Every motorist wants more control over the state of the system power supply in the car. And reload, and nagasarete battery have a negative impact on her health, reducing the already short period of time service energy storage. Ensuring optimal operating conditions the battery of accumulators in the paper.

Element performance monitoring system battery-generator-regulator (the on-Board voltage regulator), as a rule, serves as a relay charge. Operating experience the classic "Lada" shows that it is possible to improve the information content of the warning lamps, replacing them with standard relays his RS the electronic version.

Analysis of control devices, published in the magazine "Radio" the last 75 years, did not reveal option that is appropriate in all respects. Still the best is this, which is available on the dashboard warning light in addition to the lack of charging points and redundant the voltage in the electrical system

We offer our readers the device differs from the known full design and electrical interchangeability with relay RS, fast Assembly and disassembly. It implements a mixed principle of state control the vehicle network. The absence or presence of charge of the battery is determined not by voltage level, and the absence or presence of charging current. So operates and relay RS.

This principle gives certain advantages: provides simplicity and reliability the device, no need for defining and setting the threshold response is almost independent of temperature, which is important for the measuring nodes. Monitoring over-voltage - traditional, by means of the sensor maximum voltage (DMN).

Relay charge control can be functionally divided into the following parts (see circuit diagram): current sensor charge amplifier with voltage - R1-R3, VT1; DMN - R5-R7, DA1; a pulse generator - C2, R8, DD1.1; the current amplifier - VT2; buffer-inverter - DD1.2-DD1.4.

Electronic control relay charging

With the closure of the contacts of the switch SA1 "Ignition on" (engine running or not operates at low speed), the transistor VT1 is closed, as in his basic circuit flows is negligible reverse current diodes VD2, VD4, VD6 generator unit. Therefore, the voltage on the capacitor C1 and the lower scheme the input of the Schmitt trigger DD1.1 is practically zero.

DMN is a voltage comparator, performed on a managed the Zener diode DA1 (part no tl431ilp, domestic analogue KREN [1]). Zener diode closed because the control output voltage taken from the divider R5R6, less internal model (it is equal to 2.5).

Therefore, the capacitor C2 through a blocking diode VD1 devices charged almost to the supply voltage. The pulse generator is inhibited, and at its output high level. The output buffer DD1.2-DD1.4 low level, the transistor VT2 is open and saturated Illuminates the warning light HL1, indicating the absence of charging current of the battery.

By increasing the frequency of rotation of the crankshaft of the motor voltage, produced by the generator G1 of the car increases. As soon as it exceeds the voltage on the battery, open the three-phase diode bridge VD1- VD6 generator block. You receive the pulsating current in the base circuit of the transistor VT1. As a consequence, its collector is formed by pulse the sequence with variable duty cycle. An integrating capacitor C1 allocates a fixed component. As soon as its value exceeds approximately two-thirds of the supply voltage of the IC, Schmitt trigger DD1.1 switches to opposite condition. As a result, the transistor VT2 is closed and the lamp HL1 off.

Note that according to the logic of the work described in both modes the device is no different from the relay RS.

Work in the third mode depends on the voltage level of the on-Board network. If car has the temperature-compensated stabilizer, similar to [2, 3], the upper limit can be taken equal to 15.5... 16 V. When using conventional relay-regulator (stabilizer) 121.3702 the specified threshold can decrease to 14.5...15 V.

Upon reaching the selected threshold is triggered DMN and the voltage at the anode blocking diode VD1 is reduced to approximately 2 V. the Charged capacitor C2 closes the diode VD1, removing the lock from the pulse generator.

The capacitor C2 begins to discharge through the resistor R8 and the output of the Schmitt trigger DD1.1. As soon as the capacitor voltage, decreasing, reaches a third supply voltage of the chip, the trigger DD1.1 switches and its output appears a high level. The capacitor again begins to charge through resistor R8 from the output of trigger generator will begin to produce rectangular pulses.

As a result, the transistor VT2 will be periodically opened and closed, lamp HL1 will flash, signaling the violation in the electrical equipment, exceed the vehicle voltage. The use of chips with the Schmitt trigger due to their good noise immunity because "hysteretic characteristics.

Elements HL2, R11 form a duplicate indicator. It is not mandatory, but will help out at burnout of the lamp HL1.

In the relay instead CTA can run any of a silicon p-n-p transistor, and instead CTA - any silicon compound of the structure p-n-p with the allowable current collector not less than 2A. Chip CRT it is desirable not to change to other due to its greater load capacity. When the chip selection should DA1 keep in mind that the working temperature range of the Zener diode part no tl431ilp (and its varieties relating to industrial standard) - 40 to +80 °C; the domestic counterpart CRAN - -10 to +70 °C.

The relay is assembled on the circuit Board dimensions 47x29 mm from the PCB or Micarta thickness of 1 mm. Connections are made by wire MGTF section of 0.07 mm2, and most high-current - 0,35 mm2. The fee attached to the relay card laminated bakelite RS through two plastic bushings.

To install an electronic analog must be flared metal casing relay, remove from the Executive Board of electromagnetic relays, shorten to 3...5 mm conclusion 87. Conclusions 30/51, 85 and 87 to solder the flexible conductors. Common wire an electronic analog relays to connect with metal casing to ensure contact when mounted to the vehicle housing. After installing the Board into the casing again to zavaltsevat its perimeter.

To test the functionality of the relay required adjustable DC voltage from 10 to 16 V with an output current up to 1.5 A. the Positive output source connected to the output 87, sub-zero is a common wire. To the conclusion 30/51 connect indicator automotive lamp A-3.

Changing the supply voltage from 10 to 14, the control light is switched on. Connect the output 85 through resistor 51...100 Ohm to GND - the lamp should turn off. Then slowly increase the supply voltage and see switching on and off of the lamp. "Hysteresis threshold voltage usually does not exceed 20 mV.

Like checking the operability of the relay on the car. Include the ignition - the indicator light on side flap is activated and illuminates continuously. Start the engine and idle mark off the lamp.

Short between conductors that are appropriate to the terminals 15 and 67 of switch controller, after removing them from the pins. Gently increase the engine speed, and depending on the load side of the network control pulse lamp operation mode with a frequency of several Hertz (it depends on the component values R8, C2).


  • An integrated circuit. Circuits for linear power supplies and their use (Handbook). - M: Dodeka, 2001.
  • Biryukov, S. a Simple temperature-compensated voltage regulator. Radio, 1994, No. 1, p. 34, 35.
  • Lomanovich V. Thermocompensation regulator voltage. Radio, 1985, No. 5, pp. 24-27.
  • Author: V. Khromov, Krasnoyarsk

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