ELECTRONIC IGNITION:OPTIONS | MODEL CONSTRUCTION

We are talking about different versions of electronic ignition devices (UEZ), is made as transistors and IC. The lack of scarce elements, as well as the simplicity of the schemes allow you to collect the block of electronic ignition even ignorant in electronics motorists. UEZ can work together with the ignition coil B-117 (B-117A) and B-115V, used in cars “Zhiguli”, “Moskvich” and “Zaporozhets”, and since there is no special transformer to storage capacitor, the device consumes virtually no current when the ignition is on, has small weight and dimensions.

Consider first the work of the UEZ transistors (Fig. 1). When you turn the key in the ignition closes the contact pair ЅА2 and a 12 V battery CB1 is supplied to the electronic device and the ignition coil 1.1. When the PR circuit breaker is open, the battery current flows through the resistor R3 and the base of the transistor VT1. It will open and transistors VT2 and VТЗ will remain closed the current through the coil L1 does not flow. In this case, consumption of the ignition system current will be about 10mA, the value of which is determined by the resistance of the resistors R2, RZ and 1R5.

If the PR contact is closed, current flows about 40 mA. The battery voltage drops across the resistor R2, and transistor VT1 is locked. Circuit R5, C2, R6, and through the base of VT2, VТЗ current flows to charge the capacitor C2, the opening of these transistors. As a result, the current in the ignition coil increases to a value of 3.5 A.

As the charge of the capacitor C2 the voltage across it increases and the base current of transistors VT2, VТЗ gradually decreases.

When the engine is cranked, the breaker opens. Battery CB1 through resistors R2, RZ and the base of VT1 starts to leak current of approximately 2 mA. The VT1 transistor opens and the capacitor C2 is discharged through the circuit: VT1, VD2, V6.

During and after the discharge of the capacitor C2, the transistors VT2 and VТЗ remain locked, the current through the ignition coil is not leaking.

Simultaneously with the discharge of C2 is the charge from the battery through resistors R2, R1 and the diode VD1, capacitor C1. The elements R2, R1, R4, VD1 and VT1 base form a voltage divider, so the capacitor C1 does not exceed 5 V.

Subsequent contact closure OL transistor UT1 is locked immediately, as through a resistor K4 and the base of transistor begins to discharge the capacitor C1. The time of his discharge is selected so that the locking VT1 (unlock VТЗ) ahead of the regular time of opening the contact PR (lock VТЗ) for a period sufficient to increase the coil current to a value that ensures that by opening breaker a powerful spark in the spark plugs.

Fig. I. schematic diagram of the transistor option UEZ

Fig. I. schematic diagram of a transistor embodiment, the UEZ.

Fig. 2. Schematic diagram of the UEZ on the chip.

Fig. 3. Block design UEZ.

Fig. 4. Circuit Board UEZ in IMS.

R and p. 5. Wiring connection to UEZ ignition coils: 1 — B-117, 2 — B 115V

R and S. 5. Wiring connection to UEZ ignition coils: 1 — B-117, 2 — B-115V.

Fig. 6. A schematic diagram of a simplified version of UEZ transistors.

Fig. 7. The circuit Board is simplified UEZ.

The locking of the transistor VT1 causes the charge of capacitor C2 at circuit R5, C2, R6, VT2 base and VТЗ. However, due to the large time constant of this circuit C2 is charged slightly and flowing through VT2 base current is determined by the value of resistor R5 and Rб. When using VT2 starts to leak current, the transistor VТЗ open in the ignition coil begins to increase the current, which at the time of opening the contact PR reaches the value sufficient for the formation of a strong spark in the spark plugs.

The larger the capacitance of the capacitor C2, the easier the engine starts with crank.

When opening the contact pair OL the transistor VT1 is opened, and the transistors UT2 and VТЗ sharply locked, the current in the ignition coil is interrupted, its windings a voltage in excess of the same, produced in the conventional ignition system. Moreover, the energy accumulated by the coil, goes directly to the spark plugs, bypassing the capacitor C, connected in parallel to the circuit breaker and the resistance of the primary winding. The result is a heating of the ignition coil is significantly reduced.

With increasing engine speed, the period of the closed state of the breaker approaches the rise time of current in the ignition coil. At the same time reduced and the period of the open state of the contact pairs, leading to a decrease of energy stored by the capacitor C1, and thus to reduce the delay of unlocking of the transistor VТЗ.

The UEZ can be constructed using an integrated circuit (Fig. 2). Design the device is designed to work with ignition coil B-117,— in figure 3. All components and parts are fixed with screws on the panel size 100Х56 mm PCB sheet thickness of 2-3 mm. placed In the center of the printed circuit Board (Fig. 4), made of one-sided foil fiberglass with a thickness of 2-3 mm. is Connected as follows: pin 15 is connected to the base of the transistor VT1; 16 — petal 1; 17 — to the conclusion “1” switch ЅА1; 18 to terminal B; 19—to petal 2. Some of the elements that are not shown in figure 3, placed and connected as follows: a resistor R2 connected between a conclusion “1” switch ЅА1 and petal 1, resistor R6 between petals 1 and 2, the resistor R7 between 2 and 3; between the petals 6 and 7 of a jumper; the emitter of the transistor VT1 is connected to the petal 6, and its collector connects to pin “2” ЅА1, its output is “4” is connected to the petal 4, and the output

“3” — 5 petal. Switch ЅА1 attached to the bracket 9 and is raised above the Board 10 mm. the Sz Condenser is included between the lobes 2 and 6.

Insights UEZ for inclusion in the ignition system made of aluminium sheet of thickness 1 mm. at the same time they are used to attach the unit to the ignition coil. The conclusions of the “B” and “1” are fixed at the corresponding terminals of the ignition coil and “M” forms a clamp to it and tighten the screw.

Cover UEZ — plastic or metal, with a height of 30 mm. on the one hand it is fixed nut of the switch ЅА1, and on the other two long screws (posts) that are used for simultaneous fastening of the clamp “M”, petals 3 and 7. The shroud should cover the circuit Board and a few hung from it to protect the device from water or oil. For cooling the radiator of the transistor VT1 in the Board and in the upper part of the lateral side of the casing adjacent to the radiator from the output “PR”, drilled a few holes.

Electronic ignition is not critical to the possible location details, and its design can be

any. However, when mounting the UEZ note that the radiator of the transistor VT1, findings “B”, “PR” and “1” are energized, so they need to put on the vinyl chloride pipe.

Connecting to a switch SA1 and the emitter of the transistor VT7 petals, you can use wire of 0.5 mm2. Wiring diagrams UEZ to the ignition system of a car with coils B-117 and B-115 are shown in figure 5. The wire from B-115 V going to the starter relay, unplug it from the ignition coil.

The details of the UEZ. All resistors are of MLT type. The diode VD3 must have a valid reverse voltage of At least 350 V and direct current of at least 100mA. Capacitors C2 and NW — K53-1 with an operating voltage of 15 V. it is Possible to use a capacitor K53-4 and others, capable of operating at temperatures -40°C… +70°C. C1 — K53-1A, K53-4, better metalloboranes MBGP, MBGC.

As transistor VT2 can be used КТ503, КТВ15, and instead КТВ09А — КТ704А (IN). Instead of the R2 resistor it is better to install a lamp SM-37, which will allow to control the operation of the UEZ, breaker contacts, and will serve as an indicator for setting initial ignition timing. In addition to SM-37 you can use the switch the light bulb on 24 V with currents up to 100 mA.

Prior to the installation of the UEZ on the car, you should check it under current. For this to terminals “B” and “M” are connected with the correct polarity, the power source voltage of 6-12 V, and to the terminals “B” and “1” — a control lamp on 12 In with power not exceeding 5 watts. If there are no errors in the installation of it should not burn. Then, periodically closing between terminals “PR” and “M”, we see that for any position of the switch ЅА1 test lamp illuminates to the beat of a circuit these terminals.

Install ЅА1 switch to position “a”. Hold in a closed state of terminal “PR” and “M”, we see that the test lamp, flushing, begins relatively slow to fade. After that, the UEZ can be installed on the car. The engine will operate normally. If, however, with the increase in revs it does not, it indicates excessive air gap between the contact plates of the circuit breaker and it must be slightly reduced.

To ensure a long reliable operation desirable full scan UEZ. It is carried out in the following sequence:

1. Include ammeter DC at 5 amps to the circuit wire coming from ignition switch to terminal “B” of ignition coil (it must be connected and terminal “B” UEZ). БА1 switch is set to the “electronic ignition”.

2. Include ignition and be convinced that the ammeter will show the inrush current to about 3 And then decrease to 0.05—0.1 A (in the presence of leakage of the capacitor C2, this current can be larger than 0.1 A, but should not exceed 1.1 A). If the current subsides, then immediately turn the ignition off — UEZ faulty. When the inrush current is not, rotate the crankshaft a little (contact breaker could be disconnected). With a weak throwing current it is necessary to reduce the resistance of the resistor R6.

3. Start the engine and measure the current consumed by the ignition system. If the current exceeds 1.1 A, it save a slight increase of the gap of the contact system of the interrupter. Warm up the engine.

4. Increasing the engine speed, monitor the readings of the ammeter. The current may initially increase, but not to exceed 1.1 a, And then decrease to 0.6—0.7 A. If the current is less than 0.6 A, you should increase the resistance of the resistor 1?1 (22 to 27 n), despite the fact that the engine can stably run on all RPMs. In the operation of the UEZ no adjustment, is not required.

To use UEZ motorcycle recommended:

1. To reduce the resistances of the resistors twice, and resistor R5 to 1.5 kω.

2. Of capacitors to increase two times.

3. To measure the current flowing through the primary winding of the coil (transformer) ignition at high engine speeds in conventional ignition.

4. Install on the motorcycle UEZ and make him monitor and adjust similarly performed on the car. In this case you may need to change the capacitance of the capacitor C1.

Flowing from the ignition switch to the coil current must not exceed 1.1 A. When the power supply 6 can be used In the chip К149КТ1Б.

The transistor version of the UEZ is significantly simplified if to exclude from the scheme switch 5А1 and elements that provide delayed unlocking of the transistors UT2 and ERD. A schematic diagram of a simplified circuit Board of electronic ignition in figures 6 and 7.

The disadvantages of such a UEZ are the need to dismantle during the transition to normal ignition; a more loaded mode of operation of transistors, as well as the fact that the average current flowing through the ignition coil when the engine is running, almost the same as in the normal ignition. This does not exclude heating of the ignition coil. However, a minimum of parts, simplicity of construction and the independence of the device characteristics by the clearance between the contact plate of the interrupter still have a number of advantages of UEZ in front of the previous one.

B. TRUTNOV, Kharkov

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