With the trend of multi-functionalization of mobile phones, the power consumption of mobile phones has gradually increased, which has increased the requirements for batteries. On the other hand, batteries have become smaller and smaller as the size of mobile phones has gradually decreased. The power supply technology has not been improved, which brings about the problem of reduced standby time, which brings a lot of trouble to people who use it frequently. In order to solve this problem, many people have adopted a dual-electric dual-charge configuration scheme when purchasing mobile phones to solve the problem of large power consumption. This not only increases the cost of mobile phone purchase, but also is not as convenient as it is supposed to be. It is not forgotten to carry the second battery or forget to charge the second battery, which makes the mobile phone's Normal use. In order to solve this problem, this article introduces a mobile phone emergency charger, which uses two alkaline batteries or rechargeable batteries. After the circuit is boosted, the mobile phone is charged by direct charging, and the normal use of the mobile phone is not affected when charging. Since the components used in the circuit are general-purpose components, they are not only low in cost but also simple to manufacture. Circuit working principle: Component selection and installation and commissioning: Emergency charger: In order to solve the problem of insufficient power supply for mobile phones, MP3, MP4 and other digital products, the emergency charger can be used as a power storage unit through a lithium battery, solar panel or hand-cranked ordinary AA dry battery. You can power or charge your mobile digital electronics anytime, anywhere, and on the go. Brought a lot of convenience to our lives! disposable electronic cigarette disposable vape pen disposable e-cig Shenzhen Xcool Vapor Technology Co.,Ltd , http://www.xcoolvapor.com
The circuit of the emergency charger is shown in the figure. It is a single-tube DC conversion circuit in the form of a single-ended flyback converter circuit. The so-called single-ended in the circuit means that the core of the high-frequency converter operates only on one side of the hysteresis loop. The so-called flyback means that when the switching transistor VT1 is turned on, the induced voltage of the primary winding Np of the high-frequency transformer T1 is 1 positive and 2 negative, and the rectifier diode VD3 is in an off state, and energy is stored in the primary coil. When the switch tube VT1 is turned off, the energy stored in the primary coil of the transformer T1 is filtered by VD3 rectification and capacitor C4 and output to the load.
The transistor VT1 is a switching power supply tube, and it is composed of a self-excited oscillation circuit with T1, R1, R2, and C2. After the input power is applied, the current flows through R1 to the base of VT1, turning VT1 on, and R1 is called the starting resistor. Once VT1 is turned on, the transformer primary winding Np is applied with an input voltage, its collector current Ic increases linearly in Np, and the feedback coil Nb generates a positive voltage of 3 positive and negative 4, so that VT1 is positively positive and the emission is extremely negative. The feedback voltage, which is injected into the base current through VT1 through C2 and R2, further increases the collector current of VT1, and the positive feedback generates an avalanche process, so that VT1 is saturated and turned on. During the VT1 saturation conduction, the primary winding Np of T1 stores magnetic energy.
At the same time, the induced voltage charges C2. As the C2 charging voltage increases, the VT1 base potential gradually becomes lower. When the base current change of VT1 cannot satisfy its saturation, VT1 exits the saturation region and enters the amplification region. When VT1 enters the amplification state, its collector current drops, and a negative voltage of 3 minus 4 positive is generated in the feedback coil Nb, so that the base current of VT1 is reduced, and the collector current is reduced accordingly, and the asymmetry occurs again after positive feedback. VT1 quickly expires. After VT1 is turned off, the energy stored in the transformer T1 is supplied to the load, and the negative voltage of 1 minus 2 positive generated by the primary winding Np is rectified and filtered by the diode VD3, and a DC voltage of 5.8 V is obtained at C4. Charge the phone with the phone's dedicated charging plug.
When VT1 is cut off, the DC power supply input voltage and the N, 4 and 4 positive voltages induced by Nb are reversely charged to C2 via R1 and R2, gradually increasing the base potential of VT1, causing it to be turned back on, and again flipped to reach saturation state. Repeat the oscillation in this way.
VD1, VD2, C3, etc. form a voltage stabilizing circuit. During the VT1 off period, the Nb-induced 3 negative and 4 positive voltages are charged to C3 via VD2, when the voltage on C3 (upper negative and positive) is greater than 6.2V. The Zener diode VD1 starts to shunt and reduces the base current of VT1, so that the collector current Ic of VT1 can be controlled to stabilize the output voltage.
It should be noted that since the input DC voltage is low, no isolation is required, and the input DC voltage dry and the output DC voltage are relatively close. Therefore, the high frequency transformer does not have a secondary coil, and the energy of the load circuit is directly obtained from the primary coil. There are two advantages to this: First, the conversion efficiency of the circuit is improved. Second, VD3, C4, and R4 form a surge voltage absorption loop, which absorbs the reverse high voltage generated by the VT1 cutoff moment.
VT1 requires Icm>1A, hEF is 50~100, 2SC2500, 2SD965, etc., VD1 is a steady-state two-plate tube with a regulated voltage of 6.2V. The parameters of other components are shown in the figure. The high-frequency transformer T1 should be self-made. With the ferrite core of E16, Np and Nb are wound around 16 turns with Φ0.44 enameled wire. When winding, pay attention to the starting end of each coil, do not make mistakes, so as to avoid the circuit can not vibrate. During assembly, a plastic film with a thickness of about 0.05 mm is placed between the two cores as a core air gap.