In the figure, BG 1 and BG2 form a self-excited multivibrator, which generates short pulses, which are amplified by BG3 and BG4 composite pipes, so that the loudspeaker emits loud sound instead of firecrackers.
BG5, step-up transformer B 1, B2 and flash tube FT form a flash circuit, which emits corresponding flash with sound, making electronic firecrackers more vivid. The flash circuit consists of oscillating booster, rectifier charging, voltage indicator, pulse and flash tube.
Transistor BG5, feedback resistor R6, polyester capacitor C4 and oscillating booster transformer B 1 form an oscillating booster circuit, which is used to convert 6V DC low-voltage electricity into AC high-voltage electricity.
After turning on the power supply, the transistor BG5 began to vibrate rapidly, and the collector current increased, which made the magnetic core of the transformer B 1 gradually saturated, and the transistor BG5 turned off due to the interruption of the base current, and the magnetic flux of the magnetic core decreased accordingly. This repeated cycle will produce self-excited oscillation, which will make the transformer output AC high voltage above 300V after boosting. Because the oscillation frequency is in the audio range, you can hear a faint squeak from low to high.
The rectifier charging circuit is a constant voltage circuit, which is used for continuous flashing. The bridge full-wave rectifier circuit is used to charge the capacitor C5 to minimize the second flash interval. Transistors BG6 and BG7, bridge rectifier d1~ D4 and electrolytic capacitor C5 form a rectified constant voltage circuit. After the power supply is turned on, the BG5 lamp vibrates, but the charging voltage on C5 cannot make the neon lamp NL glow. Only when the voltage across C5 is charged to 250V can NL be turned on, making BG7 and BG6 turn on, BG5 turn off, and the oscillation circuit stops oscillating. When C5 discharges, the DC high voltage is lower than 250V, the neon bulb NL turns off, BG7 and BG6 turn off, BG5 automatically resumes oscillation, and the DC high voltage rises rapidly until the neon bulb NL turns on again. In this way, the DC high voltage will be kept constant automatically and repeatedly. The essence of constant voltage circuit is to add an automatic switch to the emitter junction of oscillator BG5.
Capacitor Cn], voltage dividing resistor Rn, trigger transformer Bz, trigger switch K2 and flash tube FT form a pulse trigger circuit. Flash tubes are cold cathode discharge tubes. A metal cathode and a metal anode are inserted into both ends of the straight pipe. The trigger electrode is wound around the outside of the glass tube near the cathode, and the outer surface of the glass tube is coated with a conductive layer of tin tetrachloride. The closed glass tube is filled with xenon, an inert gas with high luminous intensity. Under the action of high voltage electricity, xenon atoms lose electrons and become positive ions, and the electrons leaving the atoms gain energy, which ionizes the gas in the tube. Ions move in the electric field, making the gas in the tube "conductive". In this way, an external charge is introduced between the cathode and the anode, so that electrons and ions recombine, resulting in the release of energy in the form of light and gas discharge. When the xenon arc discharges, it shows an instantaneous intense flash.
When the rectifier diode charges the capacitor C5, it charges the capacitor Cn through the resistor R. When K2 is turned on, a high voltage of 8~ 10kv is induced in the secondary of the trigger transformer B2 to ionize the xenon in the flash tube and turn it on. The energy stored in the capacitor C5 is input into the lamp tube through the cathode and anode, so that xenon is discharged and dazzling white light is emitted. One-way SCR, resistor R5 and capacitor C3 are delay switching circuits, because it takes several seconds for capacitor C5 to charge to a constant voltage value after the flash circuit is turned on. If the power supply is turned on, the motor M rotates instantly, the resonant circuit oscillates by itself, and the speaker makes noise, which is out of sync with the flash lamp and loses the effect of acousto-optic concurrency. At present, the delay time of triggering SCR is equivalent to the delay time of C5 charging to a stable voltage, so that the motor M can rotate at the same time of acousto-optic, which can drive the series of guns to "ignite" and give people a realistic feeling.
Capacitor C6 and resistors R8, C7 and R9, C8 and R10 ... C. and Rn are set to provide trigger voltage to the primary of transformer B2 in time. If only one of C and R is set, continuous flashing cannot be realized, because it takes some time for C to charge to the voltage value required for triggering after discharge.
The number of C and R voltage dividing circuits is determined by the number of guns in series. In order to reduce the number of C and R voltage dividing circuits, series connection can be made into a ring.