ CHASSIS COIL TO COIL NEGATIVE LK3 Q1 ISL9V5036P3 (UNDER) 1k 2.2k GND LK2 1k TRIG. +12V 10 F X1 100nF R3 R5 120 22k 100 F VR110k +5V 100k TACHO REG1 LM2940 22pF 470nF IGNITION 12 05110121 101150 C 2012 Installing the PCB Once the case has been drilled, fit 6.3mm tapped Nylon stand-offs to the PCB’s corner mounting holes using M3 x 5mm machine screws. That done, the next step is to fasten Q1 in place. As shown in Fig.10, its metal tab is insulated from the case using two TO-220 silicone washers and an insulating bush and it’s secured using an M3 x 10mm screw and nut. Do this screw up finger-tight, then install the PCB in the case with Q1’s leads passing up through their respec- 470pF 100 F TRIG. it to the PCB but don’t solder its leads yet. Its tab mounting hole must be clear of the edge of the PCB, as shown in the diagrams. That done, fit the PCB assembly inside the case and slide it to the left as far it will go, to leave room for Q1. The mounting hole positions for the PCB and Q1’s tab can then be marked inside the case, after which the PCB can be removed and the holes drilled to 3mm (hint: use a small pilot drill first). Deburr these holes using an oversize drill. In particular, Q1’s mounting hole must be slightly countersunk inside the case to completely remove any sharp edges. The transistor’s mounting area should also be carefully smoothed using fine emery paper. These measures are necessary to prevent the insulating washers which go between Q1’s metal tab and the case from being punctured by metal swarf or by a highvoltage arc during operation. Having drilled the base, the next step is to mark out and drill holes in the case for the two cable glands. These holes are centrally located at either end and should be carefully reamed to size so that the cable glands are an exact fit. You will also have to drill a 3mm hole for the earth connection in one end of the case. This goes in the end adjacent to the GND connection on the PCB – see photos. VR3 100k +5V PCBs: a PCB for the High Energy Ignition can be purchased separately from the SILICON CHIP Partshop. TACHO REG1 LM2940 100k 470nF IGNITION 12 05110121 101150 C 2012 TP GND Both Jaycar and Altronics will have full kits (including the case) available for the High Energy Ignition. The Jaycar kit is Cat. KC-5513 while the Altronics kit is Cat. KC-5513 VR110k Where To Buy Kits VR2 10k CRANE OPTICAL PICKUP VERSION LED A DIODE K GND (ANODE) (CATHODE) TO CRANE MODULE Fig.7: build this version of the ignition if your distributor has been fitted with a Crane optical pick-up. December 2012  49 VR110k +5V IC1 PIC16F88 1nF CASE/ CHASSIS COIL TO COIL NEGATIVE LK3 Q1 ISL9V5036P3 (UNDER) External wiring 1k 2.2k R4 GND LK2 1k 22k R6 TP GND LK1 120 +12V 10 F 2.2k 100nF TP2 LED K TRIG. 4MHz +12V X1 100nF 100 F TP1 47k 22pF +5V 22pF TACHO REG1 LM2940 100k 470nF IGNITION 12 05110121 101150 C 2012 VR2 10k PIRANHA OPTICAL PICKUP VERSION +5V LED K DIODE A (ANODE) (CATHODE) TO PIRANHA MODULE Fig.8: the Piranha optical pickup version is similar to the Crane version but note the different locations for the 22kW and 120W resistors. R1 100  5W 4MHz 47k 22pF TP1 +12V 2.2k LK1 IC1 PIC16F88 100nF TP2 1nF CASE/ CHASSIS COIL TO COIL NEGATIVE LK3 Q1 ISL9V5036P3 (UNDER) 1k 2.2k TP GND GND LK2 1k TRIG. +12V 10 F X1 100nF 100 F VR110k +5V 100k TACHO REG1 LM2940 22pF 470nF IGNITION 12 05110121 101150 C 2012 VR2 10k POINTS VERSION TO POINTS Fig.9: this is the points version. Secure the 100W 5W resistor (R1) to the PCB using neutral-cure silicone, to prevent it from vibrating and fracturing its leads and/or solder joints. 4MHz 47k 22pF TP1 +12V IC1 2.2k LK1 PIC16F88 100nF TP2 1nF CASE/ CHASSIS COIL TO COIL NEGATIVE LK3 Q1 ISL9V5036P3 (UNDER) 1k 2.2k TP GND TO 5V SIGNAL GND LK2 1k TRIG. +12V 10 F X1 100nF 100 F VR110k +5V 100k TACHO REG1 LM2940 22pF 470nF IGNITION 12 05110121 101150 C 2012 VR2 10k ECU/COIL TESTER VERSION Fig.10: the ECU (engine management) trigger version requires no additional input conditioning circuitry. In this case, the ECU trigger signal goes straight to pin 6 of IC1 via a 2.2kW resistor. Build this version also if you only intend using the unit as a coil tester, in which case the 5V trigger input isn’t needed. 50  Silicon Chip tive mounting holes. The PCB can now be secured in place using four more M3 x 5mm machine screws, after which you can firmly tighten Q1’s mounting screw (make sure the tab remains centred on the insulating washers). Finally, use your multimeter to confirm that Q1’s tab is indeed isolated from the metal case (you should get an open-circuit reading), then solder its leads to the pads on top of the PCB. All that remains now is to run the external wiring. You will need to run leads through the cable glands and solder them to the relevant PC stakes for the power, coil and input trigger connections. Note that the coil wire is the only wire that’s fed through that righthand cable gland (important to prevent interference due to high-voltage switching glitches, eg, by capacitive coupling into the power and trigger leads). The remaining leads (with the exception of the earth lead) must all be run through the other cable gland, at the trigger input end of the case. As shown in the photos, we fitted heatshrink tubing over the PC stake connections, to prevent the wires from breaking. So before soldering each lead, fit about 6mm of 3mm-diameter heatshrink tubing over it, then slide it over the PC stake and shrink it down after the lead has been soldered. The earth connection from the PCB goes to an solder eyelet lug that’s secured to the case using an M3 x 10mm screw, nut and star washer. This same screw also secures a quick connect lug on the outside of the case (see photo). Initial checks & adjustments Now for an initial smoke test – apply power to the unit (between +12V and GND) and use your DMM to check the voltage between the +5V PC stake and GND. It should measure between 4.85V and 5.25V. If so, switch off and insert the programmed PIC (IC1) into its socket, making sure it goes in the right way around. You can now do some more tests by connecting the car’s ignition coil between the +12V and COIL leads. The unit should be powered from a 12V car battery (or motorcycle battery), with the case connected to battery negative. The coil’s HT (high tension) output should be fitted with a paper clip (or similar) which is then positioned so siliconchip.com.au that it can spark back to the coil’s negative terminal over about a 5mm gap. Before connecting the +12V supply, set the dwell trimpot (VR1) fully anticlockwise and install a jumper on LK2 to enable the spark test mode. That done, apply power and slowly adjust VR1 clockwise. The sparks should start and gradually increase in energy with increased dwell. Stop adjusting VR1 when the spark energy reaches its maximum. This sets the dwell period to suit your ignition coil. Note that, during the spark test procedure, the spark frequency can be changed using VR2. Note also that when accelerating, the rapid change in the time between successive firings can cause the dwell to reduce. That’s because the micro determines when the coil is to be switched on, based on the previous period between plug firings. During acceleration, this period reduces for each successive firing. To counteract this reduction in dwell, the software dwell calculation also takes into account the rate of change in the period between firings. This ensures that the initial set dwell period is maintained under normal acceleration. However, you may need to set the dwell to slightly longer than “optimal” (by adjusting VR1 clockwise) to ensure sufficient dwell during heavy acceleration. M3 x 5mm SCREWS INSULATING BUSH PCB M3 NUT M3 x 6.3mm TAPPED NYLON SPACERS Q1 2 x TO-220 SILICONE INSULATING WASHERS M3 x 5mm SCREWS M3 x 10mm SCREW Fig.11: the PCB and IGBT (Q1) mounting details. Note that Q1’s metal tab must be insulated from the case using two TO-220 silicone washers and an insulating bush. After mounting, use a multi­meter (set to a low ohms range) to confirm that the tab is properly isolated; it must not be shorted to the case. That completes the dwell adjustment procedure. Link LK2 should now be removed, so that all three 2-pin headers (LK1-LK3) are open. Installation The Electronic Ignition box should be installed in the engine bay close to the distributor. Make sure that it’s well away from the exhaust manifold and the catalytic converter (if fitted), so that it doesn’t overheat. Use brackets and screws to secure the box to the chassis. That done, wire the positive supply lead to the +12V ignition supply, the negative earth lead to the car chassis (if necessary) and the trigger inputs to the trigger unit in the Table 2: Capacitor Codes Value 470nF 100nF 1nF 22pF µF Value IEC Code EIA Code 0.47µF 470n 474 0.1µF 100n 104 0.001µF    1n 102   NA   22p   22 distributor. The coil lead goes to the coil negative, replacing the existing switched negative lead. If you are using the Reluctor circuit, connect the Reluctor trigger unit, adjust VR3 fully anti-clockwise and measure the voltage at the trigger test point (TP TRIG). If the voltage is close This is the view inside the completed unit (reluctor pick-up version shown). Be sure to build it for good reliability by fitting heatshrink over the solder joints on the PC stakes and by fitting a cable tie to the leads as shown. Note that the lead to the coil negative is the only one that exits through the righthand cable gland. Table 1: Resistor Colour Codes o o o o o siliconchip.com.au No.   1   1   2   2 Value 100kΩ 47kΩ 2.2kΩ 1kΩ 4-Band Code (1%) brown black yellow brown yellow violet orange brown red red red brown brown black red brown 5-Band Code (1%) brown black black orange brown yellow violet black red brown red red black brown brown brown black black brown brown December 2012  51 Dwell vs TP1 Voltage 5 7: 5V 4 TP1 (V) 6: 3.6V 3 5: 2.92V 4: 2.68V 3: 2.21V 2 2: 1.08V 1 1: 0V 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Dwell (ms) Fig.13: you can check the dwell setting by measuring the voltage at test point TP1 and then reading the dwell period (in milliseconds) off this graph. The dwell is adjusted using trimpot VR1 to give maximum spark energy, as described in the text (see initial checks and adjustments). to zero, wind VR3 clockwise several turns until the voltage goes to +5V, then wind it another two turns clockwise and leave VR3 at that setting. Now check that LK1-LK3 are all open (ie, no jumpers installed), then try to start the engine. If it doesn’t start, try the invert mode by installing LK3. If you have a Reluctor pick-up, it’s important that the engine fires on the leading edge of the trigger signal. That edge should coincide with the leading edge of each tooth on the Reluctor ring as the distributor shaft rotates, otherwise the timing will usually be so far out that the car won’t start. In that case, you can either swap the Reluctor leads or install LK3 as described above. Once the engine starts, adjust the debounce trimpot (VR2) for best results. This adjustment should be set as low as possible (ie, set VR2 anticlockwise as far as possible). An increased debounce period will be required if the engine runs erratically and it’s just a matter of adjusting VR2 clockwise until smooth running is obtained. If that doesn’t do the trick, then the follow mode may be necessary. This is selected using LK1 and will typically be required for badly worn points or worn distributor shaft cam lobes and/ or shaft bearings. Note that, in the absence of trigger signals, the coil switches off after 1s for debounce settings of 2ms and less, or 52  Silicon Chip The quick-connect terminal at the right-hand end of the case provides a convenient connection point for the earth lead. after 10s for debounce periods greater than 2ms. The debounce setting can be measured by connecting a multimeter between TP2 and TP GND. As stated, VR2 sets the debounce period and the calibration is 1ms per 1V. the coil is able to cope with the continuous current that will flow through it for this period without overheating. A ballast resistor will prevent excessive current flow through coils that have a low resistance (ie, below 3Ω). Ignition coil Connecting a tachometer For most installations, it’s usually best to keep the original ignition coil and ballast resistor (if one is used). If you intend using a different coil, make sure it is suitable, especially if you intend setting the debounce period so that there’s a 10s delay before the coil switches off in the absence of trigger signals. In that case, it’s important that Finally, the Tacho output (top-right of the PCB) should be suitable for driving most digital tachometers. However, an impulse tachometer will require a signal voltage that’s derived from the negative side of the coil. If that doesn’t work, try operating the ignition unit in “follow” mode by installing a jumper SC across LK1. siliconchip.com.au