Electronic ignition - what is its advantage? Electronic ignition made of two parts Electronic ignition impulse.

All car enthusiasts know that to ignite fuel, a spark is used on the spark plug, which ignites the fuel in the cylinder, and the voltage on the spark plug reaches a level of 20 kV. Old cars use classic ignition systems, which have serious drawbacks. It is about the modernization and refinement of these schemes that we will talk.

The capacitance in this design is charged from the reverse surge of the blocking generator, which is stable in amplitude. The amplitude of this emission is almost independent of the battery voltage and the crankshaft speed, and therefore the spark energy is always sufficient to ignite the fuel.

The ignition circuit produces a potential on the storage capacitor in the range of 270 - 330 Volts when the battery voltage drops to 7 volts. The maximum operating frequency is about 300 pulses per second. Current consumption is about two amperes.

The ignition circuit consists of a standby blocking oscillator on a bipolar transistor, a transformer, a pulse-forming circuit C3R5, a storage capacitor C1, a pulse generator on a thyristor.

At the initial moment of time, when contact S1 is closed, the transistor is locked, and capacitance C3 is discharged. When the contact opens, the capacitor will be charged along the circuit R5, R3.

The charge current pulse starts the blocking generator. The leading edge of the pulse from the secondary winding of the transformer triggers the KU202 thyristor, but since capacitance C1 was not previously charged, there is no spark at the output of the device. Over time, under the influence of the collector current of the transistor, the transformer core is saturated and therefore the blocking generator will again be in standby mode.

In this case, a voltage surge is formed at the collector junction, which is transformed into the third winding and charges capacitance C1 through the diode.

When the breaker is opened again, the same algorithm occurs in the device, with the only difference being that the thyristor, opened by the leading edge of the pulse, will connect the already charged capacitance to the primary winding of the coil. The discharge current of capacitor C1 induces a high-voltage pulse in the secondary winding.

Diode V5 protects the base junction of the transistor. The zener diode protects V6 from breakdown if the unit is turned on without a bobbin or without a spark plug. The design is insensitive to the rattling of the contact plates of breaker S1.

The transformer is made by hand using a magnetic circuit ШЛ16Х25. The primary winding contains 60 turns of PEV-2 1.2 wire, the secondary winding contains 60 turns of PEV-2 0.31, the third winding contains 360 turns of PEV-2 0.31.

The spark power in this design depends on the temperature of the bipolar transistor VT2, which decreases on a hot engine, and vice versa on a cold engine, thereby significantly facilitating starting. At the moment the breaker contacts open and close, the pulse follows through capacitor C1, briefly unlocking both transistors. When VT2 is locked, a spark appears.

Capacitance C2 smoothes out the pulse peak. Resistances R6 and R5 limit the maximum voltage at the collector junction VT2. When the contacts are open, both transistors are closed; when the contacts are closed for a long time, the current flowing through capacitor C1 gradually decreases. The transistors close smoothly, protecting the ignition coil from overheating. The value of resistor R6 is selected for a specific coil (in the diagram it is shown for coil B115), for B116 R6 = 11 kOhm.

As you can see in the picture above, the printed circuit board is installed on top of the radiator. Bipolar transistor VT2 is installed on the radiator through thermal paste and a dielectric gasket.

This design allows the formation of a spark with a long duration, so the process of fuel combustion in the car becomes optimal.

The ignition circuit consists of a Schmitt trigger on transistors V1 and V2, decoupling amplifiers V3, V4 and an electronic transistor switch V5, which switches the current in the primary winding of the ignition coil.

The Schmitt trigger generates switching pulses with a steep rise and fall when the breaker contacts are closed or opened. Therefore, in the primary winding of the ignition coil, the current interruption speed increases and the amplitude of the high-voltage voltage at the output of the secondary winding increases.

As a result, the conditions for spark formation in the spark plug are improved, which contributes to the process of improving the starting of a car engine and more complete combustion of the combustible mixture.

Transistors VI, V2, V3 - KT312V, V4 - KT608, V5 - KT809A. Capacity C2 - with an operating voltage of at least 400 V. Coil type B 115, used in passenger cars.

I made the printed circuit board in accordance with the drawing according to.

In this system, the energy spent on sparking is accumulated in the magnetic field of the ignition coil. The system can be mounted on any carburetor engine with a +12 V vehicle on-board power supply. The device consists of a transistor switch built on a powerful germanium transistor, a zener diode, resistors R1 and R2, separate additional resistances R3 and R4, a two-winding ignition coil and breaker contacts.

The powerful germanium transistor T1 operates in switching mode with a load in the collector circuit, which is the primary winding of the ignition coil. When the ignition switch is turned on and the breaker contacts are open, the transistor is locked, since the current in the base circuit tends to zero.

When the breaker contacts are closed, a current of 0.5-0.7 A begins to flow in the base circuit of the germanium transistor, set by resistance R1, R2. When the transistor is completely unlocked, its internal resistance decreases sharply, and a current flows through the primary circuit of the coil, increasing exponentially. The process of current increase is practically no different from the similar process of a classical ignition system.

The next time the breaker contacts open, the movement of the base current slows down and the transistor closes, which leads to a sharp drop in the current rating through the primary winding. A high voltage U 2max is generated in the secondary winding of the ignition coil, which is supplied to the spark plug through the distributor. Then the process is repeated.

in parallel with the appearance of high voltage on the secondary winding, a self-induction emf is induced in the primary winding of the coil, which is limited by the zener diode.

Resistance R1 prevents the base circuit of the transistor from breaking when the breaker contacts are open. Resistance R4 in the emitter circuit is a current feedback element, reducing switching time and improving the TCS of transistor T1. Resistance R3 (together with R4) limits the current flowing through the primary circuit of the ignition coil.

Car enthusiasts make electronic ignition units, as a rule, according to the classical scheme, consisting of a high voltage source, a storage capacitor and a thyristor switch. However, such devices have a number of significant disadvantages. The first of them is low efficiency. Since the charge of a storage capacitor can be likened to the charge of a capacitor through a resistor, the efficiency of the charging circuit does not exceed 50%. This means that approximately half of the power consumed by the converter will be released in the form of heat on the transistors. Therefore, they require additional heat sinks.

The second disadvantage is that during the discharge of the capacitor, the thyristor short-circuits the output of the converter and the oscillations it produces are disrupted.

After the storage capacitor is discharged, the thyristor closes, and the capacitor again begins to charge with a smoothly increasing voltage from the Converter, from zero to the maximum value. At high engine speeds, this voltage may not reach the nominal value and the capacitor will not be fully charged. This leads to the fact that as the speed increases, the spark energy decreases.

The next drawback is explained by the lack of stability of the sparking energy when the supply voltage changes. When starting the engine using the starter, the battery voltage can drop significantly (up to 9-8 V). In this case, the ignition unit produces a weak spark or does not work at all.

We offer a description of electronic ignition that does not have these disadvantages. The operation of the device is based on the principle of charging a storage capacitor from a stable amplitude reverse surge of a waiting blocking generator. The magnitude of this emission depends little on the voltage of the vehicle's on-board network and the speed of the engine crankshaft, and, therefore, the spark energy is almost always constant.

The device provides a potential level on the storage capacitor within 300 ± 30 V when the voltage on the battery changes from 7 to 15 V, maintaining operability in the temperature range -15 - +90°. The maximum operating frequency is 300 pulses/s. The current consumption at f = 200 pulses/s does not exceed 2 A.

The schematic diagram of electronic ignition (Fig. 1) consists of a standby blocking generator on transistor V6, transformer T1, a circuit for generating trigger pulses C3R5, storage capacitor C1, and an ignition pulse generator on thyristor V2.

In the initial state, when the contact plates of the breaker S1 are closed, the transistor V6 is closed, and the capacitor C3 is discharged. When the contact opens, it will be charged through the circuit R5, RЗ, base-emitter transition V6. The charging current pulse starts the blocking generator. The leading edge of the pulse from winding II of the transformer (lower terminal in the diagram) triggers thyristor V2, but since capacitor C1 was not previously charged, there will be no spark at the output of the device.

After the transformer core is saturated under the influence of the collector current V6, the blocking generator will return to standby mode. The resulting voltage surge on the collector V6, transforming in winding III, charges capacitor C1 through diode V3.

When the breaker is opened again, the same processes will occur in the device, with the only difference being that the thyristor V2, opened by the leading edge of the pulse, will connect the now charged capacitor to the primary winding of the ignition coil. The discharge current C1 induces a high-voltage pulse in the secondary winding of the bobbin.

The device is insensitive to the rattling of the contact plates of the breaker. The first time they are opened, transistor V6 will open and remain in this state until the transformer begins to saturate, regardless of the further position of the breaker.

Transformer T1 is made on a magnetic core ШЛ16Х25 with a gap of about 50 μm. Winding I contains 60 turns of wire PEV-2 1.2, II - 60 turns PEV-2 0.31, III - 360 turns PEV-2 0.31. The transformer core can also be made of W-shaped iron. However, due to uneven cutting of the plates, the gap, even without a gasket, may be large. In this case, it is necessary to grind the irregularities at the junction of the magnetic circuit.

The KT805A transistor can be replaced with a KT805B, but due to the higher saturation voltage, slightly more power will be dissipated on it, which can lead to self-starting of the blocking oscillator at high temperatures. Therefore, it is advisable to install the KT805B transistor on an additional heat sink with an area of ​​20-30 cm 2.

Instead of diodes D226B, you can use KD105B - ​​KD105G, KD202K - KD202N (V1, V3), D223 (V4).

C1 is made up of two parallel-connected MBGO-1 capacitors of 0.5 μF each for a voltage of 500 V. C2 and C3 are MBM.

Thyristor KU202N can be replaced with KU202M or KU201I, KU201L. Since the KU201 direct voltage does not exceed 300 V, the voltage on the storage capacitor is reduced to 210 - 230 V by increasing its capacitance to 2 μF. Moreover, this does not have a noticeable effect on the spark energy.

To set up the device, you need an avometer and a breaker simulator - any electromagnetic relay powered from a sound generator. The relay can be connected via a step-down transformer to the lighting network. The frequency of the triggering pulses will then be equal to 100 pulses/s. With a diode connected in series, the trigger frequency will be 50 pulses/s.

If the parts are in good condition and the transformer leads are connected correctly, the device begins to work immediately. Check that the voltage on capacitor C1 is 300±30 V when the power supply changes within the above limits. The voltage should be measured with a peak voltmeter using the diagram shown in Figure 2.

The device is connected at the connection point of elements C1, V2, VЗ and, by changing the size of the gap in the transformer core, the required voltage value is achieved. If it is too low, the thickness of the gasket is increased. As the gap decreases, the voltage should drop.

When the ambient temperature is low, the spark energy may drop. In this case, it is necessary to reduce the value of the resistor RЗ, since at low supply voltage the thyristor V2 may not open.

The device was mounted using a printed method on a board measuring 95X35 mm, made of foil getinax or fiberglass (Fig. 3). The design of the electronic ignition unit is very different, depending on the available material and the installation location of the device.

V. BAKOMCHEV, Bugulma

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The advantages of electronic ignition in internal combustion engines are well known. At the same time, the currently widespread electronic ignition systems do not yet fully meet the complex of design and operational requirements. Systems with pulsed energy storage are complex, not always reliable and practically inaccessible to manufacture for most car enthusiasts. Simple systems with continuous energy storage do not provide stabilization of the stored energy [3], and when stabilization is achieved, they are almost as complex as pulsed systems.

It is not surprising, therefore, that Yu. Sverchkov’s article published in the magazine “Radio” aroused great interest among readers. A well-designed, extremely simple stabilized ignition unit can, without any exaggeration, serve as a good example of an optimal solution in the design of such devices.

The results of operating the unit according to Yu. Sverchkov’s scheme showed that, despite the overall fairly high quality of its operation and high reliability, it also has significant drawbacks. The main one is the short duration of the spark (no more than 280 μs) and, accordingly, its low energy (no more than 5 mJ).

This drawback, inherent in all capacitor ignition systems with one period of oscillation in the coil, leads to unstable operation of a cold engine, incomplete combustion of the rich mixture during warm-up, and difficulty starting a hot engine. In addition, the stability of the voltage on the primary winding of the ignition coil in the Yu. Sverchkov block is slightly lower than in the best pulse systems. When the supply voltage changes from 6 to 15 V, the primary voltage changes from 330 to 390 V (±8%), whereas in complex pulse systems this change does not exceed ±2%.

As the sparking frequency increases, the voltage on the primary winding of the ignition coil decreases. Thus, when the frequency changes from 20 to 200 Hz (the crankshaft speed is 600 and 6000 min -1, respectively), the voltage changes from 390 to 325 V, which is also slightly worse than in pulse units. However, this disadvantage can be

practically not to be taken into account, since at a frequency of 200 Hz the breakdown voltage of the spark gap of the spark plugs (due to residual ionization and other factors) is reduced by almost half.

The author of these lines, who has been experimenting with various electronic ignition systems for more than 10 years, set the task of improving the energy characteristics of the Yu. Sverchkov block, while maintaining the simplicity of the design. Solving it turned out to be possible thanks to the internal reserves of the unit, since the energy of the drive was only half used in it.

This goal was achieved by introducing a mode of multi-period oscillatory discharge of the storage capacitor onto the ignition coil, leading to its almost complete discharge. The idea of ​​such a solution is not new, but it is rarely used. As a result, an improved electronic ignition unit has been developed with characteristics that not all pulse designs have.

With a sparking frequency in the range of 20...200 Hz, the unit provides a spark duration of at least 900 μs. The spark energy released in the spark plug with a gap of 0.9...1 mm is at least 12 mJ. The accuracy of maintaining energy in the storage capacitor when the supply voltage changes from 5.5 to 15 V and the sparking frequency is 20 Hz is no worse than ±5%. The remaining characteristics of the block have not changed.

It is significant that the increase in the duration of the spark discharge is achieved precisely by the long oscillatory process of discharging the storage capacitor. The spark in this case is a series of 7-9 independent discharges. Such an alternating spark discharge (frequency of about 3.5 kHz) promotes efficient combustion of the working mixture with minimal erosion of the spark plugs, which distinguishes it favorably from a simple extension of the aperiodic discharge of the storage device.

The block converter circuit (Fig. 1) has remained virtually unchanged. Only the transistor was replaced to slightly increase the power of the converter and ease the thermal regime. Elements that provided uncontrolled multi-spark operation were excluded. The energy switching circuits and the discharge control circuits of the storage capacitor SZ have been significantly changed. It is now discharged during three (and at a frequency below 20 Hz - and more) periods of natural oscillations of the circuit, consisting of the primary winding of the ignition coil and capacitor SZ. Elements C2, R3, R4, VD6 provide this mode.

Considering that the operation of the converter is described in detail in, we will consider only the process of oscillatory discharge of the capacitor SZ. When the contacts of the breaker open, capacitor C4, discharging through the control junction of the thyristor VS1, diode VD8 and resistors R7, R8, opens the thyristor, which connects the charged capacitor S3 to the primary winding of the ignition coil. The gradually increasing current through the winding at the end of the first quarter of the period has a maximum value, and the voltage on the capacitor SZ at this moment becomes equal to zero (Fig. 2).

All the energy of the capacitor (less thermal losses) is converted into the magnetic field of the ignition coil, which, trying to maintain the value and direction of the current, begins to recharge the capacitor SZ through an open thyristor. As a result, at the end of the second quarter of the period, the current and magnetic field of the ignition coil are equal to zero, the capacitor SZ is charged to 0.85 of the original (voltage) level in the opposite polarity. When the current stops and the polarity changes on the capacitor SZ, the thyristor VS1 closes, but the diode VDS opens. The next process of discharging the capacitor SZ begins through the primary winding of the ignition coil, the direction of the current through which changes to the opposite. At the end of the oscillation period (i.e., after approximately 280 μs), the SZ capacitor is charged in its original polarity to a voltage equal to 0.7 of the initial one. This voltage closes the VDS diode, breaking the discharge circuit.

In the considered time interval, the low resistance of the alternately opening elements VD5 and VS1 bypasses the circuit R3R4C2 connected in parallel with them, as a result of which the voltage at its ends is close to zero. At the end of the period, when the SCR and diode close, the voltage of the capacitor SZ (about 250 V) is applied to this circuit through the ignition coil. The voltage pulse removed from the resistor R3, passing through the diode VD6, opens the thyristor VS1 again, and all the processes described above are repeated.

This is followed by a third, and sometimes (at startup) a fourth discharge cycle. The process continues until capacitor C3, which loses about 50% of energy during each cycle, is almost completely discharged. As a result, the duration of the spark increases to 900...1200 μs, and its energy - to 12...16 mJ,

In Fig. Figure 2 shows an approximate view of the voltage oscillogram on the primary winding of the ignition coil. For comparison, the dashed line shows the same oscillogram of the Yu. Sverchkov block (the first periods of oscillations on both oscillograms coincide),

To increase the protection against bounce of the breaker contacts, the starting unit had to be slightly changed. The time constant of the charging circuit for capacitor C4 is increased to 4 ms by selecting the appropriate resistor R6; The discharge current of the capacitor (i.e., the triggering current of the thyristor), determined by the resistance of the circuit of resistors R7, R8, is also increased.

The electronic ignition unit was tested for three years on a Zhiguli car and has proven itself very well. The stability of the engine after start-up has sharply increased. Even in winter, at a temperature of about -30 ° C, starting the engine was easy; it was possible to start driving after warming up for 5 minutes. Interruptions in engine operation during the first minutes of driving, which were observed when using the Yu. Sverchkov block, stopped, and acceleration dynamics improved.

The T1 transformer uses an ShL16X8 magnetic core. A gap of 0.25 mm is provided by three pressed gaskets. Winding I contains 50 turns of wire PEV-2 0.55; II - 70 turns PEV-2 0.25; III - 450 turns PEV-2 0.14. In the last winding, one spacer of capacitor paper should be laid between all layers, and the entire winding should be separated from the rest with one or two layers of cable paper,

The finished transformer is coated 2-3 times with epoxy resin or filled with resin completely in a plastic or metal box. You should not use an W-shaped magnetic circuit, since, as experience shows, it is difficult to maintain a given gap throughout the entire thickness of the set, and also to avoid short-circuiting of the outer plates. Both of these factors, especially the second, sharply reduce the power of the charging pulse generator.

When setting up the generator part of the unit, you can use the recommendations of Yu. Sverchkov in.

Due to its high reliability, the unit can be connected without connector X1 (disconnecting the capacitor Cpr of the breaker is mandatory), which is intended for a possible emergency transition to battery ignition, but the initial setting of the ignition timing will be much more difficult. If you keep the X1 connector, the transition to battery ignition is very simple - instead of the block block, a contact block is inserted into the socket of the X1 connector, with contacts 2, 3 and 4 connected.

G.KARASEV, Leningrad

LITERATURE:
1. A. Sinelnikov. How do the blocks differ? - Behind the wheel. 1977, No. 10. p. 17,
2. A. Sinelnikov. Electronic ignition unit of increased reliability. Sat. “To help the radio amateur”, vol. 73.-- M.: DOSAAF USSR, p. 38.
3. A. Sinelnikov. Electronics in the car. - M.: Energy, 1976.
4. A. Sinelnikov. Automotive electronics. - M.: Radio and Communications, 1985.
5. Yu. Sverchkov. Stabilized multi-spark ignition unit. - Radio, 1982, No. 5. p. 27.
6. E. Litke. Capacitor ignition system. Sat. “To help the radio amateur”, issue 78.- M.: DOSAAF USSR, p. 35.

List of radioelements

2.3. Contactless ignition systems.

Option 1.

Over the many years that have passed since the release of the first modifications of the Whirlwinds, many electronic thyristor ignition systems have been developed, which involve the use of standard engine breakers or a flywheel magnetic system as an ignition timing sensor. In the latter version, a necessary condition was the demagnetization of part of the magnets.

However, breakers are obviously the weakest point in the ignition system and require careful adjustment of the gaps. On the other hand, demagnetization of magnets is not accessible to everyone and leads to a loss of power removed from the magneto generator coils.

Below we describe a very reliable circuit of a thyristor contactless system developed by V. Mikhailov. The circuit includes a storage capacitor and a magnetoelectric sensor installed on the outside of the flywheel. When the magnetic circuit of the sensor is closed by the bars mounted on the flywheel, a pulse appears in the sensor coil, synchronizing the operation of the thyristor ignition system.

Due to the fact that the closing bar is installed at a certain distance from the payoff, the initially adjusted system does not then require any maintenance during operation. The ignition timing in each cylinder can be set with much greater precision than in other systems (exactly through 180°), which contributes to a slight increase in engine power. In addition, the launch of the Whirlwind is improved, the engine operates stably at low speeds. The standard magneto is used to charge the battery.

Ignition circuit (Fig. 86) consists of a pulse generator made on thyristor D4 and capacitor C6, ignition coils KZ-1 and KZ-2, control pulse shaper - asymmetrical trigger T1, T2, emitter follower T3 and electronic switch T4.

The circuit is powered from a voltage converter (Fig. 87), which is a push-pull relaxation generator assembled on two transistors T5, T6 and a transformer Tr. The generated voltage is rectified using bridge D5-D8.

An asymmetrical trigger has two states: stable - in the absence of an external pulse and quasi-stable - when a negative pulse arrives from the sensor. In the absence of a signal, transistor T is closed, since the sensor resistance is significantly less than the resistance R 1 and transistor T 2 is open, since a voltage sufficient to fully turn on is supplied to its base from the collector of transistor T. Transistors T 3 and T 4 are closed when the trigger is in a stable state, since their bases are connected through resistors R 6 and R 8 with a positive bus.

When the closing bar passes by the magnetic sensor DM, two pulses are formed in its coil, the first is negative, and the second is positive (if the ends of the coil are changed, the order will be reversed).

A negative impulse “overturns” the trigger, transferring it to a quasi-stable state. When transistor T 2 is loaded, a rectangular pulse of negative polarity appears, which, through the emitter follower T 3, enters the base of transistor T 4 and opens it, resulting in the load R 10 a pulse of positive polarity is highlighted. This pulse opens thyristor D4 through capacitor C5. An open thyristor closes a circuit consisting of a capacitor C6, charged from a converter with a voltage of 300-320 V, and an ignition coil. A high voltage pulse occurs on the secondary winding of the ignition coil.

The initial negative bias (0.6-0.7 V), necessary for stable operation of the thyristor, is set to the control electrode of the thyristor with a resistor R 11 and DZ diode.

When the motor is running at full speed, the voltage coming from the sensor can reach a significant value, so a limiter is installed at the input (resistor K.2 and zener diode D1). Capacitor C2 smoothes out voltage surges and prevents the trigger from overturning due to random noise. Zener diode D2 and resistor K9 stabilize the supply voltage of the trigger and emitter follower at a level of 9.5-10 V.

The amplitude of the sensor pulses can be adjusted by the size of the gap between the sensor and the closing strip. The gap size must be such as to ensure reliable engine starting. A voltage of 300 V to charge capacitor C6 is obtained in an electronic converter (Fig. 87).

The standard ignition of the Whirlwind engine is two-channel, i.e. each cylinder has a separate system. In the described scheme, a single-channel system is used: sparks are formed simultaneously in both cylinders - both in which the power stroke is performed and in which purging occurs, but since at the moment of purging the spark plug is washed by exhaust gases with only a small admixture of fresh mixture, ignition occurs in this cylinder not happening. The use of a single-channel circuit allows one to significantly simplify the system.

The pulse generator and control signal shaper are assembled in one block on two printed circuit boards connected by aluminum channels 35 mm high. Thyristor D4 and triode T4 are installed on one channel, and storage capacitor C6 is installed on the other. A trigger and an emitter follower are mounted on a small board measuring 80 x 90; on a large board measuring 80 x 165 there are thyristor control circuits and circuits connecting the unit to the motor and power source. The thyristor is insulated from the channel by a textolite bushing and a mica plate.

The block is attached to a textolite strip 80 x 70 with 11 terminals (M6 bolts), connected to the engine crankcase with a duralumin plate. Slightly spaced standard high-voltage transformers are also attached to the same plate. The general diagram for connecting the ignition units is shown in rice. 88.

In a magnetoelectric sensor (Fig. 89) A coil from the RSM relay is used, which has 5000 turns of PE 0.06 wire and a resistance of 750 Ohms.

The magnetic system is assembled from magnets from micromotors used in children's toys. To manufacture the sensor, two magnets from one micromotor are required. The coil is attached to the top bar 6 with a countersunk screw. Both magnets 5 are installed (with the same poles in the same direction) between the upper and lower 3 strips, tightened with screws and brass posts 4. The screws must be short so that the magnetic flux does not short-circuit through them. A getinaks board with a printed circuit in the form of two strips is installed on the top of the sensor, to one end of which the coil leads are soldered, and to the other - wires connecting the sensor to the circuit. Details of the sensor and contactor are shown on rice. 90.

The sensor is mounted on a plate attached to the base of the magneto on the outside of the flywheel. The mounting point for the strip is located between the protrusion of the magneto base for attaching the left capacitor and the protrusion on which the left contact of the breaker is located.

More precisely, the sensor itself is installed on the bar as follows. The throttle handle is turned to the “full throttle” position, which corresponds to the maximum ignition advance. The piston of the upper cylinder stops 7 mm from TDC. In this case, the sensor should stand opposite the second (in the direction of travel) free hole for attaching the magnet shoes in the flywheel. The contactor 9 is inserted into this hole. The second contactor for the lower cylinder is inserted into the free hole of the flywheel, shifted by 180°.

The axes of the holes in the flywheel are parallel to the diameter and located at a distance of 16 mm from it, so it is necessary to mill a plane on the flywheel with an end mill, and after installing the contactors in the holes, grind them on a cylindrical grinder.

Transducer block (Fig. 91) assembled on an aluminum plate measuring 120 x 110x3.

Diodes and resistors are mounted on a printed circuit board mounted above the base. Triodes (old designations - P213, P214, P216, P217) are mounted on an aluminum channel 35 mm high isolated from the base.

The transformer core Tr can be of any design; in this case it is made toroidal with dimensions 56 x 40 x 12 from E-310 steel. A step-up winding is first wound on it III (1250 turns of PESHO 0.25 wire), then the primary in two wires at once I (2 x 45 turns PEV 1.0) and secondary II (2 x 13 turns PEV 0.3).

Diodes D5-D7 type D226B must have a reverse current of no more than 10 μA at a reverse voltage of 600 V. If such diodes cannot be found, you need to put two diodes in series in each arm of the rectifier bridge, shunting them with 75 kOhm resistors.

The converter unit is installed in the engine compartment of the boat and is connected to the motor and to the boat's power supply circuit using 7- and 4-pin connectors.

The 12-volt battery (capacity 14 Ah) of the power supply system is charged from the coils of the standard magneto through a rectifier bridge using D242 diodes. To ensure the required charging current, a second coil is placed on the base of the magneto, which, when charging the battery, is connected in series with the standard coil. If, besides the ignition system, there are no other consumers of electricity on the boat, you can limit yourself to one coil. Modern motors provide for the installation of a standard rectifier bridge, which can also be used on motors of previous years of production.

The design of the electronic ignition allows you to switch to the standard system within 10 minutes. For this purpose, breakers are stored on the magneto board - when installing the electronic system, the contacts of the breakers are moved apart using insulating spacers.

To switch to standard ignition, it is enough to remove the electronic ignition unit from the engine on the textolite board, connect terminals 1 and 2 with jumpers to terminal 5, and 3 and 4 to terminal 8, turn off the power to the converter and remove the insulating gaskets from the breakers. The second magneto coil automatically switches to power the boat.

The ignition system does not require any special adjustment. When manufacturing a system, it is necessary to select transistors T1, T2, T3 with a current gain of 45-50. Resistance R .1 is selected so that the voltage at the base of transistor T1 is equal to 0.25 V in a steady state of the trigger, and the value of resistor K4 should be such that in a steady state transistor T4 is open. If the converter does not start (there is no voltage of 300 V), you need to check the correct connection of the transformer windings. The beginnings of the windings are indicated by dots in the diagram.

The KU201L thyristor must be selected with a switching voltage of at least 400 V. When adjusting the gap between the contactor and the sensor, thick paper with a thickness of 0.3-0.35 mm is laid between them. After the sensor is pressed and secured, the paper is removed.

Before installation on the engine, the assembled ignition system can be checked. To simulate trigger pulses, a circuit is assembled (Fig. 92), the output of which is connected to the ignition unit instead of a magnetic sensor.

Voltage from a 220 V household network is supplied to the input of the circuit. Bright sparks should be formed in the spark gaps installed instead of candles, which occur at the frequency of the alternating current in the network, i.e. 50 times per second.

When using a sound generator, the ignition circuit can be tested in various modes.

If the ignition unit does not work, the cause may be an installation error or a mismatch in the parameters of the parts.

The power supplied to the ignition coil has also changed significantly. At a frequency of 20 Hz with a B-115 coil it reaches 50...52 mJ, and at 200 Hz - about 16 mJ. The limits of the supply voltage within which the unit is operational have also been expanded. Reliable sparking when starting the engine is ensured at an on-board voltage of 3.5 V, but the functionality of the unit is maintained even at 2.5 V. At maximum frequency, sparking is not impaired if the supply voltage reaches 6 V and the spark duration is not less than 0.5 ms.
These results were obtained mainly by changing the operating mode of the converter, especially the conditions of its excitation. These indicators, which, according to the author, are at the practical limit of possibilities when using only one transistor, are also ensured by the use of a ferrite magnetic core in the converter transformer.
As can be seen from the block diagram shown in Fig. 1, its main changes relate to the converter, i.e. generator of charging pulses feeding storage capacitor C2. The startup circuit of the converter has been simplified; it is made, as before, according to the circuit of a single-cycle stabilized blocking oscillator. The functions of starting and discharge diodes (VD3 and VD9, respectively, according to the previous scheme) are now performed by one zener diode VD1. This solution ensures more reliable starting of the generator after each sparking cycle by significantly increasing the initial bias at the emitter junction of transistor VT1. This did not, however, reduce the overall reliability of the unit, since the transistor mode did not exceed the permissible values ​​for any of the parameters.
The charging circuit for delay capacitor C1 has also been changed. Now, after charging the storage capacitor, it is charged through resistor R1 and zener diodes VD1 and VD3. Thus, two zener diodes are involved in stabilization, the total voltage of which, when they open, determines the voltage level on the storage capacitor C2. Some increase in voltage across this capacitor is compensated by a corresponding increase in the number of turns of the base winding and transformer. The average voltage level on the storage capacitor is reduced to 345...365 V, which increases the overall reliability of the unit and at the same time provides the required spark power.
In the discharge circuit of capacitor C1, a stabistor VD2 is used, which makes it possible to obtain the same degree of overcompensation when the on-board voltage decreases, as three or four conventional series diodes. When this capacitor is discharged, the zener diode VD1 is open in the forward direction (similar to the diode VD9 of the original block). Capacitor C3 provides an increase in the duration and power of the pulse that opens the thyristor VS1. This is especially necessary at a high sparking frequency, when the average voltage level on capacitor C2 is significantly reduced.
In electronic ignition units with multiple discharge of a storage capacitor onto the ignition coil, the duration of the spark and, to a certain extent, its power determines the quality of the SCR, since all oscillation periods, except the first, are created and supported only by the energy of the storage device. The less energy is spent on each activation of the SCR, the greater the number of starts will be possible and the greater the amount of energy (and over a longer period of time) will be transferred to the ignition coil. It is therefore highly desirable to select a thyristor with a minimum opening current.
A thyristor can be considered good if the unit ensures the onset of spark formation (with a frequency of 1...2 Hz) when the unit is powered with a voltage of 3 V. Operation at a voltage of 4...5 V corresponds to satisfactory quality. With a good thyristor, the duration of the spark is 1.3. ..1.5 ms, if bad - decreases to 1... 1.2 ms.
In this case, strange as it may seem, the spark power in both cases will be approximately the same due to the limited power of the converter. In the case of a longer duration, the storage capacitor is discharged almost completely, the initial (also known as average) voltage level on the capacitor, set by the converter, is slightly lower than in the case of a shorter duration. With a shorter duration, the initial level is higher, but the residual voltage level on the capacitor is also high due to its incomplete discharge.

Thus, the difference between the initial and final voltage levels on the storage device in both cases is almost the same, and the amount of energy introduced into the ignition coil depends on it. And yet, with a longer spark duration, better afterburning of the combustible mixture in the engine cylinders is achieved, i.e. its efficiency increases.
During normal operation of the unit, the formation of each spark corresponds to 4.5 periods of oscillation in the ignition coil. This means that the spark represents nine alternating discharges in the spark plug, continuously following one after another.
Therefore, we cannot agree with the opinion (stated in) that the contribution of the third and, especially, fourth periods of oscillations cannot be detected under any conditions. In fact, each period makes its own very specific and tangible contribution to the overall energy of the spark, which is confirmed by other publications, for example. However, if the on-board voltage source is connected in series with the circuit elements (i.e. in series with the ignition coil and the accumulator), the strong attenuation introduced by the source and not by other elements does not really allow the above-mentioned contribution to be detected. This inclusion is exactly what is used in .
In the described block, the onboard voltage source does not take part in the oscillatory process and, naturally, does not introduce the mentioned losses.
One of the most critical units of the block is transformer T1. Its magnetic core Ш15х12 is made of oxyfer NM2000. Winding I contains 52 turns of wire PEV-2 0.8; II - 90 turns of wire PEV-2 0.25; III - 450 turns of wire PEV-2 0.25.
The gap between the Ш-shaped parts of the magnetic circuit must be maintained with the greatest possible accuracy. To do this, during assembly, a getinax (or textolite) gasket with a thickness of 1.2+-0.05 mm is placed between its outer rods, without glue, after which the parts of the magnetic circuit are pulled together with strong threads.
The outside of the transformer must be coated with several layers of epoxy resin, nitro glue or nitro enamel.
The reel can be made on a rectangular spool without cheeks. Winding III is wound first, in which each layer is separated from the next by a thin insulating spacer, and completed with a three-layer spacer. Next, winding II is wound. Winding I is separated from the previous one by two layers of insulation. The outer turns of each layer when winding on a spool should be fixed with any nitro glue.
It is best to arrange the flexible coil leads after all winding has been completed. The ends of windings I and II should be brought out in the direction diametrically opposite to the ends of winding III, but all leads should be at one of the ends of the coil. The flexible leads are arranged in the same order, which are secured with threads and glue on a gasket made of electrical cardboard (pressboard). Before pouring, the leads are marked.
In addition to KU202N, the unit can use the KU221 thyristor with letter indices A-G. When choosing a thyristor, it should be taken into account that, as experience shows, KU202N compared to KU221 in most cases have a lower opening current, but are more critical to the parameters of the trigger pulse (duration and frequency). Therefore, for the case of using a SCR from the KU221 series, the ratings of the elements of the spark extension circuit must be adjusted - capacitor C3 should have a capacitance of 0.25 μF, and resistor R4 should have a resistance of 620 Ohms.
The KT837 transistor can have any letter indices, except Zh, I, K, T, U, F. It is desirable that the static current transfer coefficient is not less than 40. The use of a transistor of another type is undesirable. The transistor heat sink must have a usable area of ​​at least 250 sq.cm. It is convenient to use a metal casing of the block or its base as a heat sink, which should be supplemented with cooling fins. The casing must also provide splash protection for the unit.
Zener diode VD3 must also be installed on the heat sink. In the block it consists of two strips measuring 60x25x2 mm, bent in a U-shape and nested one inside the other. The D817B zener diode can be replaced with a series circuit of two D816V zener diodes; with an on-board voltage of 14 V and a sparking frequency of 20 Hz, this pair should provide a voltage of 350...360V to the drives. Each of them is installed on a small heat sink. Zener diodes are selected only after selecting and installing the thyristor.
The VD1 zener diode does not require selection, but it must be in a metal case. To increase the overall reliability of the unit, it is advisable to equip this zener diode with a small heat sink in the form of a crimp made from a strip of thin duralumin.
The KS119A stabistor (VD2) can be replaced with three D223A diodes (or other silicon diodes with a pulsed forward current of at least 0.5 A) connected in series.
Most of the block parts are mounted on a printed circuit board made of foil fiberglass laminate 1.5 mm thick. The board drawing is shown in Fig. 2. The board is designed taking into account the possibility of mounting parts for various replacement options.

For a unit intended to operate in areas with harsh winter climates, it is advisable to use a tantalum oxide capacitor C1 with an operating voltage of at least 10 V. It is installed instead of a large jumper on the board, with the connection points for the aluminum oxide capacitor (it is shown on the board) , suitable for operation in the vast majority of climatic zones, should be closed with a jumper of appropriate length. Capacitor S2-MBGO, MBGCH or K73-17 for voltage 400...600 V.
If you select a thyristor block from the KU221 series, the lower part of the board in Fig. 2 must be adjusted as shown in Fig. 3. When installing the SCR, it is necessary to isolate one of the screws for its fastening from the printed circuit of the common wire.
The performance check, and even more so the adjustment, should be carried out with exactly the ignition coil with which the unit will work in the future. It should be borne in mind that turning on the unit without an ignition coil loaded with a spark plug is completely unacceptable. To check, it is enough to measure the voltage on storage capacitor C2 with a peak voltmeter. An avometer with a constant voltage limit of 500 V can serve as such a voltmeter. The avometer is connected to capacitor C2 through a D226B diode (or similar), and the avometer terminals are shunted with a capacitor with a capacity of 0.1...0.5 μF for a voltage of 400...600 V .
At a rated supply voltage (14 V) and a sparking frequency of 20 Hz, the voltage on the drive should be in the range of 345...365 V. If the voltage is less, then first of all select a thyristor taking into account the above. If, after selection, sparking is ensured when the supply voltage drops to 3 V, but there is an increased voltage on capacitor C2 at the rated supply voltage, you should select a zener diode VD3 with a slightly lower stabilization voltage.
Next, the unit is checked at the highest sparking frequency (200 Hz), maintaining the rated on-board voltage. The voltage on capacitor C2 should be within 185...200 V, and the current consumed by the unit after continuous operation for 15...20 minutes should not exceed 2.2 A. If the transistor heats up above 60°C during this time at room ambient temperature, the heat-dissipating surface should be slightly increased. Capacitor C3 and resistor R4, as a rule, do not require selection. However, for individual instances of SCRs (of both types) it may be necessary to adjust the ratings if instability in sparking is detected at a frequency of 200 Hz. It usually manifests itself in the form of a short-term failure in the readings of the voltmeter connected to the drive, and is clearly noticeable by ear.
In this case, you should increase the capacitance of capacitor C3 by 0.1...0.2 μF, and if this does not help, return to the previous value and increase the resistance of resistor R4 by 100...200 Ohms. One of these measures, or sometimes both together, usually eliminates the launch instability. Note that increasing the resistance reduces and increasing the capacitance increases the duration of the spark.
If it is possible to use an oscilloscope, then it is useful to verify the normal course of the oscillatory process in the ignition coil and its actual duration. Before complete attenuation, 9-11 half-waves should be clearly distinguishable, the total duration of which should be equal to 1.3...1.5 ms at any sparking frequency. The X input of the oscilloscope should be connected to the common point of the ignition coil windings.
A typical waveform is shown in Fig. 4. Bursts in the middle of the negative half-waves correspond to single pulses of the blocking generator when the direction of the current in the ignition coil changes.
It is also advisable to check the dependence of the voltage on the storage capacitor on the on-board voltage. Its appearance should not differ noticeably from that shown in Fig. 5.
It is recommended to install the manufactured block in the engine compartment in the front, cooler part. The spark suppression capacitor of the breaker should be disconnected and its output should be connected to the corresponding contact of the socket of connector X1. The transition to classic ignition is carried out, as in the previous design, by installing the X1.3 contactor insert.
In conclusion, we note that attempts to obtain an equally “long” spark with a transformer on a steel magnetic core, even from the highest quality steel, will not lead to success. The longest duration that can be achieved is 0.8...0.85 ms. Nevertheless, the block, almost unchanged (the resistance of resistor R1 should be reduced to 6...8 Ohms), is also operational with a transformer on a steel magnetic core with the specified winding characteristics, and the performance of the block is higher than that of its prototype.