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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... I based that circuit (after lots of pondering and experimentation) on the clock in this relay computer here. 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;=related Relay counter thing. Mechanical pong game - run on relays

Topic by bart245    |  last reply

HELP - Calculating base resistor value when using a transistor to control a relay

Hi, it is a very long time since I have done anything like this so bear with me.I want to make a simple circuit using a transistor to control a relay. I think a BC547 NPN transistor will do the job. I would like someone to confirm my logic or point out where I have gone wrong.The variables are given below.Vcc - 12VRc - resistance of the coil on the relay - 362 ohmsVin - 3V - to cause the transistor to saturate and then switch the relay onI will use a diode to protect the transistor when the relay switches off.I calculate Ic to be 33mA (12V/362ohms).Using a gain of 400 I have calculated Ib to be 82.5 micro amps. Therefore I need Ib to be greater than 82.5 microamps to saturate the transistor. If I used a 15k ohm resistor then...If Vin = 3V, Ib = (3-0.7)/15,000 = 153 micro amps.Is my logic correct? Vin will vary between 0-10V. I assume this transistor will cope with this.I have attached an image of the way I intent to arrange everything.I hope this makes sense to someone.Thanks in advance.Ed

Topic by denzil023    |  last reply

How do you get a bi-color LED (3-pin) to accept two inputs and operate without a mechanical switch or relay? Answered

Example: computer has an "I'm on" light, and an "I'm working" light. I want the LED green whenever powered on, and amber when it is being accessed?  Should be a simple transistor solution without a logic chip, I'm thinking.

Question by pensic    |  last reply

retrofit nixie clock

I've always wanted a nixie clock but am new at electronics. I was thinking, couldn't you take a regular clock that uses a 7 digit display and convert that to run nixies? For example, if you want to display an 8 you would have AND logic gates on all the digit leads so when they all are on it activates a relay (or switch thing) that causes complete the circuit from a high voltage souce the nixie tube?

Topic by NetReaper    |  last reply

Stepper Power Help???

I trying to design a cheap & easy (not ideal) bi polar stepper driver using the following components: 1. (1) A Bi-Polar motor rated at 12V 1A. 2. (4) 10A 250V Dual Throw, Single Pole Relays. 3. (1) Arduino UNO Microcontroller. 4. (1) ATX Power Supply. I have the switching logic all correct from the UNO to the relays, and I have all of the wiring correct on the power side of the relay. The problem comes down to shorting the PSU.My thought is the following, and I hope you gurus can either confirm, or correct my thought process (pretty please, and thank you). Please see the Attached Pic for a basic schematic of what I'm doing. 12v = 1A * 12OHMS 12v * 1A = 12 Watts Does this mean that somewhere within the power loop, I need a 12 Watt 12 OHM Resistor, to eliminate shorting out the PSU? If this is true, what would be a practical solution other than using a big exposed spring, bar, etc... that would by its sheer mass resist all of this power?

Question by abstract_genius    |  last reply

Where can I get a schematic for a Chamberlain 5200 UBC garage door opener ?

I know the remote control is working as when I push the open/close button I can go on the main cct. board and see the signal on pin 14 of the LM2902. I can also trace the signal to pin 12 of the micro. The micro should do several things,  check whether the door is open or closed, apply power to the relay motor, apply power to the relay motor to open or close the door. The controller works in the manual mode ok, i.e. I can open or close the door, turn on or off the light. It is very difficult to trace the circuit board as it has a ground plane on the top of the board and SM components on the bottom side of the board. I am unsure of two things, first the signal going to the micio is about 1 Vpk-pk and not the normal logic level or 0 and 5v, but if this input to the micro is set as an analog signal then level may not be an issue. Secondly I cannot determine what output pins on the micro control the power relays as it is almost impossible to trace the cct.    Anyway any help would be greatly appreciated ... thanks in advance and take care ...Vic

Question by lazerspot    |  last reply

High voltage NOT gate Answered

I am creating a circuit and I need a not gate to run 20 3v 20mA LEDs. The only problem is that to run all of those LEDs (4 series circuits in parallel, if that will help) I am using 18 volts (2 9v batteries in a series). My circuit is compact (,think fitting inside an Altoids container) so a relay wouldn't work. So I need a high voltage way to make a not gate. I can read schematics if that will help you explain it, but I do need you to mention the ohms of the resistor. Thanks a million!

Question by GenAap    |  last reply

Powered USB hub that doesn't power from the PC if its available first ? Answered

Odd problem. I'm trying to find a USB hub that does NOT ennumerate when the external power isn't connected to the hub. All I've tried so far do their best to supply the connected items with what's available. I have devices attached that need more than 100mA, can't get it, and freak out. I've tried a standard hub, and cut the USB +5 from the PC, which stops the things ennumerating sure, but they don't ennumerate when you plug the power in ! I suppose I COULD put a signal relay in, or logic that would do it, but something off the shelf would be better. TIA gang

Question by steveastrouk    |  last reply

Do Amperage Ratings Add in Parallel or Series? Answered

I was wondering if the amperage ratings of devices, say, for instance, circuit breakers, add in parallel or series. For example, if I hooked up 5 20 Amp circuit breakers in parallel, would it take 100 amps to trigger them all? Or would it take 100 amps with them in series to trip them all? I'm not sure about this because I have used two 1 amp solid state relays in series to switch loads well above 1 amp, but it seems more logical for them to only do that if they were connected in parallel. Also, whatever the answer to my question is, does it apply to all devices? Circuit breakers, Triacs, etc? Thanks!

Question by mad magoo    |  last reply

how do you make a voltage splitter to dividea current in two so they act as if they were coming from different sources

Hello, i am building and rc tank that uses 4 relays to power 2 motors in both forwards motion and backwards, all running from 1 battery pack. however ive hit a snag in my developements in which the single battery pack was actually bypassing the relays as it connected to the terminals of the motors, therefore not allowing me to use one relay to apply +/- power the motor via the battery and useing another to apply -/+ via another. my only logical solution at the time was to remove 1 of the 3 battery packs being used (were each batpack contains 10X1.2v 3AH AA batteries), and arrange it so that 1 pack powerd the motor when going in reverse, and the other two were to power the motor going forwards, and although this means that my tank would run fine, and the subtraction of 1 pack doesnt make a difference power wise to the motors as they run at max efficiency with 2 packs, its still a real hassle to recharge them as i cant just charge em all up at once, the reverse motor battery pack may run out before the forwards, and vice versa, giving me less time to run the tank, than if they were together. so now you know my problem, what i need is a solution, how can i make a voltage splitter or current splitter or whatever, so that it can divide a current in two so that if i were to connect a positive wire from current 1, and negative wire from current 2 it would not complete a circuit, and basically act like they come from two totally different sources. this was what i was doing until i realised that when i tested the motors in either direction, it was actually going forwards each time i switched it on, after swaping the wires around when it would just run the motor if the relays werent even turned on. my tank has nothing yet on its motors shafts like gears or nothing, it was a simple mistake. so please, can anyone help me?

Question by oldmanbeefjerky    |  last reply

Can someone help me with a broken samsung plasma tv?

Pic links below. So I have a 58” Samsung Plasma Model: PN55. It is having the clicking on and off problem. Apparently a lot of these TV’s are having the same issue. After I researched into it the general issue was capacitors going bad on the power board. I removed my board and inspected it and see no problems with anything. The board from what I have been told was replaced a year or so ago but I cant confirm that. So my question is: What other things can I try / test to help narrow down the issue? Here is where I am at: I have the X and Y boards unplugged so just the Power board, main video board and main logic board are plugged in. The TV will not do anything with atleast those 3 plugged in. I am leaning to the main video board as the fault since I know it has not been replaced. And from what I understand the power may loop into the power board, then go into the main video board then back into the power board. I have messed with electronics some but would consider myself between a noob and a novice, but I am willing to try anything since I will be buying replacement boards if I cant figure it out. The relay that clicks is on the top left. The power comes in on the bottom left and then out/in to the video board on the bottom right. I didn’t know if there was a way to test the voltage or something coming back in from the video board, the plug has a pin explanation next to it. Thanks in advance for any help. Pics here: 

Question by davidwj  

IR trip wire with discreet components

I am in need of help and I am going insane with this. Question is about a simple circuit with IR sensor/tripwire part and 555 timer which would keep the alarm buzzer on for thee seconds. No fancy stuff like arduino or relay or anything like that just LEDs, resistors, transistors, 555 timer and a buzzer. I got the IR sensor part to work and the timer part to work, but when I try to combine them everything goes haywire and nothing works. I have IR photo transistor TOPS-030 as the IR sensor. I am really starting to lose my mind with this and it has been three years since I started doing this project. I got diagnosed with undefined neurological disease (probably MS-disease) which has slowed my down even more. I worked on the circuit every now and then not every night during the past three years =) I know this circuit is simple and it can be put together in a brief moment the thing that is driving me crazy is the fact that when I got something working then everything goes haywire. Doing very basic beginner instructable describing this circuit would be very helpful even to others not just me. It would also keep the knowledge of using discreet logic up in these micro controller days.

Topic by msiren    |  last reply

Is this the right way to wire an old, one capacitor washing machine motor ?

I actually have an old Brandt 556T washing machine, and I'm trying to replace the internal mechanical program with an arduino some electronics. Actually I'm trying to directly run the motor at it's both speeds, and both directions. So, the motor is a Selni V689, and I also have another motor laying around. It's a Selni V604. The two of them seems to be using the same wiring. So, for the moment I'm using the older one (the V604) to experiment. After some googling, I understood this kind of motor uses a single capacitor to select the direction of the rotor, and it enables the motor to start without help. We can  wire it without the capacitor, and spin it manually to start it, or use the capacitor to start it properly. So, I ended up with the schema linked here. It seems to be working, except for the old V604 which, in second speed, runs faster in one direction that the other... But for the V689, it seems to be okay. I need to ensure that my wiring schema is really ok, then I'll try to use as few relays as possible to be able to fully control this motor with 3.3/5V logic. If anyone can help me confirm that, I'll really appreciate it ! Thank you guys ! NB: I firstly thought there was a problem with the power consumpsion of those motors, but I was wrong, it's fine.

Question by etienne51    |  last reply

Homica - The remote-controlled 'smart house' using Arduino, iPhone and Apple Watch

Homica is a project that thanks to a smart web platform allows to control in a remote way (using an iPhone and Apple Watch) sensors and actuators installed on the Arduino boards. Homica not only allows to monitor our home in all its aspects through a multitude of sensors but also to perform actions on the whole installed actuators. Moreover, Homica is able to execute actions as results of events. This logic will be called "Homica Profile". Below there are just few examples of "Homica Profiles" that can be created using Homica. If we are not at home and we want that the acustic alarm is activated and all the lights goes on and an email is sent when a motion sensor detect the presence of someone in the house. If our garden has an humidity below a certain value, then we have to water it until the soil humidity will be a specific value. If we want to be notified by email if there is a gas leak. If we want that a number of lights goes on if we clap our hands once and we want to turn them off if we claps twice. If we want that all the lights or some goes on or off with a simple action. If we want that some lights goes on if a motion sensor detects a motion. If we want that some lights goes on when night comes and off when becomes day. If we want that an electric kettle and some lights goes on at a specific hour The most interesting aspect is that we can create all the profiles we need directly using the iPhone application called "Homica Remote" without any Hardware changes.   Complete Project Video Remote controlled by an Apple Watch Video Remote controlled by voice (Speech Recognizer)

Topic by MicheleC5    |  last reply

Looking for someone to write the code required for my Arduino project?

I do some volunteer work at a remote hospital in Zimbabwe and travel there every couple of years from Canada with a group to do some project work. A couple of years ago we did a lot of work on replacing their water supply infrastructure. Basically they have two pumps from a water source that feeds 5 large holding tanks which are elevated. The various houses and buildings on the site are then gravity fed from these tanks. Right now, they manually control when the pumps run and what tanks they fill with manual gate valves. When they see a tank over flowing, they either shut down the pumps and/or redirect flow to other tanks. Tanks often empty completly before pumps are turned on again, and water is often wasted while over flowing a particular tank. I have a system designed using electrical actuated valves and float switches where the pumps will start automatically when the level drops below 1/2 full in a particular tank and will automatically redirect the pumps to the next tank once full and will shut down the pumps when all tanks are filled. My expertise is in "old school" relay logic, so I would like to use an Arduino Mega 2560 as the brains of the system to control the supply of water and display tank levels, pump status and valve status at a single location. I have no problem designing the system, controlling pumps and valves, my problem is my lack of experience with Aruino programming. I'm looking for a "volunteer" to develop the sketch....... I can provide all the schematics and sequences for the design including all wiring back to the Arduino, again, it's the sketch I need! It's a tall order, but maybe someone would enjoy the challenge!

Question by 01221    |  last reply

What do I need to start getting into electronics?

I saw an instructable on here for an 8x8x8 LED cube, and was completely inspired. When I was younger (I'm 19) I built a few things out of those snap-together electronics kits, but nothing involving a soldering iron or a breadboard. I've bought myself a breadboard and a few little pieces to try to start out, but I know I need more--and I'm not totally sure what. On my list is a soldering iron (I have one but it's a piece of junk), red/black wire, a multimeter, and an assortment of resistors, and an arduino, but past that I still feel like I'm missing something vital. My current project list is: A 4x4x4 LED cube (just so I can know the fundamentals before jumping into an 8x8x8) A stereo (I have 2 car speakers that are just laying around, I'm hoping to turn them into something useful) Touching up my benchtop power supply (I built one out of a computer PSU but it looks.... not good) A high-power LED flashlight (my mom is into photography and saw a post about using an LED for an improv light source--the pictures turned out great, so I want to build one that has enough brightness to be used in a real photoshoot) An LED visualizer (This is one of the more daunting ideas I've had, I realize programming will be a bit difficult... I was hoping to use RGB LEDs and a microcontroller to handle the logic) I have a bit of experience in coding, nothing too impressive, but enough where I feel that I can grasp at least the programming of an Arduino (which so far looks user friendly and relatively simple [to me]), and on top of that I've been into computers and done a bit of tinkering with electronics before and so I know the basics of resistors (and LEDs together), capacitors, relays etc. Any advice would be greatly appreciated :)

Question by ninjatails    |  last reply


This is similar to my other topic, but I think it's worth a new topicmy company will be called electroni-C (pronounced electroni-see)I came up with cool marketing groups and product names, such as:electroni-CHIPSflavors: original (a bunch of generic boards that makes breadboarding easier, such as a 555 board, potentiometers that actually work with bread boards, a couple of mini powersupplies, jumpers, breadboard to aligator adapters, etcspicy: A lot of power stuff, like powersupplies, not just for breadboards, but for real finished projects, such as a circuit similar to mintyboost (but not the same, it'll be like a DIP package)optical (better name needs to be thought of) various LEDs, led drivers, optical sensors, and some logic to make everything useful. LED displays with integrated resistors for 5 volt (useful for less solder joints and less mess on a breadboard.caffine: motors, H-bridges, relays w/ saftey diode, servos, etc.Electroni-COOKIESNames are TBD, but here's what they are. They are called cookies because they are bigger and come in a box (oppose to a bag like electron-CHIPSdecade resistor control boxdecade capacitor control boxdecade inductor boxa big power supplyelectroni-CUSTOMIZEcustom PCB and plexi etchingelectroni-CASEcustom enclosures (basically a generic enclosure that has holes and squares cut out specifically where you want them)electroni-KITS (better name that begins with C needs to be found)H-bridge12volt regulated powersupply9volt regulated powersupply5volt regulated powersupply3.3volt regulated powersupplyR/C equipmentpulsing music LEDsthe resonator (just you wait!)lucid dream machinethe diode calculator (using thousands of diodes and switches for input, you can make a calculator, plus some resistors for the LED display)I will also carry some basic components such as resistors, LEDs, capacitors, etc..suggestions are appreciated!EDIT: website is in development.. uhhh.. by mehere's the site, all pictures were done by meI would like my own URL, but eh, wacha gunna do for free

Topic by guyfrom7up    |  last reply

(Arduino) automated macro-photography rail

Hi everyone, I would like to build an Arduino automated macro-photography rail (let's call it AAMR). I'm a decent software engineer and I want to learn electronics, so I'm looking for someone telling me I'm going in the right direction... The idea sounds simple, I want to : 1/ place the subject on the AAMR 2/ input the # of pictures needed to perform a "focus stacking" ( 3/ push the start button and make the AAMR loop n times through the following steps : - trigger the camera to take a picture of the subject - move the subject 1 millimetre toward the camera After a couple weeks reading and day-dreaming, here are my thoughts. I need : - to read more :) - a steeper motor and its driver (I own bipolar steppers and L298 / L293 IC) - to trigger the camera (Canon EOS 70d : remote cable is quite easy to make) - a potentiometer and 2* 7segment displays (input and display the # of pictures) - a start button - a reset button to make the rail come back at position Zero - two "end of course" buttons (not sure about the English terminology), just in case the motor wants to jump over the board - power (5v for the arduino and the logic, 12v for the motors) I. Arduino ---------- First things first, I plan to use an Arduino Uno during prototyping and replace it by a home made board in the final product. Uno has 14 Digital I/O Pins and 6 Analog Input Pins : - stepper => 6 Digital pins (3 ?? if using - 7segment led => 3 Digital pins if using shift registers ( - start button => 1 Digital pin - reset button => 1 Digital pin - "end of course" buttons => 2 Digital pins - camera trigger => 1 Digital pin (to drive an opto isolator / solid state relay) - potentiometer => 1 Analog pin 14 Digital pins ! Uno should do the job, am I right ? (I know I could use Analog pins as Digital ones, but it seems I don't need it...) II. PSU ------- Next interrogation is about power supply : I don't want a battery powered device and my options are scarce : - ATX PSU supplies both 5 and 12v, but Arduino seems to like >5v, so ATX doesn't seem a good choice - home made PSU from an existing wall wart -> voltage divider to get ~7v and ~14v -> 7805/7812 voltage regulator (may need heatsinks and/or little fan) If I do the math : - Arduino : 50ma - Stepper motor : 700mA max - L298 : 70mA (quiescent current) - 2* 7Segment LED (multiplexed) : 2 * 80mA (estimated) - Shift registers IC (SN74HC595N) : 1ma (optional : Hex inverter 74LS04 : ?? mA) Total : around 980mA... Am I doing right ? I have tons of questions left (Hex inverter, filter capacitors, motor noise reduction, solid state relays...), but it's a good start :) Sorry for the long post, and thanks in advance for your answers ! D

Topic by djezzz    |  last reply

Supercapacitor for power supply design?

Hi I am new to electronics but I have studied the basics and the logic. I have 6 3000 farad supercapacitor from Maxwell(not the boost cap one) with a power rating of 3 watt- hour, so each capacitor holds about 10.8 kilo watts(3 watt x 3600 seconds= 10,800 watts). So I have been wanting to make a power supply out of these and two types have ran across my mind: 1. Turning them to a voltage multiplier type of circuit( so like a voltage multiplier but the capacitor is these capacitors). So I would have an output of 500 amperes(6 3000 farad capacitors in series would have a capacitance of 3000f/6=500f) and output voltage of 16.2 volts. For charging this power supply I will use a step down transformer connected to the mains with some circuit breaker, fuse, switch and ballast/ resistor at its input, the transformer will step it down to approximately 2 volts ac which then I will rectify with a bridge rectifier. 2. Putting them in parallel so I would have a total capacitance of 18,000 farad at 2.7 volts, and putting them in parallel with my power supply. So this works by charging the bank and the bank will discharge when fully charged. The power supply will be the same like the first design power supply. However this circuit seems very risky and I might need some feedbacks. For your information I live in Indonesia and the wall outlet have 220 volts with amperage of ~20 amperes So I have some questions which are: Q1. Which power supply design is more ideal in terms of safety and efficiency? And how can I improve? Q2. For power supply design 2, I believe I might need some "system" for timing the charge and discharge of the bank,what circuit or system should I use/ make? How about using relay? Or spark gap? Q3. What should I do to avoid explosion of capacitor in both power supply Q4. What components are recommended for the charging power supply and what diodes are recommended for the design one capacitor bank? I already have the thick wires necessary for this since i know both systems deliver huge amount of power. And please inform me if there is any mistake or anything wrong. Any input is very greatly appreciated, you don't meed to answer all question since i know is a lot and i don't want to waste anyone's precious time. Thank you so much for your time.

Question by dikap123    |  last reply