Building an LED Cribbage Board

[AT]

Well, as a hobby, I'm creating an electronic cribbage board. I want to have 242 (121 x 2) LEDs, and be able to select which one to light up (perhaps by pressing a button repeatedly).
While I am fairly astute with electronics, I am not yet any good with knowing where to start in a design.

Right now I'm wishing there was a simple programmable board with 121 outputs, but no such luck... Any ideas?

[tlbs101]

Use 5-bit shift registers for each group of 5. As you press the button, that single bit will just keep circulating around the 5-bit SR. This SR should drive a 5 CMOS inverters to sink current and be attached to the cathode of the each of the 5 Red LEDs -- each one in each of the groups of 24 (so each inverter output is connected to 25 LED's in parallel). Make sure that the inverters can sink 10- 20 mA. Put a resistor in series with each cathode-to-inverter output so the LED's don't see too much voltage.

For each different group-of-5, use larger SR's to total 25 bits (each bit representing a group of 5) Each sucessive group of 5 LEDs will be enabled based on the larger SR. In this case all of the LED anodes in a group of 5 should be tied together, and each output of the 25-bit SR should be connected to one group common anode. Make sure that the SR can drive 10 - 20 mA.

Make the final LED a green one and use the last bit of the 25-bit SR and the first bit of the 5-bit SR to drive it, similar to the others.

Add a reset button.

Be sure you de-bounce the push-button switches heavily (in time) so you don't have to keep resetting and starting over if an extra point is accidentally made.

[Wally]

but you've got to be able to turn off all LEDs in each group of 5 as you advance down the board. Will your design allow for this?

[Enzp]

You should be able to just daisy chain a pile of SRs in series and clock the lit LED through the row of them. Tie all the resets or loads together

Alternatively, though more complex, you could matrix the LEDs and just run a counter with enough bits to count to 121 (128 - 0 to 127) A bit of logic to get from counter to matrix.

The guys at the electronics hobby sites would of course instantly tell you to use a PIC. Then you could get fancy and have a keypad to enter numbers instead of hitting a button 16 times.