Abstract
Seiichi Nakamori
This paper newly designs the control circuit of the 7-segment common cathode LED display global positioning system (GPS) receiver clock and presents an Arduino sample program. The computer numerical control (CNC) router engraves the copper foil substrate to manufacture the printed wiring boards (PWBs) of the 7-segment common cathode LED display and its control circuits according to each G-code produced by the printed circuit board (PCB) design software Target3001! For each segment of the 7-segment common cathode LED display circuit, the two LEDs are connected in series. From an experiment, the two N-Channel metal-oxidesemiconductor field-effect transistors (MOSFETs) EKI04047, one at the high side and the other at the low side around the two LEDs, do not light on the two LEDs connected in series at all, unlike the case of the two LEDs connected in parallel. For this reason, upon lighting on/off the LEDs, this paper, newly, proposes the switching on/off control circuit with the optical relays at the high and low sides around the two LEDs connected in series.
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