Blinking Arrow

17 LEDs in four groups bar-mode sequence

Suitable for shop-windows animation etc.

Circuit diagram:

Blinking Arrow


R1_____________500K  1/2W Trimmer
R2______________22K  1/4W Resistor
R3,R4,R5,R6______4K7 1/4W Resistors
R7,R8,R9_______470R  1/4W Resistors
R10____________270R  1/4W Resistor

C1_______________4µ7  25V Electrolytic Capacitor
C2_____________220µF  25V Electrolytic Capacitor

D1--D17________LEDs   Any type and color (except blue and white, see Notes)

Q1,Q2,Q3,Q4___BC337   45V 800mA NPN Transistor

IC1____________4093   Quad 2 input Schmitt NAND Gate IC
IC2____________4520   Dual binary up-counter IC
IC3____________4094   8-stage shift-and-store bus register IC


A blinking arrow can be a very attractive gadget, suitable for many indication purposes. This circuit provides a bar-mode sequencer driving 17 LEDs arranged in four groups in order to build-up a bright arrow. When the build-up of the arrow is completed, all LEDs stay on for some time, then off for the same time-delay and then the cycle restarts. Sequence speed can be set by R1.
For those wishing to experiment, sequence timings can also be varied by connecting pin #5 of IC1B to pin #5 of IC2 and pins #6, 8 and 9 of IC1 to pin #6 of IC2. Other pin combinations are possibile by shifting the above named pins of IC1 to higher outputs of the counters contained in IC2, i.e. pins #6 and 11, pins #11 and 12 etc.
The resulting effect of the original four groups of 17 LEDs arrangement is shown in the title heading.