Logic Gate Display - Page 1
Forum section: electronics / beginners

author: Manteiga
author_rank: Newbie
timestamp: November 08, 2014, 12:42:32 pm
content: Dear All,Firstly, I am not an electronics expert, so please forgive any stupidity on my behalf. However, I am trying to create a large scale interactive display of what logic gates do.For example, I wish to make an AND gate with rope lights representing the lines for input and output, and when the inputs are activated using buttons the output rope light will be lit.I plan to repeat this process for a range of logic gates (AND, NAND, OR, NOR, XOR, XNOR, NOT). Basically the physical version will look a lot like thishttp://www.neuroproductions.be/logic-lab/in their logic gate example at the bottom of the page.So far, I have a plan of purchasing an Arduino Uno and a MUX Shield. I would then connect each switch to the to MUX shield in a row of inputs (about 16 in total). I would then use a MOSFET to control each of the lights to 2 rows on outputs (about 20 to start with). Then I would write a program to control the LED rope lights, dependant upon the inputs (not too scared about that bit).However, I have looked at the cost of this, and as a little project the cost starts to spiral, particularly with the number of MOSFETs this would require. Is this a sensible way of going about this project or is there something obvious that I am missing?I hope I have made myself clear. Thanks in advance for your advice.

author: Psi
author_rank: Super Contributor
timestamp: November 08, 2014, 12:52:24 pm
content: What do you consider expensive?Also what current do these rope lights require.Are you're looking at prices from your local electronic store? They're usually quite expensive.A generic mosfet might cost $8-$20 from my local jaycar electroncis store but only 50c from digikey.

author: Manteiga
author_rank: Newbie
timestamp: November 08, 2014, 01:11:41 pm
content: Thanks for taking the time to respond.I would like to get the project to not much more than £100 in total (this excludes the mounting board, and cost of the buttons). The MOSFETS I was looking at were about £1 each, but needing so many, pushes the overall cost up a bit much. Not really sure where the best place to purchase them from, just looking at Digikey at the moment (they do look cheaper there) but so many different types I am not sure what I would be getting.The rope lights are 12v.

author: Tandy
author_rank: Frequent Contributor
timestamp: November 08, 2014, 10:29:27 pm
content: What is the current requirement for the rope light? You might be able to use a darlington driver like theULN2003

author: SL4P
author_rank: Super Contributor
timestamp: November 09, 2014, 07:47:53 am
content: Quote from: Manteiga on November 08, 2014, 12:42:32 pmNot sure of your issue exactly. To implementboththose interactive examples would require around 30 drivers total - perhaps pumped from a shift-register arrangement to simplify the wiring and reduce processor pins. Buttons in a similar manner.This number of drivers could be reduced further by multiplexing the ropelight supplies.Arduino clone $20 max. Buttons (30 @ 0.50 each = $15max) Rope lights $tba Drivers and assembly (30x $2 = $60 max)Time is the variable, and only you can see what is needed. So $95 plus rope-light and your time - say a solid weekend.The code is completely separate, but it looks like you know what you're doing there.

author: tautech
author_rank: Super Contributor
timestamp: November 09, 2014, 12:41:01 pm
content: Not to rain on your parade, just to offer another old site that you may or may not have found:http://tams-www.informatik.uni-hamburg.de/applets/hades/webdemos/10-gates/00-gates/and.html

author: Manteiga
author_rank: Newbie
timestamp: November 09, 2014, 08:27:23 pm
content: The rope light I was thinking something like this.http://www.ebay.co.uk/itm/New-Blue-5M-Waterproof-300-LED-3528-SMD-Flexible-LED-Light-Lamp-Strip-12V/221521102729?_trksid=p2054897.c100204.m3164&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20140407115239%26meid%3Dda3f5925a09c48f1a2e7972a5c200863%26pid%3D100204%26prg%3D20140407115239%26rk%3D7%26rkt%3D30%26sd%3D191166244738I guess it is clearer in my mind what I am going to do. I think for now I am going to drop the half adder concept and just start with the logic gates.I am going to spend a little time researching the right type of MOSFET at the right price.Thanks again for your help everybody.

author: SL4P
author_rank: Super Contributor
timestamp: November 09, 2014, 10:02:50 pm
content: Just one last aside... 300 LEDs / 5m LED strip.Assuming each piece you'll use in the display is - say 6-inches long. (150mm)Each logic I/O 'pin' will have around 8-9 LEDs (allowing for cutoff etc)16mm pitch == step back to see the big picture.I s'pose that's a reasonable length and density of LEDs for room-sized viewing..But why blue? No relevance in electronics / logic notation that I'm aware of.Idea sounds great, but I reckon you need to step back and identify your requirements - then start designing, rather than the other way around.