LED pattern flasher uses ripple counter

This circuit uses the pulse outputs of a ripple counter to produce various patterns of LED flashing, depending on which counter outputs are selected. IC1 is a CMOS 4060B 14-stage ripple counter with internal oscillator. Two of its outputs are fed to separate diode pump circuits to drive LED1. As shown, the circuit will give a one-two-three, one-two-three flash sequence. Additional outputs can be connected by duplicating the circuits shown.

Referring to diodes D1 & D3, the diode coupling circuits work as follows. Each time the "8" output of the counter goes high, the leading edge of the pulse is coupled via a 10mF capacitor and diode D3 to LED1. When the "8" output goes low, the 10mF capacitor is discharged back into that output via diode D1, ready for the next pulse leading edge.

If you want to work out the flashing pattern of the LED, consider selected pulse outputs as a sequence of binary numbers. For example, if two adjacent outputs are used, IC1 generates the following binary sequence: 00 01 10 11 00

This produces one leading edge from 00 to 01, another from 01 to 10 and another from 10 to 11. However, there is no leading edge from 11 to 00. This creates a one-two-three flash sequence.

The flash frequency can be altered by changing the timing components and is given by the formula f = 1/
(2.2 x R1 x C1), which is divided by the number of stages of IC1. LED1 should ideally be an ultra-bright LED, while the brightness of the flash can be varied by changing the capacitor value. The current drain is around 3mA.