I asked about a month ago how to turn x amount of inputs into y inputs, and the answer was multiplexors. Someone said the way to use multiple multiplexors is to connect the same inputs to all of them, and then separate them by the active bit being "not"ed on one, and not "not"ed on the other. That connects two- and to use more requires "and" gates and so on. Anyway- I understand the schematic, and what logic to use in between these gates, but have no idea how to implement it. Can I purchase physical "not" and "and" gates? Or even pmos or nmos transistors individually that are big enough to work with? All the radioshacks around me are absolutely useless in terms of staff knowledge and part availability. So a link to an online store or article I could read of exactly how to physically implement these gates and where to purchase necessary parts would be greatly apreciated!
tl;dr: Where/Can I purchase or otherwise physically implement simple "not", "and", and "or" gates? Thanks!
If you have an arduino you can simulate any simple or not so simple logic functions in your software and use real input pins and output pins to show the results in realtime depending on the input pin conditions.
However if you just want to play around with real IC digital logic devices I would suggest using 74LS00 series of devices.
But yeah- as it will essentially be a chip selector bit allowing me to use a single output to multiply the actual number of outputs I have by 2 using multiplexors, it cannot be simulated by software. I need the actual output to differ physically using a single output. (lol was that a run-on sentence?)
Anyways, thanks again! That's exactly what I needed.
you can also make them out of transistors or diodes, for example I recently needed a 3 input and gate, that was done with 3 diodes and a pull up resistor, but I also needed 2, 4 input and gates which was ideal for the 4082 which is a dual quad input gate in a dip chip
You have two output pins and set then at opposite logic levels, or in fact what ever logic levels you like. You can do the cascading of many multiplexers like this.
Phildo,
Are you still working on the beer pong setup? http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1290040099
The SN74150, available at digikey, will let you read the state of 1 of 16 inputs.
If this uses too many pins, there are ways to overcome that.
btw
you can build anything (well any logic that is) just using NOR gates
Except tristate busses. And power-management. And non-volatile memory. And schmidt triggers... Depends how you define logic circuits!
I'd also like to say that these days TTL is obsolete, so avoid 74LS and other bipolar logic families in favour of CMOS (74HC, 4000 series). TTL actually takes power when its not switching, lots of power(*), and is limited to 5V.
(*) A 74LS00 (quad NAND) on 24/7 consumes about 700kJ a year quiescent (4.4mA @ 5V). Multiply that up for more realistic logic circuits ands its not trivial...
I'd also like to say that these days TTL is obsolete,
Not true, it is still made, you can still buy it. Therefore it is not obsolete.
It might have been superseded but that is not the same thing as obsolete. Any anyway it hasn't been superseded in all applications, that's why it is still used.
And in theory some of the 74xx00 functions didn't get continued on with the latest versions of this once dominant series. While many may not see a use for it these days the 74F181 4 bit alu function still has pretty good performance. Just don't try and use battery power. ;D
The 74181 performs these operations on two four bit operands generating a four bit result with carry in 22 nanoseconds. The 74S181 performs the same operations in 11 nanoseconds, while the 74F181 performs the operations in 7 nanoseconds (typical).
It still has it's place. In fact, you can now buy Single Gate packages. (...Something you could not do when these TTL chips were created... I mean, the goal was to cram as many as you could because you needed them).
Example: M74VHC1GT00DFT1G Single 2-input NAND gate in SOT-353 package.
Why is this good? With Micro-Controllers you might only need 1 maybe 2... and so there you go.
I use 74F3474s as shift registers (because I happen to have a small stash of them).
Good current drive for LEDs too.
Darn, down to my last 3, and 5 74F373s. Couple of 573, 574 left.
