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This simple
and inexpensive circuit built around a popular CMOS hex inverter
IC CD4069UB offers four sequential switching outputs that may be
used to control 200 LEDs (50 LEDs per channel), driven directly
from mains supply. Input supply of 230V AC is rectified by the
bridge rectifiers D1 to D4. After fullwave rectification, the
average output voltage of about 6 volts is obtained across the
filter comprising capacitor C1 and resistor R5. This supply
energises IC CD4069UB.
All gates (N1-N6) of the inverter have been utilised here. Gates
N1 to N4 have been used to control four high voltage transistors
T1 to T4 (2N3440 or 2N3439) which in turn drive four channels of
50 LEDs each through current limiting resistors of 10-kilo-o Base
drive of transistors can be adjusted with the help of 10-kilo-ohm
pots provided in their paths. Remaining two gates (N5 and N6) form
a low frequency oscillator. The frequency of this oscillator can
be changed through pot VR1. When pot VR1 is adjusted To get the
best results, a low leakage, good quality capacitor must be used
for the timing capacitor C2
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