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High-Energy Electronic Ignition System; Pt.2 Six Versions To Build To Suit Your Car’s Trigger Input! Pt.2: By JOHN CLARKE Last month, we introduced our new HighEnergy Electronic Ignition System and gave the circuit details. This month, we give the assembly details and describe how to convert a points distributor to Hall effect pickup. T HE ELECTRONIC IGNITION is constructed on a PC board that measures 102 x 81mm and is coded 05112051. It is housed in a diecast metal box measuring 119 x 93 x 57mm. Before installing the parts, check the PC board against the published patterns and make sure that all the holes 68  Silicon Chip have been drilled. There should not be any shorts or breaks in the copper tracks. Make repairs if necessary. Depending on the type of trigger input, there are six different component layouts for the PC board – choose the one that is applicable to your car’s trigger sensor. For example, if your car has reluctor distributor, follow the component layout of Fig.9. If it has a Hall Effect device or Lumenition distributor (same thing), use the layout of Fig.10. Starting construction Start construction by installing PC stakes at the external wiring points and also insert and solder in the links. The three linking options use 3-way pin headers that are soldered in place. Next, install the resistors, using your multimeter to measure the values. The zener diodes can go in next. Be sure to install them with the correct orientation. Similarly, make sure that IC1’s socket is oriented correctly. Don’t insert the IC at this stage, however. siliconchip.com.au Fig.9: follow this parts layout diagram if your car’s distributor has a reluctor pickup. Fig.10: this is the layout to follow if the distributor uses a Hall Effect device or a Lumenition module. Take care with component orientation during assembly. The transistors are next on the list. Again, make sure they are oriented correctly. Q1 is mounted at full lead length, with its metal flange toward the edge of the PC board. siliconchip.com.au The capacitors can be installed next. Each electrolytic type must be installed with the polarity indicated. That done, install the crystal and trimpot(s). Once the board assembly is complete, position it in the case and mark out the four mounting holes. That done, remove the PC board and drill the mounting holes to 3mm. Deburr January 2006  69 Fig.11: this is the points version. Secure the 100W 5W resistors to the board using silicone, to prevent them from vibrating and fracturing their leads and/or the solder joints. Fig.12: the 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. each hole using an oversize drill bit, then fit a 9mm standoff to each mounting position with an M3 x 15mm screw passing through it from outside the 70  Silicon Chip case. The PC board is then fitted in place and temporarily secured using M3 washers and nuts. That done, mark out the position for Q1’s mounting hole, the earth connection on the side of the case and the cordgrip grommets at each end of the case, then remove the board siliconchip.com.au Fig.13: build this version if your distributor has been fitted with a Crane optical pickup. Fig.14: the Piranha optical pickup version is similar to the Crane version but note the different locations for the 22kW and 120W resistors. and drill these holes. Note that the cordgrip grommets need elongated holes and these can be shaped using a rat-tailed file. siliconchip.com.au The inside of the mounting hole for Q1 must be carefully deburred to remove any sharp edges that may puncture the insulating washer. A large diameter drill can be used by hand to do this. That done, you can then install the PC board and secure it using the star washers and nuts. January 2006  71 Converting From Points To A Hall Effect Sensor You can replace your existing points with a Hall Effect sensor – but be warned, it takes quite a lot of precision work! All the details are shown in Fig.12. First, rotate your engine so that the rotor button in the distributor is facing the high-tension outlet for cylinder number 1. Also note the direction that the rotor button moves when the engine is turned in its correct direction. Set the timing mark on the flywheel to the number of degrees before Top Dead Centre specified in the workshop manual and indicated by the engine block timing marks. Now place a mark on the edge of the distributor body to show where the timing mark on the rotor button arm is positioned. This sets the alignment for the Hall Effect modification. The distributor can now be removed from the engine. The Hall Effect sensor is designed to be used with a rotating vane that passes through the gap incorporated in its housing. The Hall sensor is mounted on the distributor advance plate and secured using the rivets incorporated on its housing. The rotating vane needs to be made so that it spins with the distributor shaft The rotor button assembly fits over the distributor’s camshaft, with the vanes passing through the Hall Effect sensor. and its vanes pass through the sensor gap. For this to happen, the rotating vane needs to be cup-shaped. The horizontal face has a hole to allow it to be placed on the distributor shaft and locate with the rotor button. The vertical section needs to have slots cut in it to appropriately trigger the sensor. The number of slots on the vane equals the number of spark-plugs for which the distributor caters. So a 4-cylinder car with four spark plugs will use four slots. These slots need to be evenly spaced around the circumference of the rotating vane. It is essential to be accurate here, as a 1° difference between slots represents 2° on the engine. A 4-cylinder engine will have each slot positioned 90° apart. 6-cyclinder and V8 cars will require slots spaced 60° and 45° apart, respectively. Making The Disk Making the disk is easier if you can start off with something that is already preformed. We used the tinplated backing from a high power potentiometer. A suitable one is the Jaycar RP-3975 15W potentiometer. This photo shows how the slotted Hall Effect sensor is rivetted to the vacuum advance plate inside the distributor. This provides us with a cup that is 40mm in diameter. All that is required is to drill out a hole in the top for the distributor shaft and cut the slots in the side. Mounting The Sensor When this has been done, the Hall sensor can be mounted on the distributor advance plate. The sensor needs to be located so that the centre of its slot is 20mm away from the centre of the distributor shaft. This will allow the 40mm diameter cup to spin without fouling the Hall sensor. Drill the two holes in the distributor advance plate and countersink the holes on the underside of the plate. This will allow space for the rivets in the Hall sensor to be peened over. Before riveting, check that the Hall Effect wires do not foul against the points cam (this happened in the distributor we were modifying!). To prevent this, the wires were passed under the Hall sensor by filing a small channel beneath the sensor, so that the wires could be fed through to the other side. The wires were then fed through a grommet in the distributor’s body. Rotating Vane The rotating vane should be placed over the distributor shaft and should sit on the top of the points camshaft. Check that there is sufficient clearance between the vanes and Hall sensor gap. If the cup needs to be higher than this, it can be placed over the rotor button shaft. In this case, the rotating vane must be electrically connected to the dis72  Silicon Chip siliconchip.com.au Fig.15: these diagrams and the accompanying photos show how to replace the points with a Hall Effect sensor and make the rotating vane assembly. Note that the slots in the vane must be accurately positioned – see text. tributor shaft to prevent static build up which may damage the Hall sensor. A small piece of tinplate soldered to the vane and bent so it passes up inside the rotor button to make contact with the distributor shaft is suitable. When the Hall Effect sensor has been mounted, place the rotating cup over the distributor shaft and hold it in place with the rotor button. Check that the vane spins freely through the Hall sensor slot. Now you are ready to align the disk. Rotate the rotor button to the alignment marks set previously. Remember, these indicate the centre position of the rotor button at Number 1 cylinder timing. Move the rotating siliconchip.com.au vane relative to the rotor button so that the gap is just leaving the centre of the Hall Effect sensor. Note that you must be turning the distributor in the direction that it travels when installed in the car. Mark the position on the rotating vane and rotor button using a marking pen (do not use a scriber on the rotor button or the high tension voltage may travel down this). We soldered in a couple of PC stakes inserted into holes drilled in the top of the vane, to align the vane position – these keyed into the locating slot in the rotor button. Gluing The Vane Finally, the rotating vane can be glued to the bottom of the rotor button using high-temperature epoxy resin. We used JB Weld epoxy steel resin, a 2-part epoxy. This is suitable for temperatures of up to 260°C. The quick-setting version can be used for temperatrures up to 150°C. January 2006  73 Fig.16: the metal tab of the Darlington transistor (Q1) must be insulated from the case using an insulating washer and bush. After mounting, use a multi­meter (set to a low ohms range) to confirm that the tab is properly isolated – ie, it must not be shorted to the case. Above: once your unit has been assembled, secure the wiring connections using blobs of silicone, to prevent breakages at the PC stakes. The 5W resistor(s) should also be secured using silicone, as can the LK1-LK3 pin headers (once you’ve selected the desired options). Cable ties should also help secure the leads, both inside and outside the case. Table 2: Capacitor Codes Value 100nF 10nF 1nF 2.2nF 470pF 33pF μF Code 0.1µF .01µF .001µF .0022µF   NA   NA EIA Code IEC Code   104 100nF   103 10nF   102 1nF   222 2n2   471 470p    33 33p The Darlington power transistor Q1 is secured to the case with an insulating bush and washer as shown in Fig.16. Next, attach the leads required for power, coil and input triggers. Note that the coil wire is the only wire passing through the end cord-grip grommet. The remaining wires pass through the other grommet (ignore the photos) – see Fig.17. The earth connection from the PC board goes to an eyelet lug that is secured using a screw, nut and two star washers, as shown in Fig.17. The various leads should all be secured using cable ties, along with beads of silicone at the solder stakes. This is necessary to prevent the leads from vibrating and coming adrift. Similarly, use silicone to secure the 5W resistor(s) to the PC board. Finally, install the links for LK1, Table 1: Resistor Colour Codes o o o o o o o o o o o No.   1   3   1   2   2   1   1   1   1   1 74  Silicon Chip Value 100kW 47kW 22kW 10kW 2.2kW 1.8kW 1kW 470W 120W 100W 4-Band Code (1%) brown black yellow brown yellow violet orange brown red red orange brown brown black orange brown red red red brown brown grey red brown brown black red brown yellow violet brown brown brown red brown brown brown black brown brown 5-Band Code (1%) brown black black orange brown yellow violet black red brown red red black red brown brown black black red brown red red black brown brown brown grey black brown brown brown black black brown brown yellow violet black black brown brown red black black brown brown black black black brown siliconchip.com.au Fig.17: this diagram shows the final assembly and external wiring details for the unit. Note how the 0V (ground) rail on the PC board is connected to one side of the case, with a lead then run from this point to the vehicle’s chassis. LK2 and LK3. Initially, you can place these in the standard, 0.5ms debounce and normal positions, respectively. Installation The Electronic Ignition box goes in your car’s engine bay, on the same side as the distributor. Make sure that the box is shielded from the heat of the exhaust manifold or catalytic converter (the internal components are rated to a maximum temperature of 125°C). 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’s chassis and the inputs to the trigger unit. Do not connect to the coil negative yet, however. Next, set VR1 fully anti-clockwise, then switch on the ignition and check that there is 5V between pins 5 & 14 on the IC socket. If this is correct, switch the ignition off and install IC1. Make sure that it is oriented correctly, with its notch matching the notch at one end of the socket. If you do this incorrectly, siliconchip.com.au you will blow the chip. Now connect your meter between the 0V PC stake near VR1 and the TP1 PC stake. Switch on and adjust VR1 for a reading of about 4V. This should set the dwell at around 6ms. Reluctor settings If you are using the reluctor circuit, adjust VR2 fully clockwise and measure the voltage at pin 6 of IC1. If the voltage is close to 0V, wind VR2 anti-clockwise several turns until the voltage goes to 5V. That done, wind it about two turns more anti-clockwise and leave VR2 at this setting. If the voltage is 5V when VR2 is fully clockwise, rotate VR2 fully anticlockwise and start to wind it clockwise until the voltage goes to 5V again. Then wind it two more turns clockwise. That done, switch off the ignition and connect Q1’s collector wire to the ignition coil’s negative. Starting Now try to start the engine. If it Darlington transistor Q1 is secured to the case using an M3 screw and nut. Make sure its tab is correctly isolated from the case metal – see Fig.16 doesn’t want to start, the sensor signal may be inverted. This can happen with Hall Effect sensors and optical sensors if the output voltage goes low at the point of firing. In this case, change link LK1 to the “invert” position. The reluctor circuit is designed to fire the coil when its output voltage swings negative. If the engine doesn’t start and you are using a reluctor, try swapping the reluctor connections. If you are using points and the engine does not run smoothly, try the 2ms debounce link setting. If the engine is January 2006  75 This is the view inside the prototype (reluctor version shown). Be sure to build it for good reliability by securing all leads and using star lockwashers at the positions indicated in the diagrams. still erratic, change to the points mode using LK3. Dwell adjust The amount of dwell required depends on the ignition coil used in your vehicle. To adjust this, set your multimeter to DC volts and connect the probes between the chassis and the negative terminal on the coil. Danger: you must use a multimeter Corrections There are several errors in the parts list published in Pt.1. In the main section, there should be three (not two) 100mF capacitors, the LM2940CT-5 regulator should be designated REG1 and there should be three (not two) crimp eyelets. In addition, the 22W resistor listed under the “Optical Pickup Version” heading should in fact be 22kW. rated for at least 300V and take great care not to make contact with the negative terminal of the coil! Set the idle so that the engine runs smoothly and adjust VR1 anti-clockwise until the engine begins to falter or until the voltage reading shown on the meter drops. Now slowly turn VR1 clockwise until the voltage rises and then remains at the same voltage, even though the dwell is increased slightly. Stop turning the trimpot at this voltage plateau. This setting provides the optimum dwell for your coil. If you wish, you can in fact set the dwell to a slightly greater value than this, to cater for resistance changes at the coil connections due to varying temperatures. So what did adjusting the pot act­ual­ ly do? What we are doing is measuring the average primary coil voltage. When the coil is charging, the voltage will Where To Buy Programmed PICs The programming code (ignition.hex) for the PIC16F88-E/P microcontroller used in this project will not be released or be made available on our website. Authorised kitsellers will supply pro­grammed micros as part of their kits. For people who do not wish to build the project from a kit, programmed micros will be available from SILICON CHIP for $25.00 including postage anywhere within Australia, or $30.00 by airmail elsewhere. 76  Silicon Chip be about 1.5V due to the drop across the ignition transistor (Q1). When the transistor switches off, there is a high voltage produced that is limited by the zener diodes to 300V. After the coil has discharged, the voltage will be at about 12V (or the battery supply) until transistor Q1 again switches on to recharge the coil. The coil will deliver its full energy if the dwell period is set so that the coil can charge fully. At this point, the average measured voltage will be at its highest. Increasing the dwell time further will not increase the coil’s energy but it may decrease the average measured voltage. This is because the extra dwell will have the coil negative terminal at 1.5V for longer, thus reducing the average measured voltage. Setting more dwell time than necessary will only heat up the coil without improving spark energy. Once the ignition is set up and running well, fit the lid onto the box. Conclusion Depending on the car to which you’re fitting the electronic ignition system, you can expect reduced points wear, a stronger spark, a cooler running coil and slightly better fuel economy and power. And that’s pretty darn good SC for the money and time spent! siliconchip.com.au