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Making process of Display drive unit of RCC

This board drives the 7 segment LEDs with the signal of the display control unit. The transistor arrays (TD62003) are mounted on in the sockets of the three upper left. The decoders for LED scan (74HC138) are mounted on two lower sockets Right side is 7805 and the heat sink which make +5V from a power supply. A heat sink is an aluminium board of 2mm thickness. It is satisfactory even if a heat sink is somewhat small. I made the space of the printed circuit board suit. This is the photograph of the wiring side. Many lines are wired to this board at the time of completion. The LED drive unit is attached in the back side of the display panel. The height on the back side of the display panel is limited to 15mm due to the height of the case. The interval with a panel is 5mm. The bunch of wiring cannot be made thick.