Steve,

I just remembered a difference between the breadboard and the perf-board circuits.

The LEDs on the breadboard were turned on by MCT6 opto-couplers which were connected to the shift out registers. The 22K resistor was after the MCT6.

The LEDs on the perf-board circuit are connected directly to the shift out registers, no opto-couplers.

The breadboard was used to learn how to shift out bits. This circuit will be used for one part of the application and requires the opto-couplers to isolate 2 circuits from each other.

The circuit on the perf-board is used for another circuit which just turns ON the proper LEDs depending on certain conditions, I'd like to avoid adding MCT6 chips there if possible. Finding the cause of that 'blinking' during shifting out might help me avoid a lot of chips and circuitry.

Robert