It is known that a large portion of the Russian fleet is equipped with a simple contact ignition systems, based on the principle of interruption of the current flowing through the low voltage winding high voltage transformer, which is the ignition coil, using a mechanical chopper, which represents a contact switch, driven from the shaft of the ignition distributor.
This system has many shortcomings, the current flowing through the primary winding of the ignition coil is too high, resulting in the breaker arcing occurs, inevitably leading to burning and melting his contacts, plus, in winter or autumn-spring time is added electrochemical erosion of the contacts. But that's not all, the duration of the spark discharge, as a result of high current flowing through the breaker contacts get a small, 0.3 to 0.8 mS, and result in poor ignition of the combustible mixture, requires more rich, poor acceleration of the engine at low revs, higher fuel consumption. All these deficiencies have long been known, and has since appeared as a powerful high-voltage transistors, the automotive industry is gradually moving equipment on new cars contactless electronic ignition systems that use contactless ignition sensor, electronic switch with a powerful high-voltage transistor on the output, as well as more powerful ignition coil with low resistance windings.
To improve the performance of the car with contact ignition system by setting contactless system from a newer modification of this brand. But this method is relatively expensive - requires a complete replacement of all elements of the ignition system, including sensor-distributor, ignition coil, and the acquisition of the corresponding electronic switch. Moreover, not every model old model, you can select suitable elements from the newer models. However, significantly improve the quality ignition simple contact system, if contact between circuit breaker and staff ignition coil include simple transistor switch, the output stage designed for high-voltage high-power transistor. In this win, compared to a simple system will be for several positions :
first, it will decrease the current through the breaker contacts and they will cease to burn and to correlate, secondly, the duration of the spark discharge will increase about two times that will lead to improved ignition of the mixture, thirdly, in case of failure of the transistor switch can be a simple permutation of the wire to bring the system back to the original version.
Schematic diagram of the switch shown in the figure. Practically, this is a simplified version of the switch "131.3734" from the contactless ignition system of the car "Volga".
When the closed breaker contacts to the base of transistor VT1 relative to the emitter receives a negative voltage and the transistor opens. The opening leads to the fact that through this transistor and R4 to the base of power transistor VT2 positive voltage is supplied, and it opens. The current through it is supplied to the primary winding of the ignition coil L1. Upon opening the breaker contacts receipt voltage VT1 base ends and it is closed, and in a trail behind him closes and VT2. In the coil, the circuit consisting of the primary winding L1 and the capacitor C2, vibrations may occur that induce a high voltage pulse in the secondary winding L1. This high voltage pulse through the distributor to the candle and spark discharge occurs. The duration of the sparks in the air, from the beginning of the capacitive to the end of his inductive phase, is about 2 mS, which is more than twice the duration of the spark classic ignition system.
The resistor R1 is not first sight is not needed, but in practice, when passing through the breaker contacts too low current, do not necessarily reliable electrical contact, and possible omissions in the operation of the ignition system. To avoid this introduces the resistor R1, which creates the necessary minimum current through these contacts.
Transistor CTA can be replaced by CT, and the transistor CTA on CTA.
The switch is going to surround mounted in the casing faulty switch from a contactless ignition system of the car "Volga" or "UAZ".
Setup is selecting a value R4 (at least 22) and R2 (at least 300) so that when connected to the ignition coil and the closed breaker contacts, the voltage at the collector VT2 was minimal (no more than 1.5 In). Thus the current through the coil is maximum.
Subjectively, with this switch, the car moves better at low revs, better moves at idle.
To increase the energy of the sparks, if you install the ignition coil with low resistance windings of the car VAZ-08-099, but will need to refrain from for a long period of switching on the ignition with the engine off, since the current through the coil will be high and may damage the output transistor of the switch.
Author: Kazakov, A. T.; Publication: N. Bolshakov, rf.atnn.ru