The PB-502 Advanced Logic Design Trainer is a portable, robust instrument designed for the design and study of digital logic circuitry. It features selectable operating voltage allowing operation in either 5V TTL or 12V CMOS mode via jumper wire connection, with three integral fixed DC power supplies: ±12VDC @ 200mA (±5%) and 5VDC @ 250mA (±5%). The trainer includes a built-in clock with three fixed frequency levels (1 Hz, 1 kHz, 100 kHz, each ±20%), two fully debounced pushbuttons, eight logic switches, eight LED logic indicators, and a breadboarding area with 840 tie points and eight 25-pin power rails accommodating up to eight 14-pin ICs. Students can construct a wide variety of experiments including logic gates, combinational circuits, flip-flops, counters, decoders, encoders, and data conversion circuits, while learning hands-on breadboarding techniques and digital logic circuit analysis. The trainer is housed in a tough molded plastic carrying case with integral hinged cover for convenient storage and portability.