Playing with logic - Page 1
Forum section: electronics / beginners

author: rthorntn
author_rank: Frequent Contributor
timestamp: May 28, 2018, 08:03:05 am
content: Hi,I have 10 x A and 10 x B of rlogic (https://www.kickstarter.com/projects/1953099853/rlogic-affordable-tiny-universal-logic)rLogic is any logic gate you want it to be simply be changing the location of a shunt (Jumper).Fairchild's NC7SV57/NC7SV58 TinyLogic was used (https://www.fairchildsemi.com/collateral/TinyLogic.pdf)I'm trying to figure out how do wire them and create a simple and fun test circuit.Why are there two pins for A, B, C & Y on each board and why is power on one end and ground on the other?I'm pretty new to all this stuff and I don't really understand the attached diagram.His example, a jumper across A and one of the PWR pins on an rLogic A board configures it to be an AND gate, while on an rLogic B board it's configured to a NAND gate. Then the gate inputs will be whichever two inputs are not tied, in this case those are B and C. This confuses me.Does rlogic have outputs, how would take 4 inputs (2 pairs) and put them in to 2 ANDs and then put the output of this in to an OR. Does the LED light if the logic is true, is there a pin where I can measure true?If it makes sense please point me in the right direction of arcane texts that will help me understand.Thanks for looking.CheersRichard

author: picandmix
author_rank: Frequent Contributor
timestamp: May 28, 2018, 09:04:05 am
content: Hi,If they are designed to teach you about digital circuits then they need to come with clear beginner instructions, otherwise whats the point of them ?Do you have any such instructions ? , you seem to say there are not any ?How many modules have you got ?Again no idea how much they cost, but think if I was looking to learn I would start with the very easy use and cheap DIP chips that can be simply plugged into a breadboard and used with leds or or whatever.There are masses of such circuits/info on the web about doing such basic experiments for fun.Here's just one of hundreds of ytube on such trainers.hth

author: Ian.M
author_rank: Super Contributor
timestamp: May 28, 2018, 10:42:33 am
content: Start with the datasheet for the gates used:http://www.mouser.com/ds/2/149/NC7SV58-196469.pdfwhich explains how they can be configured as a range of simple 2 input gates, and also the PCB layouts from the kickstarter project, which will let you trace from the jumpers to the inputs of the actual gates.The pin duplication at each end is so its easy to jumper any single one of the three inputs to either Vcc (PWR) for logic '1' or Gnd for logic '0'. It also lets you feed more than one gate from the Y output of the previous one - either daisychain using the pair of pins for each input or simply wire both using the pair of pins for the single Y output.What to do with them? Well there isn't a lot you can do because you've only got 10 of each type, the odds are you'd run out of one type before you'd used all of the other type, and they are only very basic two input gates. If you want one combination of four inputs to produce a specific output and all other combinations to produce an opposite output, that's three used up right there. A S-R flipflop would take two of them. A clocked J-K flipflop would take six of them.For comparison a 74HC138 can be used to select any single combo of four inputs to produce an active low output (and 74HC238 for active high output) and you can get several for a dollar.They *MAY* be useful to the Arduino maker scene - or at least that subset of it that are scared of breadboards, real components and even soldering - when they need to flip or combine signals to patch together interfacing some breakout board, but otherwise they are very much a toy.To figure out what to do with them, if you've got a windows PC, you may find Logic Friday useful. Its a GUI frontend for theEspresso logic minimizerThe original website's gone to domain parking, but it can still be accessed, including downloading the intaller,at the Internet Archive.

author: james_s
author_rank: Super Contributor
timestamp: May 28, 2018, 10:31:06 pm
content: At such an early stage I think logic gates are just as interesting to study in a simulator as with real hardware. This is one of my favorite beginner toolshttp://www.falstad.com/circuit/Once you start building more complex circuits then it's more fun to move on to a breadboard with real ICs.

author: Brumby
author_rank: Unknown
timestamp: May 30, 2018, 02:18:56 am
content: Quote from: rthorntn on May 28, 2018, 08:03:05 amI would expect anyone who has not had any experience with logic gates to be confused. By making these logic units "configurable" the very simple idea of what a logic gate does becomes buried in a mysterious bit of prestidigitation. I really do NOT like this sort of thing because there is a level of confusion introduced which has to be overcome before you can get on with, what is, some very basic circuit design. Just because something like thiscanbe done, doesn't mean it's a good idea.This is a better approach, IMHO...Quote from: james_s on May 28, 2018, 10:31:06 pm