Electronic holiday candle design

Brand AVX TPSE226M035R0125 Low impedance tantalum capacitor AVX 22

Electronic scale crystal oscillator 3.2*2.5mm 3225 16M (16.000MHZ) 12PF 10PPM 20PPM 30PPM

Probe domestic double-head probe 038-BB-5.7L The shape of the two ends of the needle is outside the pointed needle

As shown in the figure, the electronic holiday candle consists of a buck regulator source, a candlelight display, and a music blessing. The candlelight display consists of a clock generator, a ring counter and 21 light-emitting diode tubes as flames. The dual time base circuit ICla (1/2 556) and Rl, R2, and Cl form an astable multivibrator with an oscillation frequency of f=1.44/(R1+2R2)C1.
The oscillating frequency corresponding to the illustrated parameter is about 20 Hz. Its 5-pin output is used as the shift clock of the IC2 ring counter. CP.IC2 (CD4017) is a decimal counter/pulse splitter with its R end (15 feet) and 13 feet. Grounding, to form a ring counting circuit, each time a CP pulse, the counter is incremented once, so that the yellow LEDs (D9, D10), (D11, D12), (D13, D14), (D15, D16), (D17, D18), (D19, D20), and D21 sequentially emit light from the bottom to the top, thereby generating a flickering light perception of the candlelight from bottom to top. The D1-D4 and D5-D8 orange-red light-emitting two-plate tubes are connected to the center of the flame cone. It is directly controlled by the square wave of about 20 Hz generated by IC16. It is driven by the buffer stage VT1 and glitters, and is synchronized with 20Hz. In this way, the effect of the light candle is soft, swaying, and light and dark. D21 is located in the center of the light candle.
The music part is composed of a microphone, a high-pass amplifier, a voltage comparator, a one-shot delay, and an audio circuit. When someone blesses the air, the electret condenser microphone mounted near the flame picks up the mixed signal from bass to treble and adds it to the high-pass amplifier IC3b, which filters out the low-frequency noise and only allows The high-tone audio of 3000Hz Ul is filtered by a blow noise of about 50mV and amplified to a pulse of 5V amplitude, which is added to the inverting pin 2 of IC3a. IC3a is connected to the voltage comparator form, and the non-inverting terminal 3 is connected to the R7 and R8 voltage dividing points, and the reference voltage is about 4.5V. When the input spike is greater than. At 4.5V, the 1C3a output (1 pin) is low, and the lC1b one-shot circuit is triggered by the latter stage. 1Clb (1/2 556) and R9, C4 form a single-stability circuit, the delay time after triggering is td=1.1R9C4, and the single-stable pulse width given by the parameters in the figure is about 30 seconds. The square wave of the 9-pin output provides power to the music integrated IC4, allowing the IC4 to play a song of about 20 seconds. The music can be composed of "Happy Birthday to you", "Christmas Eve", "Wedding March" and other music, depending on the occasion and situation.