Failures in the heating system of the car "Zaporozhets" are often associated with malfunction of the electromagnetic actuator of a gasoline pump having a contact switching current of the electromagnet. In operation, the pump current is interrupted by the contacts exceeds 5 A, which leads to wear of the contacts. The erosion of the contacts with the violation of their conductivity or, on the contrary, their "joining" lead to a stop of the fuel pump.
To increase the reliability of the pump is possible, having unloaded his contacts within the drive transistor current amplifier (see diagram). Coil Y1 electromagnet included in the emitter circuit transistor switch VT1, and the contacts commute its base current.
VD1 diode protects the transistor from breakdown voltage of self-induction with the winding of the electromagnet V1 in the closing moments of the transistor. The use of a transistor switch allows you to significantly reduce the current through the contacts and increase the reliability of the fuel pump.
The body of the transistor VT1 can be fastened directly to the parts that have a connection to the vehicle body, which increases the ease of installation. Instead of the transistor CTA you can use transistors series P-P.
Author: L. Mackinaw, POS; Publication: N. Bolshakov, rf.atnn.ru