This circuit offers a variety of Buck DC to DC converters. Because as circuit increase voltage as the USB 5v to 12v DC-DC step-up converter. This circuit is called a Boost converter circuit. The primary circuit is shown in Figure 1.
Basic of DC boost converter
According to the primary circuit, when the switch (S) Closed cause a voltage drop across L or Caused VL is an input power supply (Vin) has current at a coil, The rate of increase of the current is linear.
When (S) opened the current in the coil still flow to continue. Because of there current from the input source with the current of the coil. Makes current 2 supply current to a diode (D) Caused an output voltage higher than the input.
Figure 1 The basic circuit of DC to DC boost converter
While the switch opened the collapse of the electric field. Makes voltage of the inductance L to the left of a positive return is negative.so result is that the voltage between the input and the coil’s voltage has the same phase as the battery series (In-phase) the end result is Makes voltage of output increases.
How DC to DC boost converter works
The circuit. A structure is similar to the buck converters circuit. But when you want to design the output voltage rises to the switch is connected to ground. By virtue of the Booster. This means an increase of the voltage positioning device is D1, L1, they serve as the primary voltage converter circuit.
The switch we design both transistors Q1, Q2, serving each other feedback. The complete circuit is shown in Figure 2.
Figure 2 the complete circuit of the boost converter 5V to 12V has effective in the range of 77%
When the power supply to a transistor circuit T3 to the conduction system. Because it is the only one with a full bias current flows through R4 +5 volts to pin emitter to base. Through R3 to reach the potential removal of the input voltage.
The results of the transistor T3 has a bias, making it rise to Conduction provide current from emitter out to collector sent directly to the bias of base of transistor Q1 Makes T1 into conduction state to another.
T1 so is the switch (S). When viewed in circuit Figure 2. Making T1 conduct while L1 is connected to ground (or potentially negative light). Resulting voltage drop across L1 equal to the power supply voltage by the voltage of +5 volts L1 is connected to a positive voltage. And its bottom terminals is a negative voltage.
When T1 conduct causes the linearly current with coil L1, the current flow through the coil is the same as the collector current or the emitter current of T1. When the current of the coil will increase the voltage across R1 have value about 0.8-1.2 volts. Makes the transistor T2 conduct bias of T1 is to pull off.
Makes T1 as same switch open circuits. That is, L1 is cut out of the ground, the magnetic field of the inductor L1 and the voltage collapse occurred first. L1 is connected to the terminals voltage of the input voltage is negative. Serial-in phase with occurred voltage occurred the output is equal to +5 volts.
Vout = Vin+V
That is the voltage at the combined pass diode D1 to supply to the output. By has C1 value 10 microfarad power smoothing control.
To make the output voltage more or less depending on the period of energy. If a long period. Voltage happens to be very valuable. Because energy is concentrated there. This does not indicate that the low frequency of this circuit is to power up. Due regard to the resonance of the system. If the frequency is below the resonance box, it will not work the switching circuit.
But, however. This circuit is the regulator circuit controls the output voltage of 12 volts, thus adding to the Zener diode of 1 pcs. D2 No. ZPD12 which is the Zener voltage at 12 volts with the numeric suffix on the output voltage up to level 12 mA.
Makes the Zener diode current to return to the operating point of the transistor T2 T2. It changes according to the input voltage return it to eventually turn off transistor T1. T1 is the execution time of a shorter period. The solution is to give up control.
This circuit provides the output current of 20 mA and the maximum voltage of 12.6 volts while the input of 5 volts at the current of 64 mA that is effective in the range of 77% is not so bad.
Testing and Application
Since this circuit is very popular. so I tested them on real the universal PCB board. as Figure 3. I apply 5V dc regulator from this project to input and measure at the output is 11.50V or about 12V. And then I connected 12V LED to the output then measure current input is 40mA as Figure 4
Summing up this project worked surely
Figure 3 Test apply 5V input and we can get 12V output.
Figure 4 Measure current of this circuit
The components list
Q1, Q3: BC550 or BC549 or BC547, NPN transistor 0.4A 40V
Q3: BC560 or BC556 or BC558, PNP transistor 0.4A 40V
C1: 0.1uF 50V ceramic or Mylar capacitors
R1: 3.9Ω 0.25W resistors
R2: 470Ω 0.25W resistors
R3: 47K 0.25W resistors
R4,R5: 1K 0.25W resistors
D1: 1N4148, 75V 150mA Diodes
D2: 12V 0.5W Zener diode
L1: 100μH or 220 μH or 330μH, inductor how make it
and other parts
Also, 5V to 12V DC converter using
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