Yesterday I prototyped a 4-comparator circuit with relay outputs. This circuit uses the internal reference voltage and comparators of the dot/bar LED display driver LM3914. A signal voltage, controlled by the potentiometer on the left, turns on one of ten comparators in order. The switch-to-ground output of the comparators is used to drive a pnp transistor, which amplifies the output current and drives relays. These relays can turn on LEDs, as shown.
The comparator outputs are grouped into 4 sets, such that one of four relays will switch, one after the other.
