DIY

Adjustable gimbal on TL431 with automatic cooling

Adjustable stabilizer on TL431 with automatic cooling Hello everyone! Today I will tell you how you can make your own regulated power supply on the TL431 chip, in which there is automatic cooling.
Before first I want to recommend you my video, here I showed the whole process of assembling this circuit.
Adjustable stabilizer for TL431 with automatic cooling The first thing we need to find is a step-down transformer, the maximum characteristics of the power supply will depend on it.
Adjustable stabilizer for TL431 with automatic cooling I took such a toroidal transformer (on one stream he was nicknamed the hedgehog  Regulated stabilizer on TL431 with automatic cooling ) with 19V output winding. The voltage on the transformer must not exceed 25V!
Adjustable stabilizer on TL431 with automatic cooling the diode bridge copes well with the task. I took the Chinese bridge KBU8K, it is 8A and you can easily remove 5A from it.
Adjustable stabilizer on TL431 with automatic cooling You can also make it yourself from four separate diodes.
Adjustable stabilizer for TL431 with automatic cooling I will solder everything on a homemade printed circuit board, which I made myself using the loot method. The board file can be downloaded from this link archive with board and diagrams .
By the way, you don't need to mirror it, I forgot and mirrored it, so the entrance will be on the right, and the exit on the left. Don't make my mistake!
Adjustable stabilizer on TL431 with automatic cooling The diode bridge will heat up during operation, so I will take it out on the wires, then we need to screw it to the radiator.
Adjustable stabilizer on TL431 with automatic cooling There will be 100- hertz ripples and to remove them we need to install a capacitor.
Adjustable stabilizer on TL431 with automatic cooling I took two electrolytes at 4700 μF everyone. Roughly speaking, we can say this: for 1A we need a 1000μF capacitor.
Adjustable stabilizer for TL431 with automatic cooling For better filtering, it would be nice to put another capacitor, but this time a film or ceramic. I took a 2.2μF film, this should be enough.
Adjustable stabilizer for TL431 with automatic cooling The voltage should increase 1.4 times, this is due to the fact that the capacitors are charged to the amplitude voltage, let's say we have a voltage of 19V on the transformer, and the voltage on the capacitors will already be 26.6V, with this voltage nothing will burn out and everything will be fine. And if we have 30V on the transformer, then the capacitors will have a voltage of 42V, at this voltage the TL431 microcircuit will fail, if someone did not know then this microcircuit can withstand a maximum voltage of 36V, and at 42V it will burn out.
Adjustable stabilizer for TL431 with automatic cooling We have finished with the first part of the BP, I present you with a schematic diagram of this node.
Adjustable stabilizer on TL431 with automatic cooling Next we need to make a voltage regulator. You can see the scheme in front of you, it is not complicated and should start the first time.
Adjustable stabilizer on TL431 with automatic cooling The first thing we need to solder to the board is three resistors: 2 resistors for 1K and one resistor for 100 Ohm.
Adjustable stabilizer for TL431 with automatic cooling The power of the resistors is not important. Resistors with a power of 0.125W are ideal.
Adjustable stabilizer for TL431 with automatic cooling To adjust the voltage, we need to find a 10K resistor, but you can take it and it will work at 20K at least 50K, just the voltage adjustment range will be different.
Adjustable stabilizer for TL431 with automatic cooling I recommend taking it out on the wires. I have such a connector lying around and I decided to put it here.
Adjustable stabilizer on TL431 with automatic cooling The main element of the circuit is the TL431 microcircuit, it is cheap and it will be easy to find it.
Adjustable stabilizer on TL431 with automatic cooling In simple words, we can say that the TL431 is a controlled zener diode and it does its job well.
Adjustable stabilizer on TL431 with automatic cooling Transistors went into action. One transistor is needed low-power, I took KT602 but any other transistors with similar characteristics will do. I recommend taking BD139.
Adjustable stabilizer on TL431 with automatic cooling Well, the main power transistor for me will be 2SC5200, which is powerful and, in principle, suitable for a power supply unit. The circuit is linear, that is, the transistor converts all excess voltage into heat! You should not take transistors in a TO-220 case, they can give 30-40W of heat no more, my transistor can dissipate about 70W, I recommend taking transistors in a TO-3 case, they can safely give off 100W of heat. It is best to take the KT827 transistor, it is composite and its collector current is good and the type of case is also good. We'll remember about it later.
Adjustable stabilizer for TL431 with automatic cooling
I will also bring 2SC5200 on wires. Also do not forget to heat shrink all contacts.
Adjustable stabilizer for TL431 with automatic cooling At this stage, the schema can already be tested. It worked for me, the minimum voltage is 2.5 volts and the maximum voltage is almost 25v. In fact, the maximum voltage is about 17 volts. We already know that the circuit works, so we can continue soldering.
Adjustable stabilizer for TL431 with automatic cooling It is advisable to solder a 100μF capacitor to the base of the transistor kt602 with it, the circuit will work better.
Adjustable stabilizer for TL431 with automatic cooling
Next, at the output of the circuit, we solder a 10K resistor, it will create a small load at the output.
Adjustable stabilizer for TL431 with automatic cooling Well, in parallel to the resistor, we solder the electrolyte at 100 uF. Well, don't forget about the non-polar capacitor, too, I took a 470 nF film. Without a 10k resistor, capacitors will discharge for a long time, the voltage will be displayed incorrectly.
Adjustable stabilizer for TL431 with automatic cooling The second part of the power supply is ready.
 Adjustable stabilizer on TL431 with automatic cooling We just have to solder the thermostat circuit for everything, it is not complicated, but it works well. I will say right away that I connected the LED incorrectly.
Adjustable stabilizer on TL431 with automatic cooling The circuit is powered by 12V, and on the diode bridge we have as much as 25V – that's a lot. Therefore, we will power the circuit through the voltage regulator KREN8B, but you can take any other modern analogue.
 Adjustable stabilizer on TL431 with automatic cooling I will also put the stabilizer on the wires, then we will screw it to the radiator, since it will be heated during operation. The microcircuit heats up due to the fact that it works in a linear mode.
On 1 and 3 legs of the stabilizer, it is advisable to solder ceramic capacitors 0.1 uf with them it will be better.
Adjustable stabilizer on TL431 with automatic cooling I solder an LED with a 22K current limiting resistor to the output of the stabilizer.
Adjustable stabilizer on TL431 with automatic cooling Now we have there is an indicator of the power supply.
Adjustable stabilizer on TL431 with automatic cooling As a temperature sensor with us a thermistor protrudes, when heated, its resistance will fall.
Adjustable stabilizer for TL431 with automatic cooling We use a 10K trimmer to adjust the sensitivity of the circuit. You can take an ordinary variable, but I advise you to take a trimmer resistor. With it, we will be able to more accurately set the desired operating temperature of the circuit.
Adjustable stabilizer on TL431 with automatic cooling there will be a field-effect transistor irfz44n, it is fake, but for this case it fits perfectly here, it should not heat up, therefore we will not screw it to the radiator.
Adjustable stabilizer on TL431 with automatic cooling We also need to find a fan I found it in a computer power supply. It is 12V and blows more or less normally.
Adjustable stabilizer on TL431 with automatic cooling We supply power and check the circuit and she works for me. I adjusted the circuit so that the fan starts spinning from the body temperature.
Adjustable stabilizer for TL431 with automatic cooling Behind the scenes I tested the circuit and unfortunately the Chinese transistor failed. It could not withstand a load of 4A at a voltage of 12V, the transistor was screwed to the radiator.
Adjustable stabilizer for TL431 with automatic cooling Therefore, I will take the previously mentioned kt827, it is definitely original and its characteristics are even better.
Adjustable stabilizer for TL431 with automatic cooling To cool the parts, we need a radiator, the bigger the better. Still, the scheme works in linear mode.
Adjustable stabilizer for TL431 with automatic cooling
First, I will screw on the transistor, I will not use thermal grease, since the body of the transistor is a collector.
Adjustable stabilizer on TL431 with automatic cooling We make a terminal from an ordinary wire, something like this should turn out.
Adjustable stabilizer on TL431 with automatic cooling This wire must be screwed to the radiator.
Adjustable stabilizer for TL431 with automatic cooling The voltage stabilizer must be screwed in through a special insulating gasket with a plastic washer.
Adjustable stabilizer for TL431 with automatic cooling Don't forget about the diode bridge, here I have already taken and smeared a little thermal paste.
Adjustable stabilizer for TL431 with automatic cooling I pressed the thermal sensor with such a thing, not very nice, but it holds tight. But beware, the sensor is fragile and may crack.
Adjustable stabilizer on TL431 with automatic cooling Well, we can say that everything is ready, it remains only to test the circuit.
A large multimeter measures the input voltage that is at the transformer, and a smaller multimeter measures the voltage at the output of the circuit. The circuit works great, the voltage is regulated. And this is very, very good.
Adjustable stabilizer for TL431 with automatic cooling Instead of a transformer, I will connect an adjustable power supply and at the input I will regulate the voltage and we will see how the circuit stabilizes the output voltage. On the diagram, I set the voltage to 12 V at the input, it was almost 24V, now I will change this voltage, the circuit stabilizes the voltage well.
At a voltage of 14V, there is already a drawdown at the output. Then I set the output to 5V and began to regulate the voltage at the input, and already at a voltage of 7V, there was a drawdown at the output. It turns out that the input voltage should be several volts higher than the output voltage.
Adjustable stabilizer on TL431 with automatic cooling Well, now we will conduct a test under load, as a load we will have such a traditional light bulb.
We expose 12V and connect the load.
Adjustable stabilizer on TL431 with automatic cooling At a current of 3 A, the voltage dropped but not very much, the stabilization is good.
Adjustable stabilizer on TL431 with automatic cooling Measure the temperature of the radiator we will be this kind of thing.
Adjustable stabilizer on TL431 with automatic cooling Now I want to run a 10 minute load test of the circuit. The voltage is the same 12V and the current is also 3A well, and the input voltage on the transformer will be approximately 19V. The temperature on the heatsink rises, the voltage on the transformer changes in one direction or another, but the output voltage is stable.
 Adjustable stabilizer on TL431 with automatic cooling At a temperature of 38 ° C, the fan started spinning, of course it is not working properly, but the temperature has stopped rising, after all, the fan is helping.
Adjustable stabilizer on TL431 with automatic cooling no problem
 Adjustable stabilizer on TL431 with automatic cooling Now there will be a very tough test of the circuit, instead of a light bulb, I connected a thick nichrome spiral. Under load, the voltage did not drop much and the current was already 15A. Well, I will not torment the circuit with this current, since it is not designed for it.
And that's all, I hope you enjoyed my article, bye everyone!

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