Automated Crib Lights

Low supply (12V) for children safety

Fully protected outputs

Circuit diagram:

Automated Crib Lights circuit diagram


R1___________150K  1/4W Resistor
R2,R9,R14_____22K  1/4W Resistors
R3,R11_______220K  1/4W Resistors
R4,R12________10K  1/4W Resistors
R5___________100K  1/2W Trimmer Cermet
R6,R7,R13,R15__1R  1/4W Resistors
R8____________33K  1/4W Resistor
R10__________270K  1/4W Resistor
R16___________47R  1/4W Resistor

C1,C4________100nF  63V Polyester Capacitors
C2,C6_________10µF  25V Electrolytic Capacitors
C3,C5________100µF  25V Electrolytic Capacitors

D1-D3_______1N4148  75V 150mA Diodes

IC1___________4060  14 stage ripple counter and oscillator IC
IC2__________LM324  Low power Quad Op-Amp IC
IC3__________78L12  12V 100mA Voltage regulator IC

Q1,Q3,Q5_____BC238  25V 100mA NPN Transistors
Q2,Q4,Q6_____BD681  100V 4A NPN Darlington Transistors

J1___________Miniature input socket,
             suited for commercial plug-in variable voltage power supplies 
J2-J5________Two ways output sockets

Device purpose:

This circuit is intended to drive the various lights decorating the crib prepared during Christmas season at many homes in Latin Countries, especially for children delight, in order to obtain realistic light-effects.


Load requirements:

Circuit operation:

IC1 oscillates at a frequency calculated to obtain a pin 2 level change around every minute. IC2A is then enabled to slowly charge and discharge C5 through R10 during a 2 minutes period. IC1 pin 9 drives D2, R3 & C4, generating a sawtooth for IC2C & IC2D comparators. IC2D comparing the voltage at pin 13 with the sawtooth, generates a squarewave with variable mark-space ratio driving the output darlington Q2 for daylight bulbs. IC2B changes its output at a threshold voltage settled by R8 & R9, activating IC2C & Q4 that act like IC2D & Q2 driving model-houses bulbs as evening approaches and turning them off at dawn. R11 & C6 provide slow turn on and off and R5 sets the basic brightness of these bulbs. IC1 pin 7 drives the output darlington Q6 for flickering fires bulbs and R16 prevents them to turn off completely for a more realistic effect. Q1, Q3, Q5 and associated Base resistors provide current limiting.