Continuing with a series of electronic tutorials today, I bring you a relatively simple circuit to regulate the voltage. One of the biggest thanks to this circuit is that it can adjust from 1.2v to 40v, being very useful.
The 100nF capacitor is used to eliminate noise and can be omitted if the regulator is placed near the power supply. The 4.7 ohms variable resistor can be an adjustable (adjustable with a screwdriver) or a potentiometer (more voluminous, but with a knob to adjust by hand). The output can directly feed a fan, or LEDs through resistance RL limitations. The value of RL will depend on the consumption of the LEDs and the supply voltage Vout. It can be calculated using Ohm’s law. U = RI
A practical example with a classic LED (which consumes about 10mA) and a Vin supply voltage of 12V. We have:
R = (12-3) / 0.01 (the value U with the regulator voltage drop is Vin – 3)
R = 900 Ohm (standard value of 820Ohm)
High-brightness LEDs, such as white or blue, usually consume much more, so a lower value for RL should be used. The idea is to try trying with just one LED. The value of the resistance can be revised a little smaller, but in this case, it will only be careful not to adjust the regulator on a voltage too strong.
As the LEDs are put in parallel, the intensities add up. Care should be taken not to exceed the limit of 1.5A of the LM 317. The idea is to stay below 1A to be sure.
The realization of the assembly can be done by directly welding the legs of the components together, or we can make a small printed circuit. There are two depending on whether we want to use an adjustable or a potentiometer. To realize the circuit, it will be enough to print the types than to oil the sheet to make it transparent (This technique works much better than the impression of the kinds on transparencies.Only oiled, it will be necessary to remove the excess with a cloth). Printing on a laser printer is recommended, but it also works with an inkjet (the ink is drooling on the paper but after only several months).
For this project, we will need the following:
- A multipurpose plate of electronics
- The resistance of 240 Ω
- 1kΩ potentiometer
- 0.1μF capacitor
- 1μF capacitor
- Transistor LM317
- Soldering iron and tin
- Various tools (screwdriver, pliers, pliers, etc.)
Observe the band on the Zener’s body. This indicates the side where the Zener cathode is located. Because the Zener diodes regulate the reverse voltage, you must connect the cathode with a positive voltage.
Turn on the unregulated power supply. Connect the positive and ground on the test plate.
Insert the Zener into the test plate. Then insert the 40-ohm resistor connecting to the Zener cathode. Connect the free (unused) end of the resistance to the positive connector of the unregulated power supply on the test plate. Connect the ground from the power supply to the Zener anode. Insert a long cable used the bridge and connect the anode of the Zener diode, use another cable and connect it to its cathode. For now, leave the other ends free of these cables.
Set the multimeter to read volts of direct current. Attach the positive lead of the multimeter (red) to the long jumper cable that comes from the Zener cathode, and the negative lead of the multimeter (black) attach it to the lead coming from the anode. Turn on the power supply. You must read a constant voltage of 12 volts.