### diode logic

I'm making a giant adding machine using only resistors(miscellaneous), switches SPST (for input) LEDs (for display) and diodes(for logic). NO TRANSISTORS I have it so that it can recognize 0,1,2,3,4,5,6,7,8,9, but if it recognizes 8, then it recognizes it as all the other numbers. If it recognizes 0, it recognize 1, and 7. If it recognizes 6 it recognizes 1, and 5. If it recognize 9 it also recognize 7. If it recognizes 3, it also recognizes 7. basically if you take a 7 segment display, any number on it, it'll recognize all the numbers in the number. I need help sorting it ou so that if it recognizes 8, it only recognizes 8. If it recognizes 3, it only recognizes 3. Etc...

Topic by guyfrom7up   |  last reply

### Relay Logic

I have a fetish for antiquated technology. Stuff like vacuum tubes, transistors, electro mechanical devices, and of course relays used to run things. I did a few searches here on Instructables on relay logic and found nothing so I thought I'd start a forum on it.  Most of the earliest computers ran using relays. I love how they sound, clickity - clack. In a way they seem more alive to me than todays silent electronics, and dead boxes, There's just something cool about a machine that you can hear working instead of dead silence, maybe I'm just a old fashioned.  Anyway, I have a limited knowledge using relays for adders, if, and, or, gates, etc. but I'd like to learn more. I did however make a clock circuit using only relays and capacitors, and I have a video of it here... http://www.youtube.com/watch?v=Ya5R7EqF8vk I based that circuit (after lots of pondering and experimentation) on the clock in this relay computer here. http://www.youtube.com/watch?v=n3wPBcmSb2U My relay clock was really unstable and would stop by itself quite a bit. I'd like to figure out how to make it more stable. Also, I'd like to do some more experiments... Anybody else have any interest in this subject? Or have any experience making small bit relay computers, or relay control systems for robots, etc? By the way here's some other cool relay run computers and stuff. Another Relay computer http://www.youtube.com/watch?v=O-omFP_G57U&feature;=related Relay counter thing. http://www.youtube.com/watch?v=YQ4ynGxQnGY Mechanical pong game - run on relays http://cyberniklas.de/pongmechanik/indexen.html

Topic by bart245   |  last reply

### simple logic circuit

Uuhhh..I'm not really sure about this..i'm an electronics engineering studentand my instructor in Logic Circuit and Switching Theory requires us to make a project which will include logic gates.now i searched in the net for some ideas i found two..but i know i shouldn't copy their projects..can anyone help me?link2link1thanks guys!

Topic by hazelcharisse   |  last reply

### Control Logic with PWM? Answered

I am currently working on a robotics project, and need a bit of help. I have this H bridge, and would need to control it via PWM. Speed control isn't necessarily what i need, though i wouldn't mind. (In4 i should have just bought an ESC) The whole bot is controlled by PWM (All servos) except for the two DC motors that i have on it -- One for forward and backward, and another for rotating an arm. How would i control the H Bridge with PWM? Which pins would i connect what to?

Question by RocketPenguin   |  last reply

### Logic circuit to generate and convert 3 bits parallel binary code into series for subsequent transmission ? Answered

A project I am working on has 6 water sensors placed at different altitudes inside a tank.I've developed a circuit to assign 3 bit binary codes to each of the sensor and then transmit it wirelessly.I've attached the truth table and the binary functions that yield the desired output, as a picture.Please refer to it and check if it looks alright to you.Keep in mind that the sensors output '0' (ground) when idle and '1' (Positive) when active.  Also, the sensors are so placed that sensor 2 won't get activated unless sensor 1 is activated ,sensor 3 unless sensor 2 is activated and so on..I.e,when the sixth (last) sensor is activated ,all the other sensors would be active too.So,the truth table contains just the possible combinations. A,B,C,D,E and F are the sensors(bottom to top) X,Y and Z will be fed into a binary encoder ic,whose output will be transmitted. Surfing the web,I realised that logical high and low can also be set using pull up and pull down resistors .I would appreciate it if someone could enlighten me on how this is done.(Explaining with reference to my circuit will be the best way)

### Logic gate set up with basic principal of "A is I: B is I for 1 click, then O//A is O: B is I for 1 click, then O"?

I've been looking about for awhile now for a solution to this little puzzle I've managed to get myself into. I know the question may have failed to be a proper logical statement, but basically, this is what I need: When input a is on, output b will toggle on for one second, then toggle off. When input a then goes off, output b will then toggle on for one second, then off. Basically, when the input state changes, the output will go on for a second, then off. I know the opposite can be done (that is, one second input toggles a on output, or visa vers) with flip-flops, but doing this is a bit outside my realm. Any help would be fantastic! Thanks in advance!

Question by DoctorWoo   |  last reply

### project

Can anyone help me give a simple project using logic gates...

Topic by ferdel

### Logic signal conditioning question?

I a robot i am building, i need to condition the signal as follows with any Microcontroller, only logic gates If 1 is high then  A & C should be high If 2 is high then  B & D should be high If 3 is high then  A & D should be high If 4 is high then  B & C should be high Where 1,2,3&4 are inputs and A,B,C,D are outputs No two inputs will be high a t the same time

Question by qwerty156   |  last reply

### Need help with state transition table and diagram

I need to make a sequential circuit which output will used for my combinational circuit input. I already made my combinational circuit which gives output in 7 segment display. I need to show EC1013 in & segment.The binary to show them is given below. 000=E 001=C 010=1 011=0 100=3 You can see I need to show EC1013 where 1 is repeated again..thats why I am unable to figure out the state  transition diagram for that... I tried to simply make the state transition table according to my output  and used K-map to minimize that and build that circuit..but it stucks in the 10 loop.. after showing EC10 it keeps on showing 10101010 forever.can some one help me with that

Question by TanvirM1   |  last reply

### Cheapest DIP glue logic?

I am looking to by some glue logic chips to prototype in so they must be in dip packages. I also want them to be cmos chips and not ttl. I am looking for which family of logic is the cheapest and for a good place to by them on the cheap. I don't care about the specs that much in terms of speed by I would hope for 5V and the ability to supply 15mA or more. The reason I am asking instead of finding the answers for myself is that I have already tried looking but there seem to be so many families that are very similar and I cant come to a conclusion. Ii was hoping that somebody who had some experience working with them would have some insight into me question.

Question by seanroberts   |  last reply

### Logic Gate Help Needed Answered

I am building a Binary to Decimal converter and i need help making a flawless AND gate from bipolar-junction transistors. If someone could Send me a link or email me some schematics, I would greatly appreciate it. If you do email the schematics please make sure they are compatible with Eagle. I don't want to use a converter chip because it takes away the fun of the project for me. I have tried all of the common types of AND gate configurations using NPN's (C-fwd B-in E-collect, C-in B-fwd E-Base, Etc.).

Question by toast5678   |  last reply

### Problems with logic(NAND) gates? Answered

I MADE a circuit that basically detects when an IR beam  is cut using a LM741 opamp .AS shown in the schematic i've connected the output of the opamp to the  two transistors (which is a nand gate) ,so when the beam is cut the output of the transistors should be high but instead the led at the collecter of the transistor glows only brighter. should i use a nand gate in a DIP package ?also when i individually measured the output of the opamp it showed that there was constantly 1.5 v coming out i tried measuring it with both opposite polarity leads of the multimeter  ,still  it showed a 1.5 v output,why does this  happen?PLS help.i need it fast.

Question by Strontium   |  last reply

### Need suggestion in digital logic design semester project.

I need suggestion in digital logic design semester project,with use of gated ICs multiplexer etc.

Question by szafar2   |  last reply

### What do i use for an &quot;if then else&quot; gate? Transistor logic instrucions would be best but anything that works is fine. Answered

What do i use for an "if then else" gate? Transistor logic instrucions would be best but anything that works is fine.

Question by cdarcy   |  last reply

### Oscillator with AND and NOT gates? Answered

Hi, I've been recently working with logic gates and that's when this struck me.If an AND gate and an inverter are hooked up as per the attached schematic, can point A function as an oscillator?Assume that the gate inputs float high. If so 1)What would be the frequencies of the oscillations if the gates used are a)CMOS b)TTL ? 2)Would the frequency change with the input voltage ? 3)Is this implemented elsewhere? Thank you for reading my question.

### Can someone provide the schematic for a 2 input TTL OR Gate with Totem Pole Output?

I have for some weeks been researching to find the schematic for a 2 input TTL OR Gate with Totem Pole Output (versus the Open Collector variety).  However, I have had little success in finding the schematic.  It was suggested that I try the Forum to resolve my problem.  Therefore, can someone either provide a reference that shows the schematic or draw one?  Thanks.

Question by ElectroZapper   |  last reply

### Levelshifting 3->5V. Can I add a DC bias of 0.5v or so to the 5v input line to bring up the 3v signals?

Assuming it doesn't just line up correctly, eg: If my Vih is 3.6v on the 5v side, and my Voh is 3.3v on the 3v side. By DC bias I mean connecting up a voltage divider giving 0.5v to the line connecting the 3v->5v. I'm guessing this isn't done as it would drain power when the 3v line goes low, but if the divider is high enough resistance, that could be minimal?

Question by quatch   |  last reply

### NPN to PNP control? Answered

So as I get into this project the circuit keeps building and now I once again have another problem that I can't figure out. As the title hopefully suggests I am using a NPN PN2222A trans. to control a PNP 2N3906 The idea was to use the 5v from a Ardinuo UNO to control a 12v. Currently I am testing with a 9v I had on hand. I thought it would pretty straight forward but every time I supply power to the NPN it creates the short needed to turn on the LED, but once I cut the power the LED stays on until I create another short (using a probe) uphill of the NPN. The only thing I can think of is that the LED doesn't the resistance needed for the power to re-saturated the PNP. Any thoughts? I will admit  haven't done any of the math needed yet for the resistors. Also can someone send me a link to the programs you use for drawing the layouts so I can move past MSpaint?

Question by Jayccob   |  last reply

### Would this work as an XOR logic gate? Answered

Hi, I'm new to logic gates and I am wondering if this would work as (or is) a XOR logic gate.

Question by josh1324   |  last reply

Hi everyone,                  I was planning to make a doorbell of which's switch is a touch pad.I tried understanding the logic behind the touch screens used in i phones and such otherd but they seem a bit complicated.Another solution I got was a circuit which has two free wires and when a person touches the two wires(creating contact),the load gets power.This is based on transistor switching.But I don't want to adopt this design since........ I don't know for some reason.Then I remembered those classy electrical testers(seen in the picture).They have a neon bulb in them which glows when they get a voltage of certain range from one end and our body is used as ground when the other end is touched.So if I use this mechanism I just have to use the setting to power the load when a metal plate connected to one end is touched by a 'user'and a voltage is given through the other end.I know these things usually have a neon bulb as they handle AC voltage.Finally here's what I actually need to know- Is it possible to build such a circuit where a 12 VDC is supplied to one end and the load is given power when the other end meets ground(here the person touching the pad).Maybe this might be a total jabberwocky but anyway contribute your valuable suggestions.If anyone has seen such circuits elsewhere, a schematic could be really helpful.Thank you in advance.

### Digital or analog clock with logic gates

Hi everyone I want to help you. Our teacher wants us to do digital or analog clock only through logic gates and we have no idea please need help thank you

Question by Mehmet Ömer Ceylan

### Cool Tool - Basic Stamp Logic Analyzer

A month or so ago Parallax had their basic stamp logic analyzer on sale for \$30, so I picked it up. Its a slick little tool . It is handy to use when testing your wiring and software. If you have a BS2 and see it on sale again over at Parallax check it out. The only downside is the software is windows only, so mac geeks like myself will have to use a VM. -Joe

Topic by joe   |  last reply

### 90 degree turn of a line follower robot

I want a line follower to follow this track and when it comes back to the start point i want it to take the path of the starting point again not the forward path and so on . ONLY BY USING LOGIC GATES ( no micro-controller, Arduino..etc )

Question by superdz   |  last reply

### Transistor NAND Gate does not completely work.?

I have been trying out some logic gates using transistors and I am confused already. I have built a NAND gate using 3 2n3904 BJT's. The resistor values are aprox the values in the schematic. The Diodes are 1N4003. Vcc is 5v (~4.9v) The schematic can be found here https://www.instructables.com/id/Digital-Logic-Gates-Just-Using-Transistors/ I have everything hooked up like the schematic shows. The issue I am having is that it is not working as I would expect a nand gate to work. The truth table shows that if A and B are both Low then C is High.  If A is High and B is Low then C is High. If A and B are both High then C is Low Here is what really happens.  A Low: B Low: C High A Low: B High : C High A High: B Low : C Low (but still ON just very very dim) <=Shouldn't this still be a High state? A High: B High: C Low Does any one have any ideas as to why it is behaving like this. I have rebuilt this circuit about a dozen times now making sure I have things correct. I am stumped.

Question by atrumblood   |  last reply

### Questions about making computer systems from discrete components?

Question by seanroberts   |  last reply

### Where does a calculator get a random seed from? Answered

Most, if not all, scientific and graphing calculators have a #RAND button on them, this generally generates a random number between 0 and 1 (I think). Now, as we all (might) know, a calculator is a computer, and thus thinks in logic and cannot generate a truly random number, and, as we also (might) know, any pseudo-random number generated has to come from a seed value. Some things take it from the time and date, others from the time between a user's input, I have even heard stories of a program asking a used to 'bash wildly on the keyboard like a monkey'. So my question is this: Where does my calculator get its seed value from?By the way, I cut it into paragraphs to make it more readable

Question by munchman   |  last reply

### How to build a simple computer from a cardboard box (or 2) and some marbles?

Quite a few years ago (around 36-40) I read about a simple computer, made of a cardboard box, some dividers, and using 2 groups of colored marbles; whereas the object was to tilt the box  and one marble would fall through.  Depending on which of the 2 colors came through (pretty random) a move was made in the game (a simplified version of tic-tac-to).   Wrong moves were removed and eventually the "computer" learned to win the game every time. BUT I can find no reference to this, nor the book it was in.   I don't remember the title nor author, but it was very much like the book:  "1, 2, 3...Indiniry" by Gamow (it is not this book, I have it and have read it through several times looking for it).  I have been looking for this info for about 20+ years, and decided one of the more sciencey readers amongst you all might remember  it, the book or something to give me a clue to where to find this.

Question by Goodhart   |  last reply

### Electronic knowledge wanted: Transistor/Transistor logic Answered

Hi all. I am embarking on an electronics project and I was hoping to gain some info on using transistors as logic gates in a circuit. I searched both the interwebs and instructables extensively, but all the info I could find was either outdated or was in a level of techno-babble my Noobish hardware skills could not comprehend (been programming for years; Just recently decided to dabble in hardware). To summarize: I want to know how to construct AND, OR, NOT, XOR and the like and integrate it into my circuit using primarily transistors, and maybe some capacitors. Is there something I have gotten mistaken in this premise? Is this really the proper use for a transistor? Should I use something else, is there a better method? Please note that I have little experience in non-software areas (I understand what voltage and amperage is (kinda) and what serial and parallel circuits are, and the proper configurations of positive and negative). I also do not want to use a microcontroller for this; Just me and my wires. I would be immensely thankful for some help. I apologize in advance if I have gotten anything wrong here.

Question by dungeon runner   |  last reply

### IS it Logical to use Lithium ions in noramal cars?

Just Normal cars,not electric ones..I think it may not be able to charge and discharge at the same time for Lithium family..Am i right? pls  point out some faults..that you think may occur?

Question by Nr-Think different   |  last reply

### Digital Logic Design Project Combinational Lock?

In this project you are required to design a 4 digits combination lock (not using arduino)  The project is such that it can be reconfigurable i.e. there should be an option that we can change the password of the lock at run time. Input to the system is from the hex keypad. Output of the system is ‘open’ and ‘close’ words displayed on a seven segment I used registers,flip flops, mux ,comparator  but couldn't get the desired result

### Does this circuit work in reality?

I have a project (designed in CircuitMaker2000), i wanted to see if it works in real... (track the OUTPUT routes to the 3-inptut gate)

Question by ~CableGuy   |  last reply

### Mechanical Logic Gates, got some of your own design?

ADHD version at the bottom =========================================== I've been fascinated by logic gates and how they're used for quite a while now, and then I thought, "why not mechanical logic gates?". After a few brief searches on trusty ol' Google, there aren't exactly "a lot" of sources from which to draw from. I've designed a few (rudimentary) mechanical logic components myself, such as an AND gate and an OR gate (I was gonna do a negated IMPLIES gate, but I came up with the idea during Biology class, so that's pretty much gone now). The thing with electronic logic gates is that they are standardized (kinda), which makes building logic circuits easy, because you wouldn't have to build hundreds of different designs of the same logic gate just for that circuit, alone. Maybe some of you have some logic gate designs to share? Maybe we could standardize some mechanical logic gates and someone might just make a cardboard computer out of 'em :D Just to add, I am aware of the usage of weights, balls, gears, linkages, and lever-type systems for mechanical logic. We can come up with a few for each type, I guess. (this excludes fluidics, the use of water and/or air for logical computation) Yes, I have searched instructables, but even then, not a lot of sources (though some are quite fantastic, might I add). ============================================= ADHD version: Got some ideas for mechanical logic gates? Maybe we can standardize them, somehow :D

Topic by nutsandbolts_64   |  last reply

### How do i keep the LED on the whole time with logic 1 and turn off only when sending logic 0 between arduino and RF 315?

Good evening sir. I am a college student taking electronics enginneering. i would like to ask for help if you don't mind regarding the use of arduino to control the on and off states of LED. I was hoping you can help me with my programming since the LED lights seem to be blinking only upon receiving logic 1. How do you keep it on the whole time with logic 1 and off only when it receives logic 0? Thanks!

Question by JessaY1   |  last reply

### How to build a simple CPU from 74XX Logic Chips? Answered

Hi everyone! I'm wondering what are some good resources to learn how to build a simple programmable CPU from 74XX logic chips.  I'd like to build one where I use DIP switches to program the CPU.  I don't have an EEPROM/EPROM/PROM burner, so using those are out of the question.  I've seen some CPU's already that run an internet server, but they are too complicated/expensive to build and understand.  I want to learn how a CPU can be built and the principles behind it.   I have about 150 74XX chips, including a 74LS181 ALU unit.  I also have enough capacitors and resistors for the project. Thank you!

Question by prrgg14935   |  last reply

### I need to find a way to on/off a motor automatically after about 5-7 seconds. Is it possible to do this ? help needed !

Question by rukesh   |  last reply

### How can I turn a square wave to a "logic one" or ON?

Hi, I'm looking for ways to change a square wave to a logic high state. Attached is a diagram of the circuit. It picks up on when you approach it but sends out a square wave of I think about 50 Hz due to induction from mains in the body(?). I would like to turn this frequency into a logic one or ON when the frequency (from the hand) is present and for it to turn to a logic zero or OFF when no frequency is present. My goal is to get a decent logic proximity circuit that I can use to select pins for a binary multiplexer. Attached is a diagram of the circuit which is inspired by this electrocope circuit, that I am trying to interface with other logic components. Basically Im aiming for an electrostatic proximity sensor that spits out a 1 or 0 based on some threshold sensitivity. Would be super greatful if anyone had an idea of how to do this, I really need to get this working rather soon! Best M3rtzi

Question by Mertzi   |  last reply

### how to implement fuzzy logic controller for dc motors using simulink?

I would prefer step wise instruction to implement it for a for a given transfer function

Question by ankita13   |  last reply

### I m trying to control Logic with miduino s proximity sensors but the midi input goes mad. Answered

I m trying to control Logic with miduinos proximity sensors but when i connect with my mac with the miduino, the midi input goes mad with random numbers, I connected all the unused inputs on miduino with grnd but still.... any ideas?

Question by nikaki   |  last reply

### How arduino shows output on Serial Monitor? Answered

Because inorder to display output of any microcontroller in Computer we have to Use MAX232 interface. Microcontroller uses TTL(Transistor Transistor Logic) and Computer Uses RS logic. Max 232 converts TTL into RS Logic so that the output of microcontroller will be displayed in computer. But there is no MAX232 used in arduino board. Then how Arduino is displaying output in serial monitor.

Question by Rajkumar2506   |  last reply

### Fundemental Logic Freeduino maxserial board dosen't talk to pc

Bought board v015, cable, cd and Breadboard Shield from vendor, at this years Trenton Computer Festival. The vendor also had an optional de-9 to usb converter. Fundamental Logic apparently now only deals with retailers. I did exactly what the instructions "said" to do, no response, never got the board to talk to my p.c. Thought it was a little odd that the same software could be used for rs-232 and usb?  Thanks for your help! Quando Omni Flunkus Moritati

Topic by naic98   |  last reply

### Re:a MacBook Pro 15&quot;. They say that the logic board has failed, no display at all when boot is attempted. No activity.

I checked the forums answers without finding a solution. The Domain is a shopping mall here, including one of those.

### how can i convert my laptop into a desktop?

i have a macbook pro and the logic board broke, i want to make a tower out of it and maybe substitute something for the broken logic board?

Question by felixfatts   |  last reply

### How to make Person following Robot?

I want to make a robot for my digital logic design. This robot will follow the person as person walks it follow him... i want to make it using only logic gates... do plz help me to make this robot happen.

Question by ypanhwer   |  last reply

### can i frankenstien a tower with my macbook pro that has a broken logic board?

My macbookpro's logic board (\$1400) broke and i want a working comp, can i put pieces from it into an OLD tower of mine and make it work? how so?

Question by felixfatts   |  last reply

### PS2 controller to PS / 2 mouse: PIC? Arduino? Custom Logic? Answered

I've got an old PlayStation 2 controller which has a broken button, so I was thinking of making some sort of hand-held presenter mouse with one of the thumbsticks. I presume that the thumbstick consists of two potentiometers, and I can easily wire up some microswitches from the PS2 controller or an old ball mouse I've got lying around. The problem is the communication with the PC. I'm studying A-level Electronics, so I understand the protocol, but a logic circuit would be massive unless it was on a custom chip. I've found a microchip that can handle the PS2 communication, but its inputs are for light gates, like you might find in an old ball mouse. The other thing I considered was a PIC or Arduino (which I've been wanting an excuse to play around with for ages). Anyone got any ideas?

Question by Fodaro   |  last reply

### Need more linux help!

Ok. my computer boots the install disk, fine. Asks for timezone and language. But when it gets to the partitioning, I get a hole bunch of script that says Logical error 1, Logical error 2, etc. It does this for Ubuntu, Ark Linux, and Mandriva. Help me!

Topic by gimmelotsarobots   |  last reply

### Modifying camera?

I have an old analog cartridge camera Panasonic PV-IQ203D and would like to modifie it to logical imput.Thanks:Mogho

Question by xinematik

### Controlling ws2815 from raspberry-need a little technical help

Hey guys! Im pretty new to this stuff. As part of an ambilight “project” im trying to use ws2815B with a raspberry pi3b+ I use a 12V 20A (meanwell) psu for the leds and an raspberry 5.1V 2A adapter(bought it because new rpi hated everything else!). So powering seems sufficient. 12V is stable. I already managed to get the lights working somewhat. Even video capture works “fine”, so the lights are okish and delay isnt “that bad”. However i managed to fry the gpio18 on the pi... I dont know what caused it for sure - but i found a broken 12V cable to the strip. Maybe that...or... My new rpi also keeps hanging a LOT when the leds are attached. I can still push buttons and try to restart with ctrlaltdel(which sometimes works sometimes doesnt) but completely hung(instantly loses network connection and only ctrlaltdel does anything), although colors still work on the strip as the video capture captures different image. So hyperion is running. First few leds are off or look like dead pixels. The Rest shows the right colors. Can this hanging and erratic behaviour be because of different logic levels? If so which logic level converter should i be using? Ws2815 is 12V but it works as mentioned above with 3.3v logic from rpi with some errors. If i bring it to 5v will it be enough? Or 12V logic level is needed? If logic level is not the issue, then what else? Thanks a lot for any input :)

Question by ferenc.lippai   |  last reply

### How do computer power supplies convert wall power to logic-useable power? Answered

Although I have some fair experience with electronics, it has all been battery-powered. I know that a transformer can step wall voltage down, but in doing so raises the amperage, correct? I know that the forward current limit on a 555 timer is lower than most wall-wart tranformers supply, and therefore lower than what a power supply can supply? Thanks!