Relay Definition and 143 Threads

Hello, I'm working on a fire/burglary alarm panel and I need to add an external relay that closes a circuit whenever a fire alarm is detected (i.e. no voltage, just circuit closure). The alarm panel has one internal relay that activates for fire, and one that activates for burglary; each of...

Can someone please tell about the Dayton 2A562 Time Delay Relay. Does it wait 3 to 60 seconds before powering on, or does it wait 3 to 60 and then power off? I am looking for something that will run for 3 to 60 seconds and then shut off. thanks

i want to build a cheap relay that puts out at least 15hz at low voltage. the relay should operate with an input of 9v, and put out 9v but the output should be oscillating at at least 15hz(15 off-on, per second), and please don't tell me to build anything with circuitry or components. thank you.

Hello, I do not know what I am looking for other than a relay, but what I need is a way to have this puff switch http://www.mansionathletics.com/puff-switch-physical-education-recreation-children-special-needs-ability-switches-action-37294.html?channelid=Yahoo%20Shopping turn on a...

Homework Statement A relay switches on when the current through the coil reaches 0.0048A. In a circuit, a battery of 12V is connected in series with this relay it switches on when another resistor of 800 Ohm is connected to it. Calculate the resistance of the relay. Homework...

Hey everyone I got a problem. There is a line that provides 12VDC power in 1 second intervals (On and then Off, yes a signal light). The thing is I want to connect a relay to it but the relay must not turn off and on with the signal light. I was thinking of using a capacitor but I don't know...

Hey guys, I am using the following circuit to switch on/off another circuit. The problem is that for some reason the relay will disengage about a minute after it is switched on (although it seems to remain off indefinitely). Does anyone have any ideas for what could be causing this...

Homework Statement Ive been asked to create a roaming 7 day alarm for college. This alarm must trigger a lamp (output), after the input, which i am using to simulate an alarm, has been pressed 10 consecutive times in a 7 day period. if it is pressed less than 10 timesin a week, then any...

hi..i want to know if anyone of you can confirm of BS 142:1966 for relay coordination time is 0.4s? thx

Hey guys. I bought this relay http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=255-1899-ND It is supposed to operate at 11 mA. My question is, this thing has 8 pins, and I cannot find a diagram with what pin is what. Does anyone know what sort of configuration I would need...

Hey. I am trying to use a single quick pulse of about 2.5 mA to run a latching relay. I know that this signal needs to be amplified (probably with a transistor) but am unfamiliar on how to do this. Thanks for the help, John

I searched practically all of the nets and webs and still my questions are unanswered, so I decided to consult y'all. I have previously asked you guys about diode sizing to prevent back emf on a relay and you were very helpful. I am once again calling upon your help. I have some relays in my...

Homework Statement What is relay feedback? I have to use it to create an automatic tuner for the differential, integral, and proportional gains in a PID control. Homework Equations The Attempt at a Solution

I don't even know if this post is in the right place but I'm going to give it a shot anyways. I am supposed to draw a ladder diagram that controls L1, L2, and L3. L1 is supposed to come on the first time the start button is pushed. The second time the start button is pushed, L1 and L2 are...

I am trying to use some 6 volt phototransistor sensors as inputs to a plc. Can someone tell me how come the relay will not energize when the phototransistor is conducting? Thank You

I am currently looking at a Tyco Electronics Multimode Relay MT. (Schrack division). I am wondering what it means in the description when it mentions CO contact configuration.

What is a Delay-On-Dropout-Timer relay. Is this what can be used for a glow plug timer?

Okay, admittedly I am not that well versed in electronics. I can solder and follow directions well enough to put together some interesting hacks occasionally, but I'm really a greenie when it comes to certain aspects. I'm trying to find a reasonable way to accomplish turning on and off a...

I want to use 24v to break 120v loads. I understand the logic for dc circuits but I am not sure how to break 120v loads. What relay do i use? I was looking at the altronix RAC120 or RAC24. Do I break just the hot leg of the 120v? Any help on such a beginner question would be...

i have just purchased a digital lock that works on 12v dc... the lock has a transformer and a rectifier , hence i connect it directly to the mains... when i switch the button on, the lock opens... now i want to connect a keypad to this digital lock such that it opens only when a correct...

Im not sure if this should go here, but. . . Im building a motion detector. I have the breadboard hooked up the following way using an op amp, a potentiometer, photocells, resistor and led. http://img6.imageshack.us/i/breadboard.jpg/ So it seems to work fine, but I wanted to...

Hello, I want to make simple USB driven relay but I am wondering if it can be done without having a USB device on the other end. Most solutions I have seen thus far have a microcontroller that drives a relay. I was wondering if I could use a library like libusb to send data directly to the...

What is the difference between a solid state relay and a semiconductor contactor? Can both switch ac loads? This a link to a company that distinguishes between the two. http://library.abb.com/global/scot/scot209.nsf/veritydisplay/da7ec357f6a7461cc12573ad004e1e83/$File/2CDC110004C0205_07.pdf

when my pc shuts off, i want to shut off a bunch of other things too-speakers, light, monitor. to do this i need a relay but am a little perplexed on the correct wiring. (Please ignore the periods. they are necessary to make this drawing look right but have no meaning) Voltage_____| . ...

what is Rated insulation voltage for relay? On the catalogue of a relay, it says "Rated insulation voltage (Ui) V 250 (IEC), 300 (UL, CSA)" it doesn't say its AC or DC. it also says "Dielectric strength (rms voltage) Between coil and contact a V 2500 Between poles a V 2500...

I am studying EM wave and transmission lines. I see both derive equations for propagation constant \gamma: Plane wave velocity is 1/\sqrt{\mu\epsilon} and \eta = \sqrt{\mu/\epsilon} Transmission line velocity is 1/\sqrt{LC} and Z0=\sqrt{L/C}. From that the book just to say the velocity...

Can you tell me what is wrong with my timer. I want it to make a relay open and shut periodically. For some reason it's not working.

Hi, I'm switching an inductive load. Let's say a DC motor (20 A continuous current, 40 A peak surge) is going full on in one direction. I want to shut it off. Its power circuit is switched by the contacts of a very large electromechanical relay. Two questions: 1. First of all, I want to...

Hello All, I have been trying to think of a way to make a Single-pole double-throw solid-state relay circuit out of some MOSFETs that I have laying around. I determied that I wanted to this SSR to be bidirectional so that it will behave as much like a mechanical relay as possible. I first...

solved..

A 20 KV switchgear have equipped with one zig-zag earthing transformer. As you know, A grounding transformer must handle the unbalanced load on the circuit as well as the duty during line-to-ground faults. If the circuit has a lot of unbalance load, then we must concern the continuous rating of...

Can anyone explain why what China is doing (or has done recently) in Tibet in the lead-up to the Olympics is any worse than what the US did in Grenada & Lebanon in the lead-up to the 1984 Olympics in LA? (not that I'm a great admirer of China's human-rights record) As far as I know, the...

What causes relay chattering and what can be done to prevent it?

In a bus bar protection scheme applied for a double bus high voltage substation, protection systems design group have chosen high speed trip relay with operation time equal to 4 ms and a 2.5W DC bobbin; because they want to decrease the thermal stresses on output contacts of protection relays...

Just curious about something. I work on elevators and there are countless safety circuits to prevent accidents. One example is an elevator hatch door. There are contacts that have to "make" in order for the elevator to run, to prevent the elevator from taking off with the door open. These...

Hi, I'm new to this forum, and I'll greatly appreciate your help. If I can get this electrical/computer engineering problem solved, I'll be that much closer in pursuing a career as a bio-physicist. With the help of my intor physics professor, I'm designing a juice delivery system in...

I've bashed my heads through walls trying to make this work. I have a small project that is done except this part. I want to use a relays (5 pins) as switch such that when switch switches to the other end, it gets stuck there until it is reset from an external push-button. One of the...

What is the symbol for a solid state relay? I've been using mechanical relay representations in my documentation and just writting next to it "solid state." I don't like doing this, because it implies that the relay is an inductive load, which it isn't... My thought is that it should...

Are they bipolar? I can't find it anywhere :( Thanks

I don't see the difference between a contactor and a relay. Can anybody tell me what the difference is, when to use a relay over a contactor ? What are some criterias that need to be taken into consideration when choosing a contactor ? Thanks, Thanks,

In a relay race, each contestant runs a distance 24.8m while carrying an egg balanced on a spoon, turns around, and comes back to the starting point. Edith runs the first distance 24.8m in a time t1=19.3s . On the return trip she is more confident and takes only t2=time 15.1s . What is her...

can anybody explain to me how relay and solanoid work in a simplest way ? I got a few sources that explain about these two things but they confused me a little bit... Thanks

If two 55 watts light is connected to a car's 12v battery, what amp rating relay should I get? 55/12 = 4.5 * 2 = 9amps? right?