Power supply interference is a problem for many motorists who want to use communication equipment in their cars. They fight with them in different ways and by installing ferrite rings on the power wire. Or you can install a factory product called a serial power filter.
I was interested in this little box that promises to remove all interference on reception. She looks completely inconspicuous. Just a box and 3 wires. As it is written on the package, we connect the red wire to the power source, connect the black wire to ground, and connect the radio station or radio tape recorder to the white one.
This miracle costs 250 rubles and inside she has this.
To be honest, I did not imagine that there could be something else inside, but I was more surprised by the quality of execution.
In fact, it is a single-link H-filter consisting of inductance and capacitance. Classic.
The inductance of the choke, measured with an LC meter, turned out to be about 0.290 mH. The capacity of the capacitor is 33μF.
Without going into technical details, such a filter is able to effectively deal with interference that creeps through the power supply to a radio station operating in reception or to a car radio. For transmitting equipment, you will have to come up with something more efficient.
However, the efficiency of the filter can be increased by adding electrolyte to the filter inlet and parallel to it a small film capacitor. For example, 100μF (or more) + 10nF.
Due to the fact that many cars do not provide a standard place for a whip antenna or standard car antennas are not installed, active car antennas, which have small overall dimensions and are installed inside the cabin on the windshield, are gaining more and more popularity.
Active car antennas LLC "NPP" ORION SPB " and SUPER allow you to receive radio broadcasts in all frequency bands at any distance. Easy to install and connect in the car.
Antenna mustache
Your car has a good active antenna, the receiving webs (whiskers) of which are damaged. This can happen for various reasons: the windshield is broken, or caught and torn when cleaning the windshield, or for other reasons. Previously, you had to throw away an expensive antenna and spend money on buying a new antenna. It's much easier now. There is a set of spare whiskers for car antennas.
The whiskers are universal, they are suitable for antennas of different manufacturers. Installation does not require special qualifications and is described in detail in the instructions.
Antenna amplifiers
The use of these amplifiers makes it possible to increase the reception range of radio stations by 2-3 times. The amplifiers are compatible with any type of whip antenna.
Passive power filter for installation in cars with an on-board voltage of 12 V. The filter is designed to eliminate high- and low-frequency interference generated by surrounding power devices that can affect the operation of connected video devices (image distortion) or the audio path of connected devices (create additional sound interference ). Maximum load 2 A.
Power filter
Connection example
Attention! The filter is sold wirelessly!
Power filter
Notes
Please pay special attention to the most common mistake. In no case should you take the negative pole of the power supply (ground -12V) from the case of devices connected nearby!
As a result of such a connection, the effect of potential difference appears, which causes errors and interferences in the operation of the connected devices. In this case, the filter will not help.
Plus and minus must always be taken from one place, for example, from a standard radio, taking into account that the circuit to which you are connected must have a power reserve and withstand additional devices.
The complete set, appearance and characteristics of the product may differ from those presented on the website and be changed by the manufacturer without notice. Check with the manager before buying.
Copying materials from the site is allowed only on condition that the authorship is indicated and a reverse text link is placed on each copied content.
Although we already live in the 21st century, at a time when our spaceships ply the vastness of the universe, in our native society there still exists a certain caste of car owners, in whose cars there is no filter to power the car radio. They are not confused by the low quality of the sound emitted from the speakers of their speaker system, or wheezing, or the hum or the hum of the engine.
Of course, all these problems can be easily solved by replacing the old car radio with a more modern digital and multifunctional one with processor control, but, unfortunately, sometimes this proven method does not help either. Therefore, in this article, you will find instructions on how to identify and eliminate unnecessary noise from car acoustics with your own hands.
Causes of noise and how to eliminate them
Since the price of the issue of replacing the car radio with a new one does not suit us, I propose to find the cause of the extraneous noise with our own hands, in the old proven way - by the method of elimination. And in order to increase the chances of early identification and elimination of the culprit of interference, I advise you to start from larger to smaller, namely from the head unit to the periphery.
Radio cassette
We take out the car radio from the seat (by the way, the background may disappear already when the head unit is dismantled) and then:
- Let's try to disconnect the antenna plug. Phonitis? Move on…;
- Using any suitable wire (see), bypassing all connections and connectors, we lay plus and minus to the head unit directly from the battery;
If the noises have disappeared, then this means that the main character of this performance is poor power contact (by the way, one of the symptoms of poor contact is also noises arising when the volume is increased / decreased).
Both supply wires of the device must be equipped with fuse-links in order to protect the acoustic circuit of the car. In case of periodic extraneous noises, it is recommended to add a capacitor to the power supply circuit of the car radio between the positive and negative terminals, which will essentially work as a power filter for the car radio, that is, to smooth out current fluctuations in the power supply circuit of the radio, stabilize its operation and eliminate possible sound interference.
Advice! Typically, the positive terminal is designated "A7" (yellow / red wire) and the negative terminal is designated "A8" (black wire).
By the way, with this refinement, we kill two birds with one stone - we eliminate the interference and get rid of one more problem, namely the pause that occurs during the operation of the car's starter, when all current consumers are turned off, including the radio tape recorder.
So, we put a more capacitive capacitor in the "head" power circuit, for example, 2200mkf - 16 volts, paired with a diode designed for the same current as the car radio fuse (for example, five-ampere diodes KD 210 and KD 206 are suitable for a five-ampere fuse, so and ten-ampere D 214 and D 215).
Attention! The diode must be soldered onto the positive wire, otherwise, when setting the car to the alarm, it will be necessary to wait a while until the capacitor is discharged.
We dump all this "business" on the table and solder it, as shown in the diagram in the photo:
Advice! Each car radio has its own time delay for loading the information carrier, as well as its own individual characteristics of current consumption. Therefore, you may have to independently select the capacitance of the capacitor for your car radio (the larger the capacity, the longer the autonomous mode of the car radio).
- If the name of the manufacturer of your car radio is even slightly similar to the Pioneer brand, then you can try the following trick:
Try to forward the "mass" to the line outputs of the device, that is, to the external "skirt" of the RCA connector.
The fact is that when the fuse of the line outputs fails, it is on the radio tape recorders of this brand that the device starts to "faint" terribly both on a stationary car and with the engine running.
Attention! The appearance of this malfunction is possible with connections between the blocks during the operation of the amplifier or the head unit, as well as with a short-term short circuit of the amplifier outputs.
Sound amplifiers
So:
- We check for a good RCA contact - the amplifier connector, if necessary, we solder them;
- We lay, instead of the disconnected "REMOTE" wire, in addition to all connectors, a positive wire to the device from the battery (12 Volts);
- Let's try to change the location of the "amp", it is best to take it out of the car (it happens that the fuel pump itself creates a tangible background during its operation);
- The amplifier housing must not come into contact with the vehicle ground;
Interconnect cables
- The "tails" of the screens (not the ground!) Must be securely fixed to the amplifier body, and the tail of the interblock to the head unit;
- Disconnect the interblocks from the car radio and the sound amplifier (see) and "ring" them for poor contact, its breakage, as well as for a short circuit with the car body;
- We try to change their location, listen to the background and shift them through the air, preferably outside the car.
Crossovers
We check the crossovers in the same way by moving to another place while listening to the background.
Speaker system with wires
We call each wire for a short circuit with the car interior.
Other possible causes
So:
- All grounding points, in order to avoid the "ground loop" effect, should be brought together at one point (combine the mass of the head unit with the mass of the amplifiers);
- Eliminate contact of absolutely all system components with the car body / ground;
- Clean and tighten the battery terminals (with contact ignition, check and clean the distributor contacts);
- Try to temporarily change the battery and ignition system elements (spark plugs, high-voltage wires, distributor).
As you already understood, interference can be "caught" from any other vehicle equipment, be it xenon, parking sensors, spark plugs and high-voltage wires of the ignition system. That is, all systems powered by the vehicle's on-board system, one way or another, "faint".
And in order to exclude their influence on the quality of the reproduced sound, you just need to install a filter in the electrical circuit of the connection (see) to power the car radio. Well, since we are not a bastard, then this instruction ends with simple recommendations, as you cannot understand, so I suggest you make a power filter for the car radio with your own hands.
Homemade power filter
I bring to your attention two very simple but reliable ways on how to make your own power filter for a car radio. The main advantage of the presented self-made devices is their price and ease of manufacture, which in no way relieves you of personal responsibility for the possible consequences of connecting homemade power filters.
Method one
This circuit represents four capacitors and a coil:
- The capacitances of the capacitors are taken at 4700 and 1000 microfarads (be sure to shunt them by 0.1 microfarads);
- A coil with an inductance of 100 microhenry has a winding on a ferrite ring made of enamel wire with a cross section of 0.9.
The advantage of this circuit is that in it each element plays the role of a kind of filter: electrolytic capacities smooth out various noises and pulsations, and shunt "conductors" eliminate high-frequency interference.
Advice! It is advisable to tin the conductive tracks on the "signet" with a thick layer.
Second way
The circuit of this simple LC filter also consists of a coil with capacitors, albeit with the addition of reverse polarity protection (diode) and a fuse.
Before assembling the circuit, we need to make a choke, which will also consist of a ferrite ring and a winding wound on it in the form of 10 ... 15 turns of wire with a cross section of 1 ... 1.5 millimeters (for convenience, you can use three wire cores with a cross section of 0 , 5 millimeters each).
Advice! Instead of a ferrite ring, you can use the iron powder ring that is used in computer power supplies (white or yellow ring).
The advantage of this particular circuit is that it works with a very wide range of nominal values \u200b\u200bof the components included in it. The capacitance of the capacitors is not critical and varies from 1000 to 4700 uF (the more, the better), and it is also possible to use electrolytes with voltages from 16 to 100 Volts (more voltage does not make sense).
On this, the instruction on how to make a filter for a car radio yourself has come to an end, I hope it will come in handy for you and rightfully occupy its niche in your personal piggy bank of useful tips.
Passive power filter for installation in cars with an on-board voltage of 12 V. The filter is designed to eliminate high- and low-frequency interference generated by surrounding power devices that can affect the operation of connected video devices (image distortion) or the audio path of connected devices (create additional sound interference ). Maximum load 2 A.
Power filter
Connection example
Attention! The filter is sold wirelessly!
Power filter
Notes
Please pay special attention to the most common mistake. In no case should you take the negative pole of the power supply (ground -12V) from the case of devices connected nearby!
As a result of such a connection, the effect of potential difference appears, which causes errors and interferences in the operation of the connected devices. In this case, the filter will not help.
Plus and minus must always be taken from one place, for example, from a standard radio, taking into account that the circuit to which you are connected must have a power reserve and withstand additional devices.
The complete set, appearance and characteristics of the product may differ from those presented on the website and be changed by the manufacturer without notice. Check with the manager before buying.
Copying materials from the site car-solutions.com is permitted only on condition of attribution and posting a reverse text link to each copied content.
