Picking out the correct logic gates

[jozer]

About a year ago, for one of my computer science classes, I was tasked a bit shifter for a computer. I was provided with several ICs; NAND, AND, OR, and NOR gates; wire cutters; wires; a breadboard; a 6v battery; and some LEDs.

I absolutely loved the assignment and now want to pursue electronics as a hobby. Next I want to build an ALU. I was looking at Jameco.com and was immediately overwhelmed by the sheer number of different types of gates available - there was not just one AND gate available but several.

I am coming here for a little help regarding which gates I should purchase. Which NAND, AND, OR, and NOR gates go together? Or is any combination acceptable?

Additionally, I was wondering what power source would be appropriate to use with these gates. I do not want to accidentally short-circuit them.

Lastly, although it would clearly depend upon the voltage of the source, would the impedance of the gates protect them from the current, or would I need to place resistors before the gates?

Thank you all so much.

 

[ronv]

Welcome!

There are a ton of options, but you may want to pick a logic family to use. Here are my thoughts:
If you want flexibility for power supply voltage look at the CD4000 family.
For a wide selection of parts (you may find an ALU in a chip) look at the HC & HCT family.
A small 5 volt supply would work for both. They will only take the current they need to operate.
Last, the inputs should be between ground and the power supply voltage. No resistors needed.

 

[ljcox]

I have a ttached a paper that will introduce you to digital logic.

I wrote it some years ago - based on one written years earlier by a work college - Norm McLeod.

Note that he used High & Low rather than 1 & 0 since the latter are confusing.

In the case of positive logic, 1 = H & 0 = L.

But it is vice versa for negative logic.

Whereas, H & L depend upon the internal design of the gate & are not affected by + or - logic.

 

[KeepItSimpleStupid]

Way back when you learn that you can build anything from a NAND gates. For instance, take a 2 input NAND gate and short both inputs. You now have an inverter.

 

[crutschow]

Here's a good listing for CD4000 series CMOS logic chips. They are a good rugged logic family that work over a wide voltage range as long as you don't need high frequency operation (above a few MHz).

 

[alec_t]

Logic circuits in the (generally outmoded) TTL family are built using bipolar transistor technology. Most other families use CMOS FET technology. The main advantage of CMOS is that it is much less power hungry than TTL; the main disadvantage is that it is much more easily damaged by static electricity.