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Taller de Electrotecnia


Someone want to make simple but practical DC power supply?

For almost all electronic projects, we need a good reliable source of power supply.

This is how we can make relatively simple and small, yet reliable DC power supply 1.25- 20V  2.5 Amp


The first step is transforming 220V to 18V. For this purpose, we have a transformer of 220/18V

After this, we still have an alternating current. In the most simple explanation, this is fast polarity changing current , plus and minus change positions. In our case, 55 times in one second or 55Hz.

This from of eletricity is not suitable for most electronic equipments.

So, we need to create a direct current or non polarity changing current from AC.

We can accomplish this with diodes. The most simple explanation for diode is that it is one way valve for eletricity.

So, after this, the next step in our power suply is the diode bridge. The function of the diode bridge is the prevention of polarity changing and making a pulsating current. While this is better than AC, it is still not suitable for our purposes.

For this purpose, we need a steady DC. To get a steady DC, the perfect solution is the usage of capacitors, which, in this case, are just big storage tanks of eletricity.

After this step, the voltage is finaly almost pure DC. Or to be more precise, 18V AC after diode bridge and capacitors become 25.38V DC

This looks good, but for most little projects, it is still a little too high.

The final step is to use a classic linear regulator LM350. So, we can enter with 25V and get 12V, 6V, 3V, etc  at exit.

Use of regulators is very simple and exit voltage is regulated by resistors between the “adjustment“ pin and the ground.

Finally, after 5-6 hours of drlling, cutting, soldering, making white smoke… we have our  regulated power supply for lights, motors, battery charging, or almost any kind of small projects.

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