Digital clock main body

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Digital clock main board

"Two color automatic change displays digital clock kit" that purchased with 'Akizuki Denshi Tsusho Ltd.'(Sites in Japanese) for digital clock main board is being used. The kit that did a little reconstruction is being used.

	Circuit drawing
	Pattern drawing ( Reconstruction drawing )

I am carrying out about the following reconstruction.

	Stopping the oscillator( 50Hz is being output from the crystal oscillator of 12.8MHz ) on printed board and the input from the standard oscillator of the outside is made.
	The power supply for the use of clock ICs and the power supply for the use of displays are separated. For the use of clock ICs operate even the backup battery. The display does not display when the AC power is not supplied without backup. ( Due to the battery save )
	The clock circuit operates with only the battery when the AC power supply suspended. Also, the battery is charged when the AC power supply is normal.
	The voltage of 1Hz output is lowered for the use of the second display counters. Although the circuit of clock kit operates with 12V, the second display counter that makes it particularly operates with 5V. Therefore, The voltage of 1Hz output from the digital clock main board needs to be lowered.
	The flickering cycle of second display LED is done conversely. The count up timing of the clock is changed when the LED that displays second is lighted. ( Before reconstruction it counts up when LED is gone out. ) This reconstruction is not necessary if you don't want it. The adding 2SC1815 is used for this reconstruction.
	Second display LED is changed to 2 color display LED. AM or PM is being displayed with the red or green display in the kit. Red LED and green LED( It flickers every one second ) are using separately. I have changed them to a LED of 2 color( red and green ) display in one piece. Even this reconstruction is not necessary if you don't want it.