Converter for computer subwoofer to car

Computer subwoofer-to-car converter Hello everyone, I want to tell and show one of the converter options for connecting a small computer subwoofer to the car.
The circuit, the board and my thoughts will be on the link in the description under the video.
converter !!! and not about the budget subic, which is shown as an example in my video. I have enough of this too.
As it turned out later, this subic is rather weak for a car, but I'm talking about a converter for a subic, nothing prevents me from putting a more powerful subic and making this converter under its operating voltage!
Many people just buy a 12V – 220V inverter and already feed the subic from 220V. Yes, it's simple, but this option has drawbacks, for example, this inverter is constantly connected to the battery and at idle (when the radio is turned off) it always has its own consumption. This means that if you put the car in the garage for a couple of weeks in winter due to frost or a business trip, then the battery will be discharged and you will definitely not be able to start the car without recharging in winter. This problem can be solved by taking the signal to turn on the radio and, through a regular relay with 30 A contacts, supply power to the inverter when the radio is turned on … But the inverter costs money, and a radio chiller like me always has almost all the details, plus Aliexpress and free winter evenings for making another homemade product ….
I decided to assemble a converter from a unipolar voltage of + 12V to a bipolar pole – minus 20V.
This makes it possible to hide the converter in the case of the subic.
When opening the subic, it turned out that the subic still did not die as a result of the autopsy 馃檪
and it is powered by a two-pole voltage plus or minus 20V.
Converter for a computer subwoofer into a car Then, a little bit of pogo-u-gliv, I found a simple circuit of the converter I needed on the TL494, especially since I am well acquainted with the operation of this PWM by converting a computer power supply into a charger for a battery with protections.
 Converter for computer subwoofer to car After some magic over the circuit, I made the output 18V with an input of 11.5. When the engine is running, the voltage rises to 22V.
I want to say right away that to calculate the transformer of the converter, it is imperative to know the EXACT brand and dimensions of the ferrite core! Otherwise, it will either not hold the load, or it will get very hot! I fully felt it all! FIVE times rewound the trance and selected the PWM frequency to achieve a normal result! Do not get fooled by the assurances of youtubers that they say they took the first core they came across and wound the average values 鈥嬧媜f turns on it and voila … Everything works …. Although maybe someone was lucky …
Corrected the author's PCB for the details I have.
 A converter for a computer subwoofer into a car And collected up to a heap …
Converter for computer subwoofer to car Converter for computer subwoofer to car This is how it looks in the subik case with the back cover removed.
Converter for computer subwoofer to car As it turned out in the process operation, this particular subic is rather weak, but we are talking about a converter and by changing the output voltage and power you can easily attach a subic much more powerful !!!
The converter works like this:
The main one (power supply, specifically in my case, is connected with a wire of at least 1 mm. Sq.) Is fed to the circuit through the fuse FU1. The VD1 diode is connected in the opposite direction to protect against reverse polarity. If a reverse voltage is applied, the diode will refuse to open and all current will flow through its junction. This current will be large enough to cause the fuse FU1 to blow. The circuit will break, the converter will de-energize and will not burn out.
Then the voltage is filtered by the C1, L1, C2-C5 filter. Then it enters the midpoint of the transformer T1, also through the resistor R2 on the 12th leg of DA1. In this case, a reference voltage of + 5V will appear on the 13th output of DA1, which is fed through the resistors R4 and R3 to the 4th leg of DA1 and blocks the operation of the PWM. There is no PWM signal on 9 and 10 legs and the converter does not work.
To turn on the operation of the converter, you need to apply a voltage of + 12V to the resistor R14. This is necessary so that when the radio is turned off, the converter does not discharge the battery at idle … In a couple of weeks, while the frosts are big or you are on a business trip, the battery can lose so much weight. Youtubers are usually silent about this, I praise my homemade product …
The turn-on signal is taken from the radio itself (now all radio receivers have a +12 V output when the radio itself is turned on to control the amplifier). So this signal +12 is fed to control the switching on of the converter to the resistor R14, then to the base VT7, it opens and we feed a minus through the resistor R3 by 4 legs. At the same time, the capacitor smoothly discharges and a soft start of the converter occurs, excluding shock loads on the power elements. This moment is also considered by many homemade products to be superfluous, but in vain.
On the 4th leg, the power supply minutes (logical 0) appeared and the microcircuit started. The PWM frequency is set by the resistor R1 and the capacitor C8. The higher their ratings, the lower the PWM frequency. This is calculated in the OLD MAN 51 program. I personally preferred a frequency of no more than 36 kHz. and this is my personal opinion and I do not impose it on anyone!
The PWM started working and PWM signals with maximum filling appeared on its 9 and 10 legs, in this circuit there is no stabilization of the output voltage. Then the PWM signal is fed through resistors R5, R6 to simple drivers assembled on R7, R8. VD1, VD2. VT1, VT2, which quickly discharge the gates of the transistors VT3, VT5 (in my case) when the transistors are closed. These transistors open and switch the alternating high-frequency current in the primary winding of T1.
Then, from the secondary winding, the alternating voltage is rectified by fast diodes VD4-VD7 and filtered by the filter C12, C13. L1, L2. C14-C23.
At the output, we get a constant bipolar voltage plus or minus 20 V with an average input of 13.5 V. It depends on the winding trance data and the PWM frequency.
Connect to subik and listen to music …
Tuning: This process for beginners can be a little complicated, I also ran into certain difficulties for the first time …. < br>The main criterion is the choice of frequency and winding data of the transformer. In such simple circuits, I prefer a low conversion frequency, no more than 36 kHz. In this case, it is much easier for output field workers with a budget driver to open and close with minimally gentle fronts. The higher the frequency, the more shallow the PWM fronts will be on the gates and the more the transyukas will start to warm up. This is when using a budget driver on one transyuk, from personal experience!
Determine the frequency, then you need to know the real brand and permeability of the core used!
The following images are given as an example of calculation and cannot be taken as a basis in your case !!! I got completely different values 鈥嬧媌y choosing …
Open the browser and online calculate the PWM frequency
 Converter for computer subwoofer in the car Next, open the OLD MAN program and calculate the trance based on the frequency (in this example, 36 kHz) and the available core (in this case, the ring 200NM 40x25x11)
Converter for a computer subwoofer in a car This is all shown only as an example !!!
In my case, the seller did not know the permeability of the core and there was no marking on the ring itself! And I had to pick up the winding data!
If everything is correct, then nothing heats up at idle (no load), and under maximum load the radiators heat up no more than 70 degrees.
If not, then you need to adjust the calculations …
For example, if it heats up even at idle running, then the core obviously goes into saturation and you need to add the number of turns to the primary winding and it is possible to change the number of turns in the secondary.
And if it does not hold the load and the output voltage drops heavily, then most likely it will be necessary to reduce the number of turns of the primary winding. This is from personal experience and I do not impose it on anyone!
R2 15-25 Ohm with a power of 0.25 – 0.5 W.
R1, R3-R12, R14 Ratings according to the diagram with a power of 0.125 -0.25 W, for example MLT 0.125.
R13 The snubber resistance is calculated in the program, for example, an old man51, with a power of at least 2 W. For example MLT 2.
VD1 Any powerful one with a current from 10 (preferably from 15 Amperes) and a reverse voltage of 40 V. For example, you can put a double diode from a computer 16C40, 20C40, in a TO-220 or 30C40 case in a TO-247 case ….
VD2-VD3 IN4148 or its analogs
VD4-VD7 Fast diodes KD213A-B, you can also KD2999A. You can also use any fast diodes with a current of 10 Amperes (with a margin) and a reverse voltage of at least 200 V.
VT1-VT2 BC556 or its analogues.
VT3-VT6 IRFZ44 or yoke analogs with a maximum Stoke-Source voltage of at least 50 V and a current of 25 A and a gate capacity 1 -1.5 pF.
C1 Film with a capacity of 1 渭F with a voltage of 50 V, for example K73-17.
C2-C5 1000-2200 渭F electrolytic with a voltage of at least 25 V, for example K50-35.
C 6 Ceramic 100 nF with voltage from 25 V.
小7, 小9 Electrolyte 22渭F with voltage not lower than 25 V. For example 袣50-35.
小10 The capacitance of the snubber capacitor is calculated in the program, for example, an old man51 based on the specified parameters.
小12 , 小15 100 nF ceramics with voltage from 50 V.
小16-小23 Electrolytes 1000 渭F with voltage not lower than 35 V. For example K50-35.
DA1 TL494 or its full analogue, for example 袣袗7500. < br> Chokes:
L1-L3 I didn't bother with the calculations, I took the ready-made ones from the computer power supply. In my case, they came, but this does not mean that in your case I will come too. My frequency of my converter was close to the frequency of the power supply unit from which I took the choke ….
T1 In my case, I wound it on an unknown ring 40x25x11 in size and grabbed a lot of sex with the selection of winding data.
In your case, you need to know the permeability and brand of the core, as well as the frequency of the PWM and the rated load current. Open the old man's program51, enter all the data and get the calculation of the trance windings.
FU1 for a current of 10-15 Amperes. I bought a portable car with a case. You can buy at a car market or a car shop.
Converter for computer subwoofer to car In general, it somehow happened … This converter has been pulling my budget subic in the car since the summer of 2018 ….


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