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

[grunai]

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_luis]

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.

 

[chuckey]

What does it/ does not do? have you measured the +Vcc line?
Frank

 

[betwixt]

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.

 

[D.A.(Tony)Stewart]

If you want LiPO power, I suggest LCD instead for low current.
8x1 or similar
https://www.digikey.com/product-detail/en/VIM-878-DP-RC-S-LV/153-1115-ND/1118605
ATMEGA logic out are 25 Ohm drivers so no problem with 10 Ohm ESR LEDs at 2.2V FWIW...

and 1 ppm TCXO is only $1

 

[KlausST]

Hi,

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

Klaus