Single-channel flashing light string circuit (3)

It is a Shenlu flashing controller made of Suning integrated circuits. It can make the light string shake to strong,
slightly strong, weak light + turn off the light, strong light... h-type continuous flashing cycle, small and single withering flashing. , Tian this board is full of freshness
. And it has only two external terminals, which can be directly connected in series in the colorful light string circuit for convenient wiring
and use.
    In the figure, the thyristor VI and the diode symbols VD6---VD9 constitute the main circuit of the controller. The control network mainly consists of
six inverter Al (CD4069) and binary counter/distributor A2 (CD1017) digital integrated circuits and a few
discrete components. Vs, R and BA form a simple Li resistor step-down voltage stabilizing circuit, which outputs 2V DC power
to supply the control loop with power outage.
    The inverters I and u form an astable multivibrator, and the oscillation frequency is mainly composed of (RI, + R.) and c. Determined by the time
constant, the inverter II output terminal, that is, pin ④, inputs H
; Q9. This controller only uses four output terminals Ql-Q4
. When A2 is in the busy state, only Qo outputs high level , and the other output terminals are low-power. When
the CP terminal of A2 inputs a count During pulse, Q() becomes low level and Ql is high level; CP terminal inputs another
count pulse, Ql becomes low level and Q2 is high level; Cr terminal inputs a pulse again and Q2 becomes low level.
Level, Q3 is i high In level... When Q, i appears high In level, this high level is added to the busy end through VD-1, that is, the
@ pin, A2 is reset, Qo is high level, and the remaining outputs Both terminals return to low level. From the above analysis, it can be seen that
when the (I' terminal of A2 continuously inputs counting pulses, its output terminal Qo-w will cycle to high level. Its
cycle speed depends on the input pulse of CP terminal. frequency, the potentiometer RP can change the high-level cycle
rate of Qo~Q3.
    When oo is high level, the input terminal of the cycle inverter lU, i.e., pin @, is low level, and pin ⑩ after two inversions The output
is still low level, and the transistor VT gate has no trigger current H{ and is in the off state, so the colorful light string H does not light up.
When Ql is high, this high level passes through VD1 and R . Charge to L., and the voltage across C passes through R. and is added to
the input terminal of inverter III, which is the ⑩ pin of Al. When the voltage at [1] terminal rises to the value voltage Vt, t of the CMUS gate circuit
, The inverter III outputs low voltage, and then inverts the inverter IV to output a high level and adds it to
the gate of Vtr through R. V]I is inactive because it obtains the ifFi trigger voltage, and the light string I! is powered on. Emit light. When VT is turned on,
the negative electrode of VD5 is grounded, so VI)5 is conductive. At this time, the charge on G will be discharged through VD5 and VT, causing
the level of the @ pin of Al to drop. When it drops below V fRU^ The ⑩ pin of 1 suddenly changes to low level, and VT loses the trigger voltage and
turns off when the alternating current crosses zero. At this time, V'J- reverse bias is cut off, and the island level of Ql output can be determined by V[)l, R.
When the current reaches (1t), when (. The terminal voltage reaches v again,
the VT can be turned on again through two inversions of inverters III and IV. So within the half cycle of the alternating current, ( ; There is a process of charging and discharging, Cj charging
time, VT is off; C. When discharging, VT is on. G The shorter the charging time, the
longer VT is turned on during half cycle u, that is, the conduction angle The higher the voltage across the iL lamp F, the brighter the light. When Ql is high level
(1, the charging resistance is R? (iOOkfl), the charging resistance is the smallest, (1; the voltage at both ends reaches VTR earlier) , the brightness of the colored lamp
is maximum; when Q2 is high level, the charging resistance is slightly larger than R; ( iSOkn1, so the VT conduction angle is small, the brightness of
the colored lamp is slightly dim, Q3 is e, iLl usually, the maximum charging resistance is R ( 220kfl). The VT conduction angle is the smallest, and
the brightness of the colored lights is dim ; when QO is high level, the VT fluorescent light is off and the colored lights are extinguished. Therefore, the colored light string can cycle through the brightest, slightly
brighter, dimming and extinguishing modes.
    RP can use the WFIo type small synthetic carbon film lU positioner, and adjust the RP to change the cycle rate of brightness change of the colored lamp as desired . If it is found that the brightness change of the second gear is not obvious during use, the resistors R. and R
can be changed appropriately.
, and the resistance value of R, can satisfy the effect.