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The proposed scheme (Fig. 1) is designed for installation on vehicles with contact ignition system.

It has the following advantages:

  • power sparks increased;
  • the breaker contacts do not burn;
  • don't need a resistor in the circuit of the ignition coil;
  • with the ignition on but not started the engine diagram smoothly, without sparks, are disabled.

Power sparks in this scheme depends on the temperature VT2, and decreases when the engine is hot, and the cold increases, thereby facilitating the start.

When closing and opening of the breaker contacts SKимпульс passes through C1, briefly opening VT1 and VT2. When closing VT2 generates a spark. C2 smoothes the pulse peak voltage. R6 and R5 limit the maximum voltage at the collector of VT2. Upon reaching the desired voltage VT2 is opened, limiting further increase in voltage.

The stress of opening VT2 depends on the magnitude of the Uбэ which, in turn, depends on temperature. When you open contacts of the breaker VT1 and VT2 are closed. In a long-closed contacts of the current through C1 is gradually decreasing, respectively, and VT1 and VT2 closes smoothly, protecting the coil from overheating.

Details: S1 - type km or K73. R6 provides stabilization of the output voltage. Its value is chosen for a specific ignition coil. In the diagram the value of R6 is indicated for the coil B. Its main parameters: Ri=1.6 Ω, I<8A, Ui<330 V. the transformation Ratio K=68. For coil B (Ri=0.6 Ohm, Ii<20 A, Ui<160, K=154) the value of R6=11 K. For this reel is better to use as transistors VT2 CTA.

To improve the reliability of the scheme it is better to use a composite transistor VT2, as shown in Fig.2.

Author: P. Bryantsev, Tyumen region, Uvat district, Ivanivka village; Publication: N. Bolshakov, rf.atnn.ru