Friday, May 24, 2019

Single module for adjustable bench power supply 6Amp 1.2 to 25V

Single module for adjustable bench power supply 6Amp 1.2 to 25V

Portuguese Version: Click Aqui
Bench-top power supply for the Engineer, Technician, Designers, are of paramount importance, without a doubt, but, what draws the most attention, is that these power supply that are in the market, are low current, quite limited and are also very expensive, quality bench power supplies, are very expensive, and we can not afford any of us to buy so much.

Thinking about that, we have developed a module to use in our bench power supply, it is a fantastic project, because this module has voltage control adjustable from 1.2 to 35v, with a great power of 6 Amperes, with protection of short circuit, and temperature protection, a simple and low cost !!!

We will use materials that are easy to acquire and affordable to build a decent bench source.

The schematic is very simple, we use two LM350 ICs, each providing 3 Amps, together they will provide 6 Amps adjustable.

We will also use two 220 Ohms resistors for those who do not remember, the colors "Red, Red, Brown" and a potentiometer of 5K, if you want more precision, you can use a multi-turn potentiometer

And a universal printed circuit board, or, if you prefer, an insulated printed circuit board.

We will also use the SCHOTTKY S16C45C 16-Amp Barrier Rectifier from an old ATX power supply, if you don't have it, you can use two diodes with the anodes receiving the output of each LM, and the cathodes come together as one output, as suggested in schematic in the image

We will also use the heat-sink of the ATX power supply itself, with their respective insulators, don't forget that.

After the separate component list, let's mount.

Download the schematic so you can follow along with us, what I will do here on the universal board is to connect according to the schematic that I created, but I do not have it in printed circuit board layout, because the scheme is very simple, and you can do as you find the provisions of the components better.

After you have placed the two ICs and the Rectifier in the heatsink,
After docking, we'll place the two resistors.

The potentiometer, we'll not solder in the board, because usually we use the tension control potentiometer far from the plate, so I'll use a connector to make it easier to assemble or disassemble

Everything in place, now let's weld them ...

We will use this cable with the two-pin male connector and weld it to the Potentiometer ...

For you who think little 6 A, I have good news for you!

With this schematic that I created, we can double the current to 12 amps, which would be a powerful power supply of adjustable voltage with protection of short and temperature, what you have to do is only two modules of that and ready, you will have your output of 12 amperes.

It is very important before you turn it on, check that the Kis and Rectifier are really insulated from the heat-sink, and that there is no short circuit in the tracks.

After everything welded, we will connect a power supply, which in my case, is a 24V.
Remember, the output voltage will depend on the input voltage minus the supporting voltage of the ICs which is 1.25v, minus the diode loss which is 0.7v which results in input voltages less approximately 1.95v.
After being evaluated, everything OK.

Our load will be that halogen bulb used in 55w and 12v car mile headlamp.

As we already know the law of Ohms, Current is equal to Power over Voltage.

That means 55 watts over 12 volts, which is about 4.58A.

We set the voltage to 13.52v because this is the average voltage of a moving car receiving power from the alternator.

Let's put the load and see the voltage drop ....
Let's turn on the load.

It's there, with a load of 4.58 A, we get good stability in the module, having a voltage drop of only 0.4V.


Our design, working perfectly, for its simplicity, is a great simple and effective circuit.

For you that would like more details

Watch on our YouTube channel, this video with test details and everything. For English, active subtitle.

Thank you, good luck.

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God bless you.


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