Control012

                                          

Fading LED's
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Schematic design of Fading LED's
Part List :
Capacitors	Resistors
C1          =     1 μF / 63V Polyester C2          = 100 μF / 25V Electrolytic Semiconductors IC1         = LM358 Q1,2,4    = BC327 Q3,5,6    = BC337 Others SW1       = SPST miniature slider switch B1          = 9V PP3 Battery MISC      = Clip for PP3 Battery	R1,2              =   4K7 Ω ¼W R3                 =   22K Ω ¼W R4                 =    1M Ω ¼W R5                 =  2M2 Ω ¼W Carbon Trimmer R6,10,11,14,15=  10K Ω ¼W R7,8               =  47K Ω ¼W R9,13             =  27K Ω ¼W R12,16           =     56 Ω ¼W   Diodes D1-4              = 3mm or 5mm LED's                         (any type and color)
Notes
Two strips of LEDs fading in a complementary manner.  9V Battery-operated portable unit.  This circuit operates two LED strips in pulsing mode, i.e. one LED strip goes from off state, lights up gradually, then dims gradually, etc. while the other LED strip do the contrary. Each strip can be made up from 2 to 5 LEDs at 9V supply. The two Op-Amps contained into IC1 form a triangular wave generator. The rising and falling voltage obtained at pin #7 of IC1 drives two complementary circuits formed by a 10mA constant current source (Q1, Q2 and Q5, Q6) and driver transistor (Q3 and Q6). R4, R5 & C1 are the timing components: the total period can be varied changing their values. R7 & R8 vary the LEDs brightness.    For those whishing to avoid the use of trimmers, suggested values for a 9V supply are: R4      =  3M9 Ω ¼W R9,13  = 47K Ω ¼W R5      = Trimmers replaced by a short. Whishing to use a wall-plug transformer-supply instead of a 9V battery, you can supply the circuit at 12V, allowing the use of up to 6 LEDs per strip, or at 15V, allowing the use of up to 7 LEDs per strip. In this case, the value of the trimmers R7 & R8 should be changed to 100K Ω.

Source : Electronics Lab