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Chess clock - can you point out errors in my design?

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grunai

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Hello!

I am planning to build my own chess clock based on Atmega8. I don't have experience in designing circuits so I would really appreciate your help in finding errors in my schematic.

Best regards,
grunai.

 

andre_teprom

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Component pins over wires, what is the reason to see some dots near to them.
Could simplify the schematic using GND net identifiers instead of connect all them.
 

betwixt

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Possible problems I can see:

Do you need pull-up resistors on PD0, PD2 and PD3? What voltage will be on the pins if the links are not fitted?
You can save components by using a 7805 regulator.
Your multiplexing needs to send 16 bits per pair of digits, 64 bits to display complete numbers, you may not get optimal speed or brightness from the LEDs.
The CD4094 outputs are only rated to sink 0.88mA so the LEDs will be very dim anyway.
Does the ATMEGA8 need an oscillator and reset signal?

Brian.
 

KlausST

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Hi,

place a 100n ceramic capacitor next to VCC and GND of each IC.

Klaus
 

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