I rarely use my car. In fact, it is not clear why he me. Well, as a result, the battery always “sits down”. And every time I have to attach a spare battery, and put the dead one on charge. This is an eternally painful problem - to prevent the battery in the car from being discharged below normal.
Therefore, I put together this “Car battery voltage indicator” circuit, which I found on the Internet a long time ago and kept with me.
But I changed it a little, and instead of the 10 individual LEDs that were in the original circuit, I used a 10-segment LED indicator, because. it takes up less space.
Required radio parts:
1. tuning resistor 5k - 2 pcs.
2.LM3914 chip
3.10 segment LED bar (I used Kingbight DC-763HWA)
4.resistor R1 4.7k
5.resistor R2 1.2K
6. For adjustment, you will need a voltmeter and an adjustable power supply from 10 to 15 volts.
Here is the PCB of the device.
As you can see in the photo, I cut off one lead from the right trimmer.
After mounting the parts on the board, the device must be configured. Apply 10.5 volts and adjust the right trimmer until the first bar on the 10-segment display lights up.
Apply 15 volts and adjust until the last bar on the 10-segment display lights up. And remember, only one strip should always glow. Mount the device in a convenient location.
You now have a 10-segment display showing battery voltage in 0.5 volt increments.
For the first time, I was offered to write a review on the product by representatives of the store, my choice fell on a car USB charger under the iMars brand with two ports and a voltage and current indicator. The ultimate goal was to replace two devices in my father's car - a voltmeter in the cigarette lighter, with which my father controls the battery voltage and the need to charge it in winter, as well as a simple noname phone charger with a maximum current of 500mA.
The manufacturer promises maximum charging current 4.8A (2.4A+2.4A), measuring the voltage of the car's on-board network and the charging current of connected devices. Let's see if it will be possible to replace two devices with one and whether the manufacturer's promises will be confirmed further ...
The charger was packed in a cardboard box, inside of which was the charge itself. No instructions or anything like that. Everything on the box is in English.
Unboxing
Immediately after receiving the package, I decided to test the charger in my father's car (VAZ 2111) to see if it works. And then the first problem awaited me - the charger did not reach the central contact of the cigarette lighter in this car in length ... I tested it in my Skoda Fabia - the charging worked, but it was somehow not very convenient to carry out tests in the car, so I decided to power the charging at home from the power supply on 12V through the cigarette lighter connector to a cable bought once on aliexpress. And then the second problem awaited me - in this connector, the charger also did not reach the central contact. The depth of the charger at 39 mm turned out to be too large ... So even without starting testing, we can say that the charger is not suitable for all cars and connectors, the maximum depth at which it will work is about 37 mm.
Somehow, with the help of wires and blue electrical tape, I connected the charger to the power supply from the laptop, the charger displayed a value of 16.8U. 
Well, the first simple test - I connected the iPad mini to the charger, it's charging. Approximately every 2 seconds, the indication, voltage and charging current change. Shows current 2.15A.
Next, you need to check the manufacturer’s statement about the maximum current of 4.8A, but unfortunately I don’t have a USB load, which many people here use to test chargers, so I came up with using car incandescent lamps as a load (warm lamp load, in the literal sense of the word ).
I connected a 12V H4 autolamp to the charger via a USB tester - the charger displays a current of 2.32A, the tester shows a little less, 2.14A
Let's continue testing, I'll try to connect the phone to another port together with the lamp. Since I don’t have a second USB tester, I use a multimeter to measure the lamp current, and a tester for the phone. And then a surprise, the phone shows that it is charging, but the tester displays a very small current, only 0.09A.
Let's try to load the charger more. I connect the H4 bulb to one port, the same as in the first experiment, and to the second - a 24V autolamp - it has more resistance, the current will be less.
Result - 3.03A is displayed on the charger, on the first lamp the current is 2.1A (the limit of 5A is selected on the multimeter, look at the lower black scale), on the second lamp the current is 0.66A. In total, 2.76A comes out, the difference with the charging readings is 0.27A. The voltage at this sank to unacceptable 4.42V.
Well, let's try to get the most out of this charge - I connect the same 12V H4 lamp as in the first experiment, only using a much shorter USB cable. If you connect it to a working charger, then the protection is activated and the charging is turned off, but if you first connect the load, and then apply power to the charger, the lamp lights up:
The charger shows us a current of 3.28A, while the screen flickers noticeably more. The multimeter shows the current through the lamp 2.9A. At the same time, unfortunately, it was not possible to measure the voltage, since the USB tester was wildly sausage, all segments were lit on the screen, the lamp connected through it was not lit. It can be concluded that the maximum current that these chargers can produce is about 3A, but due to voltage drops and ripples, no phone will charge.
You can disassemble the charger quite easily by picking up the silver display frame with something sharp. The part covering the display is held on by latches on the sides. Having removed it, the inner world of the charger opens up to us:
The protective film has not been removed on the screen, if it is removed, the numbers on the indicator will be clearer.
If you pull the USB connectors, you can get the charger boards. It consists of two parts connected at right angles - on the larger board there is a switching voltage regulator, on the smaller board there are USB ports, a display and a circuit for measuring and displaying voltage and current.
Summing up, I want to note that the manufacturer, as always, indicated overestimated current characteristics, the charger will not be able to give out 4.8A, the maximum that you can count on is about 2.4A for both ports. Also, the shape of the charger will not allow it to be used in some cars with a deep cigarette lighter socket. In general, I liked the device, it is convenient that it combines the function of a charger and a voltmeter, the current measurement function seems to me not so useful. After the review, I still plan to give the charger to my father, but for this I will replace the cigarette lighter socket with another, more standard one (since there are problems with many chargers in the cigarette lighter on the VAZ 211x).
Finally, I want to note that banggood has sales, most recently there was a discount on this charger and it cost $3.69
The product was provided for writing a review by the store. The review is published in accordance with clause 18 of the Site Rules.
I plan to buy +10 Add to favorites Liked the review +10 +19The device is connected to the car's on-board network and is designed to quickly determine its status by four LEDs. Which indicate the following voltages:
If two adjacent LEDs blink, then the voltage is at the boundaries of the specified intervals. Let's take a look at the diagram of the device, which is assembled on just one chip:
Before us are four operational amplifiers D1.1 - D1.4, connected according to the comparator circuit. Each of them, with the help of resistive dividers, is tuned to its own range and controls its own LED. The controlled voltage is supplied to the inverse inputs of the amplifiers, on the direct ones - the exemplary voltage obtained using the simplest stabilizer (VD1, R7, C1) and resistive dividers R1 - R6. Thanks to the diodes VD2 - VD4, the ignition of each next LED (from bottom to top) turns off the previous one. Thus, at any given time, only one LED is lit or none is lit (voltage is below 11.7 V). Inductor T1 and capacitors C2, C3 form a filter that eliminates impulse noise in the power supply circuits of the device.
In the device, you can use any fixed resistors that you want to choose as accurately as possible. Since there is no 500 Ohm value in the standard series, the R4 resistor is assembled from two 1 kOhm resistors connected in parallel. Trimmer resistor R5 - multi-turn, for example SP3-19a. Capacitors C2, C3 - K73-9 for an operating voltage of 250 V, C1 - type K10-17. In place of VD1, any zener diode of the D818 type can work, but the most thermally stable with the letters E, D and G. As LEDs, you can use any indicator with the lowest possible glow current (ideally - a series of instrumentation). Diodes VD2 - VD4 - any pulse.
The inductor is made on a K10x6x3 ferrite ring made of 2000NM1 ferrite and contains two windings of 30 turns each, made with PELSHO-0.12 wire. When turning on the throttle, it is very important to turn on the windings in a coordinated manner (the beginning of the windings is indicated by dots), otherwise there will be no sense from it as a filter. Setting up the device comes down to adjusting the resistor R5, which sets the lower indication threshold (below 11.7 V, HL4 has just gone out) and, if necessary, selecting R1 according to the upper threshold (above 14.8 V, HL1 has just turned on). All intermediate ranges will be set automatically. The current consumption of the device should be within 20 - 25 mA.
Not all cars have control over the voltage of the on-board network. Previously, in domestic cars there was an ordinary light bulb in the shield, which signaled that the battery was charging. This, of course, is not enough information. It would not be superfluous to install an additional digital voltmeter or at least an indicator of several multi-colored LEDs showing the main thresholds for permissible voltages. Below are three simple circuits for auto voltage LED indicators.
Voltage indicator on LM393
The operating voltage of the on-board network of a car with a 12-volt battery is considered to be a range of values from 11.7V to 14V.
If this range is exceeded, there may be bad consequences, since if the voltage drops below 11.7 V, the battery will be sharply discharged, and if it exceeds 14 V, it will be recharged.
To control the vehicle's on-board network, I propose to assemble a simple indicator consisting of two comparators made on the same LM393 chip and three LEDs.
The current voltage is taken from the voltage divider, built on the resistances R2, R3, R4 and compared with the reference, on the zener diode VD1). Normal voltage - green LED is on, more than 14V - red and yellow LED lights up if the voltage drops below 11.7V
Voltage indicator on K1003PP1
The device allows you to control the voltage of the on-board network in four intervals.
- When the battery voltage is below 11 volts, the red LED-VD1 is lit,
- with a normally charged battery from 11.1 to 13.2 volts, the green LED VD2 lights up,
- in the range from 13.4 to 14.4 volts, the yellow LED is lit - VD3,
- at an overvoltage of more than 14.6 volts, the red LED VD4 will light up.
The adjustment of the circuit consists in adjusting the range of a normally charged battery (12-13.8 V) with a 10K variable resistor. The phototransistor controls the brightness of the LEDs depending on the level of ambient light. You can completely exclude it, then the brightness will be maximum.
Multilevel voltage indicator on K1401UD2A
This circuit is also used to monitor the state of the on-board network and allows you to extend the life of the battery, preventing it from being discharged by more than half. This indicator monitors the battery voltage level with very high accuracy and informs the driver about its condition.
The device circuit is made on only one domestic microassembly K1401UD2A and consists of four comparators on operational amplifiers, which, using HL1 ... HL4 LEDs, inform the driver about the current voltage level in one of the intervals. According to the simultaneous burning of two indicators at once (or their “blinking”), you can accurately calculate the moment the battery voltage is at the border between the intervals.
If none of the LEDs is on, then this only indicates that the battery voltage is below 11.7V. The glow of HL1 tells the driver about problems in the operation of the voltage regulator - generator - so with the engine running, the generator must constantly charge the battery, but the voltage from the stabilizer should not be higher than 14.8 V. If the HL4 LED is on, this indicates that the battery is low more than 50% and needs to be recharged.
The design uses capacitances C1 of type K10-17, C2, C3 of type K73-9 for 250 V, a trimming small-sized resistance R5 of type SP3-19a, and other resistances of C2-23 (or similar small-sized ones).
The T1 inductor is built on a ring core with a size of K 10 x 6 x 3 made of ferrite grade 2000 NM 1. The windings have 30 turns of wire of the PELSHO-0.12 type. The throttle, when the phases of the windings are turned on correctly, protects the device from pulsation and interference in the vehicle's on-board network when the engine is running.
When installing the proposed indicators in a car, it is necessary to pay attention to the fact that its corresponding elements are carefully isolated from the car body. The negative terminal must be isolated from the body, and the positive terminal from the ignition switch. In this case, the voltage indicator will register the battery voltage only while the car is moving.
Keep the voltage of the on-board network of your car always under control!
P O P U L I R N O E:
In wired microphones, sooner or later, in places of bending at the microphone or connector, the wire breaks, twists along its entire length and interferes. Rattling, distortion, hum and loss of sound begin. In the radio microphone, this drawback is absent.
You can buy a radio microphone, but it costs several times more than a regular one.
The simple radio microphone proposed in the article below can be made with your own hands from the available elements. You can receive a signal from a microphone on a regular FM receiver.
Point-to-point for beginners. Plate painting.
dot painting (point to point) is a kind of arts and crafts, long known in the tribes of Indian and Australian aborigines. Today, dot painting is becoming increasingly popular. In this technique, it turns out to create very beautiful works, you may not even have drawing skills.
Vehicle voltage indicator, given in this article, is intended for visual control of the voltage of the on-board network of a car. Everyone knows that the normal voltage value available in the vehicle's on-board network has a positive effect on the battery life (battery), especially in winter. Therefore, in severe frosts, it is advisable to use to start the car engine.
It should be such that with a good and running engine, the generator would be enough for all energy consumers. And at the same time, it should not be too much, as this can lead to overcharging the battery.
Description of the voltage indicator of the vehicle's on-board network
Optimal voltage of the car's on-board network with a 12V battery, it is customary to consider the range from 11.7V to 14V. Going beyond these limits is highly undesirable, since when it drops below 11.7V, a sharp discharge of the battery occurs, and when it exceeds 14V, it starts recharging. You can control the vehicle's on-board network using a simple indicator consisting of two comparators and three LEDs, the diagram of which is shown below.
Indicator scheme very simple, the essence of its work is that the current voltage taken from the divider built on resistors R2, R3, R4 is compared with the reference voltage built on the zener diode VD1 (5.6V). The optimal voltage is indicated by a green LED, a state of over 14V is indicated by red, and accordingly yellow indicates below 11.7V. The OS used in this circuit
