Wind it up directly with an electric mosquito swatter, haha
There is only one set of voltage doubling circuits inside, which is usually d 'about 400 V.
Remove the one in the red box in the picture above and pull the leads from both ends of the capacitor into the green box, which is the output voltage. It's good to play.
Schematic diagram of 18650 single-cell battery charge and discharge protection circuit
The picture above is the schematic diagram of the charger, and the principle of operation is presented below.
1. Constant current, voltage limitation, charging circuit. This part is made up of components such as 02, R6, R8, ZD2, R9, R10 and R13. When the mains is connected, an alternating voltage is induced at the secondary of switching transformer T1. After rectification and filtering by D4 and C4, it provides a direct voltage of approximately 12.5 V. A chemin forms a loop through R6, R1l, R14, LED3 (FuL saturation indicator) and R15 LED3 lights up, indicating the state of charge: the voltage of the other path is current limited via R8, stabilized by ZD2 (5V1), then connected in parallel by R9, R10 and R13 divide the voltage to provide bias to the Q2b pole, so that Q2 is in a conduction precharge state. The constant current source mechanism consists of Q2, its base voltage division resistor, ZD2 and other components. When the battery to be charged is installed, the voltage of 12.5 V is current limited via R6 and the battery is charged with a constant current via the c-e poles of Q2. At present, Ul (Ul is an unknown software package IC model) is connected in parallel with R6. The voltage drop at both ends of R6 causes the potential of pin ① to be higher than that of pin ③, and pin ② produces about two negative pulses per secnde.
Flash LED2 (CH charging light) frequently to indicate that it is charging normally. As the voltage across the charged battery gradually increases, that is, the potential of the e pole of Q2 increases when it reaches the set voltage limit value (4.25 V), since the potential of pole b of Q2 remains. unchanged, Q2 goes to cutoff and charging ends. At this time, pole Q2c floats, pin ③ of Ul is high potential, pin ② of U1 outputs high, and LED2 turns off. At this point the current is limited by R6, R11 and R14 to charge the battery and light up LED3. LED3 serves as a triple indication of charging, saturation and trickle charging.
2. Polarity identification circuit. This part is made up of R12 and LEDl (red TEST polarity indicator). The protection circuit is composed of components such as Q3 and R7. Suppose the polarity of the battery being charged is reverseee.
LED1 lights up on the positive side, warning that switch K needs to be switched to allow normal charging. If the battery is connected in reverse, pole I) of Q3 will be positively biased through R7, Q3 will be activated and the potential of pole B of Q2 will be lowered, shorted and cut off, blocking the current. output (otherwise the battery will be reverse charged and discarded). This protects the safety of the battery and charger.
Working principle:
After connecting the charger to the mobile phone and the socket, the voltage is adjusted through the resistance and enters the voltage comparator with a small value, and the output rated value A is the normal charging of the phone. When the mobile phone is fully charged, a voltage higher than the voltage at the other end enters the voltage comparator and produces 0V. At this time, the relay attracts the armature and breaks the circuit. Turn on to rperform automatic power off.