Smooth turning off of the light in the car interior. Smooth on/off of interior lighting in a car Smooth on/off of interior lighting
This device is designed to smoothly dim the light in the car when the door is closed. A very useful thing, especially in the dark, when you need a little light when leaving the car.
The circuit diagram of the device is quite simple. If (circuit SA1) the switch is open, the light does not light up, due to the fact that transistors KT817 and KT361 (VT2 and VT1) are closed. Based on this, when the door is opened, these transistors will open and therefore the interior lighting will turn on.
It is recommended to place the transistor (KT817) on a heat sink, since heating occurs when the brightness of the light decreases. It is better to use a heat sink with an area of 4 to 6 cm2. Capacitor (C1) is used for the effect of smooth fading of light. Consequently, when the door is closed, the switch closes and the light continues to glow due to the remaining discharge of the capacitor.
This circuit is powered from the car's 12-volt network. You can also connect other devices in parallel, which will not interfere with each other. If you put this circuit on each car door, then when you open and close each of them, the light will also turn on and off smoothly.
Resistor (R3) serves for better lamp turn-off speed. In order to change the adjustment limit, the value of the resistor (R6) needs to be changed from 270 to 430 Ohms. The devices are located under the interior lampshade. For radio enthusiasts For car enthusiasts
Smooth turning off of the light in the car interior
Many foreign cars have a function for smoothly turning off the interior lights. I also wanted to have such convenience in my car. To do this, I assembled a device using two transistors, three resistors, one diode and an oxide capacitor. Its diagram is shown in Fig. 1.
At the moment the standard door limit switch SF1 of the car opens when the doors are closed, capacitor C1 is discharged, so current begins to flow through the +12 V circuit, the interior lamp EL1, C1, R1, the emitter junctions of transistors VT1, VT2 and the common wire. Transistors VT1, VT2 open. Due to the action of the feedback voltage generated by the circuit R1C1, a voltage of 1.4...1.5 V is established on the transistors, equal to the total at their emitter junctions (capacitor C1 is discharged, and the resistance of resistor R1 is low). The EL1 lamp maintains the on-board voltage (+12 V) minus the specified voltage drop across the transistors. The lamp shines brightly.
Capacitor C1 begins to charge, and the current through it decreases. This leads to a decrease in the base and collector currents of transistors VT1, VT2. The current through lamp EL1 and the voltage across it drop, and it goes out smoothly. The complete shutdown time depends on the power of the lamp EL1, the capacitance of the capacitor C1, the resistance of the resistors and the transmission coefficients of the current transistors VT1, VT2. In the author's version it is approximately equal to 5 s. To quickly discharge the capacitor when opening any door, a VD1 diode is installed.
The device can use medium (VT1) and high (VT2) power transistors of any type. In the case of using p-n-p structure transistors, it is necessary to change the polarity of connecting capacitor C1 and the polarity of connecting the device to the standard switch SF1 of the car. When assembling the structure, I used mounted mounting of the elements, placing the transistors on a small heat sink (Fig. 2). Since the transistors are in active mode for a short time (5s), installing them on a heat sink is not necessary.
A correctly assembled device does not require adjustment. If you need to change the time to turn off the lights in the cabin, you should select the capacitance of capacitor C1. The larger it is, the longer the delay in turning off the light, and vice versa. You can install the assembled device in any convenient place; I placed it in the center pillar of the car, next to the light switch. Due to the low current consumption when switched off, it does not affect the operation of the security alarm, also connected to the door switches.
Many people like smooth dimming of the interior lights, but not all cars have this function. In this article I will tell how to assemble a circuit for smoothly turning off the lights in the cabin with a delay of 3 seconds. The circuit was created for the Daewoo Lanos car, the colors of the terminal block are indicated specifically for this model.
In parallel with the addition of the soft shutdown function, it was decided to replace the standard interior light bulb with its LED Chinese counterpart, which generates much less heat, which, as can be seen in the photo, “crumbs” the plastic of the ceiling.
Scheme for smooth shutdown of Daewoo Lanos interior lighting with delay
The scheme is simple and does not require any special explanation. The first transistor has a shutdown delay. A capacitor and a parallel-connected resistor with a nominal value of 1M serve as a time-setting circuit; the higher the capacitance of the capacitor and the nominal value of the resistor, the longer the delay for turning off the light bulb. When connecting the “switch” pin to the ground wire using a “slider” switch, the capacitor’s capacitance is instantly charged through a 5 (kOhm) resistor. The diode after the resistor is not installed by chance. When the doors are opened, ground is supplied to the gray wire of the terminal block, and (as it turned out as a result of experiments) When the door is closed, the ground not only disappears, but is replaced by +12 volts. It was for the purpose of blocking the subsequent positive potential, which instantly discharges the capacitance of the capacitor, that a diode was added to the circuit. The second transistor (kt819) acts as an amplifier. The resistor in its base 1 (kOhm) determines the brightness of the glow; when using conventional incandescent lamps, it may be necessary to reduce its value to 300-500 Ohms and also increase the capacitance of the timing capacitor. Pay attention to the resistor connected in parallel with the load; in the case of using LED lamps, it is necessary to “extinguish” the lighting. This is due to the fact that when the voltage at the lamp terminals decreases to 7-8 Volts, the current consumption drops sharply and the lamp glows for a long time at 10% incandescence.
Implementing a smooth dimming scheme for light in the cabin is quite simple and does not require much effort. The circuit itself has small overall dimensions and can be easily placed in any convenient place in the car. In terms of the element base, everything is also simple, one capacitor, a pair of diodes and a pair of resistors, depending on the type of lighting.
The circuit is mounted on the terminals of the lighting lamp. Even a schoolboy can easily cope with the elementary scheme. The electrical circuit for cases where your lighting device is an incandescent lamp is shown in the figure below.
Let's take a closer look at the principle of operation. The first power supply diode. +12 V is used to protect against polarity reversal and reverse currents. Through the second diode (in parallel with the resistor), the capacitor is directly discharged to the incandescent lamp when the light is turned off. The capacitor ratings indicated in the diagram can be changed. In some car designs, the interior light is parallel to the lighting fixtures in the trunk, so a capacitor with a larger capacity may be needed.
In any case, after assembly, you need to check the work, and not immediately seal the circuit into the lampshade. A resistor with a resistance of 1 Ohm plays the role of a current-limiting resistor in case of transient processes when the lamp is turned on, the current can jump and burn all the diodes and the capacitor and blow out the fuse.
Now let's look at the diagram in the case of LED lighting fixtures in the cabin. The diagram changes a little, you can see it in the picture below. If you are at least a little familiar with electrical engineering, you should know that the charging and discharging time of a capacitor occurs in the so-called 3?, where? = RC, i.e. the product of the resistance in the circuit and the capacitance of the capacitor.
In the case of an incandescent lamp, when its temperature drops, it itself represents a resistor with a certain resistance; by adjusting the capacitor, you can easily select the required discharge time of the capacitor to the lamp. In the case of an LED, this does not happen, which is why it is necessary to add a discharge resistor to the circuit, which, together with the capacitance of the capacitor, will determine the discharge time of the capacitor.
In this circuit, the resistor value is 820 Ohms, but in each individual case it may differ. Therefore, before installation, it is imperative to check the extinction time of the lamp or LED; if the extinction values are set incorrectly, you can wait for minutes.
Device for smooth dimming of light in the car interior
I liked the circuit I saw on one of the amateur radio sites, made on the pic12f629 microcontroller. This device for smoothly extinguishing light in the car interior is more complex than versions of the device for smoothly extinguishing light that are found on many resources. But since the device contains a microcontroller, it naturally has many advantages over similar backlight circuits.
In this device there is no influence of external temperature on the decay rate, does not require any adjustments or adjustments, can be used both with LEDs,the same with incandescent lamps, and the proposed car lighting circuit has more useful functions.
So, the algorithm of the circuit is as follows:
- if you open and close the door, one warning signal will sound, the lighting will remain on for 20 seconds, and then gradually go out;
-if you turn the ignition key at this time, smooth extinguishing occurs immediately;
-if you turn off the ignition, the light will come on again and will remain on for 5 minutes unless you turn on the ignition again or open the door;
-if you open the door with the ignition on, three warning signals will sound;
The same will happen if you turn on the ignition with the door open.
-if you open the door (for example, in nature, listening to music), the light in the cabin is on for 5 minutes, and then goes out as unnecessary.
The lighting pattern is very easy to repeat.
