digital logic module questions

[Snaper]

Hi Guys,

I think this is the right place to ask.
I would like to create a digital logic module.
Really-really basic, just 7 ICs for the basic logics, AND, OR, NOT, NAND, NOR, XOR, XNOR.

My questions :

- 1 diode/input is enough protection?
- outputs protected with 1k resistor is enough?
- unused inputs to ground?

ICs :

4011
4071
4069
4011
4001
4070
4077

I know, maybe its a waste, but it is a one run board (home etch) only for my own hone experiments

[PHOBoS]

Diodes on inputs don't really have a function unless you're planning to connect it to something that has a
negative output voltage. Resistors (1K) on the outputs are useful as protection. are you adding LED's to
the outputs as well ? Connect inputs with a (100K) resistor to GND if you want to use them as inputs.

Although diodes on the inputs aren't really useful you can place them on outputs. This will create an OR-gate
together with the pulldown resistors on the inputs making it possible to connect multiple outputs to one input.
However if you're going for basic and are actually including an OR gate chip you might as well leave them out.

[synaesthesia]

If you want it to be even more basic, you could do it with just one IC per gate. Four switches on the inputs of half of a 4052 can be used to define a boolean function with two inputs. This way you could implement all the functions you listed, actually all that exist. If you use pull-up resistors and SPDT switches to both halfes of the 4052, you could have a function and its complement at the same time.

[Snaper]

[PHOBoS]

ah ok, I don't know what voltages buchla uses but in that case maybe 2 diodes on each input as protection
might not be a bad idea. A setup like this (ignore the opamp) where V- will be your GND connection or at least
whatever you connect the CMOS chips to. (best to use some schottky diodes)


100K pulldown resistors keep the inputs from floating and switching states when nothing is connected to it.

[Snaper]