What is Switch: Definition and 562 Discussions

In electrical engineering, a switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. The most common type of switch is an electromechanical device consisting of one or more sets of movable electrical contacts connected to external circuits. When a pair of contacts is touching current can pass between them, while when the contacts are separated no current can flow.
Switches are made in many different configurations; they may have multiple sets of contacts controlled by the same knob or actuator, and the contacts may operate simultaneously, sequentially, or alternately. A switch may be operated manually, for example, a light switch or a keyboard button, or may function as a sensing element to sense the position of a machine part, liquid level, pressure, or temperature, such as a thermostat. Many specialized forms exist, such as the toggle switch, rotary switch, mercury switch, push-button switch, reversing switch, relay, and circuit breaker. A common use is control of lighting, where multiple switches may be wired into one circuit to allow convenient control of light fixtures. Switches in high-powered circuits must have special construction to prevent destructive arcing when they are opened.

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  1. S

    Current through circuit when switch is open

    Homework Statement Seven equal resistors, each of resistance 2Ω are connected with a battery of 3V in a circuit shown. If i1 is the current when the switch S is open and i2 is the current when switch S is closed, find the value of i1/i2. Homework Equations 1)Equivalent resistance formula...
  2. adamaero

    Conversion gain for mixer (BJT switch)

    Homework Statement a) If this mixer is connected to a matching 50Ω resistor, what is the conversion gain? b) IIP3 (Third Order Intercept Point) is 15 dBm, what would be A1dB? c) What is P1dB?Homework Equations https://www.ece.ucsb.edu/Faculty/rodwell/Classes/ece218b/notes/Mixer1.pdf#page=9 b)...
  3. J

    Circuit with resistor, switch and capacitor

    Homework Statement We have a circuit with a battery, two resistors, a switch and a capacitor. We assume that the battery has a switch so that we can choose whether it should be a voltage source for the circuit. a) At time t = 0, we put on a voltage Vs over the battery in the circuit. What is...
  4. mbrmbrg

    Limit Switch, Servo Motor Resources

    I need a better understanding of limit swtiches and servo motors than I'm getting from Wikipedia :) Any website/textbook recommendations? (My background is physics.) TIA!
  5. N

    High-Power Switching using MOSFETs

    For a project, I need a means of switching a high-current circuit between two inductors. The purpose is, each inductor serves as an electromagnet, and they are switched every 15s or so in order for one of the two to cool before starting again. The system I've designed uses arduino as a...
  6. AZFIREBALL

    How does this 1971 directional flasher switch work?

    This is a diagram of an old 1970's directional flasher switch. Can anyone walk me thru the details of its operation? https://drive.google.com/open?id=1OI6bL3PXfDx8lmg2eiWDCVHg9rgm0gYl Thanks.
  7. K

    Electronics Temperature Sensing to Switch on/off an Induction Heater

    Hello, I'm having trouble thinking of ways that I can measure the temperature of an object that I am heating using an Induction Heater. A little background: The coil and workpiece will be submerged in liquid, and due to most thermometers being metal it won't work with the induction heater. I'm...
  8. D

    Can a reed switch use a wheatstone bridge/potential divider?

    Homework Statement Describe the principle of operation of reed switch and LDR using wheatstone bridge and potential divider arrangement I can't find any website that says a reed switch uses a wheatstone bridge or potential divider arrangement. The only find I have found it that that a magnet...
  9. marsupial

    Engineering The effect of a switch in a Laplace circuit analysis

    Homework Statement The switch in the circuit in has been closed for a long time. At the switch is opened. a) Find i0 for t>=0 (b) find v0 for t>=0 I don't understand the effect of the switch in the position it is in. It's acting as a short circuit, I think, so presumably the capacitor doesn't...
  10. S

    Electronics How to wire a knob switch for an old machine?

    Hello, I was wondering if I could get some help understanding the wiring of a knob switch (Link 1 and 2). It's on an old machine that we got and I can't find any schematic for switch. The purpose of the switch on the machine is to raise or lower a steel arm. There are actually two boxes...
  11. F

    Charge on the capacitor after changing the switch position

    Homework Statement Homework Equations V = I R Q= CV The Attempt at a Solution When the switch is connected to position a : 20-106 * I = 0 ( KVL) Vc = 0 , because the switch is connected for a long time. I = 2*10-5 A When the switch is connected to position b : Q/(4*10-6) - 106 *2*10-5 = 0...
  12. Danielle Agamon

    Electrical Equipment (Automatic Transfer Switch)

    What are the scenarios for the ATS (Automatic Transfer Switch to operate?)
  13. A

    Independence of Currents in Inductor-Switch Circuit

    In circuit like this If I closed the switch "s" Are the currents in mesh "I1" and "I2" independent of each other? if yes Why /why not? Thanks.
  14. A

    Simulation of transistor switch circuit

    Hello, I'm new to electronics and I'm reading a book currently to learn more about the topic. I'm currently on a section where I'm building circuits where I'm using a transistor as a switch. I decided to experiment with the circuit they gave me and put it in a simulation software called Proteus...
  15. Manoj Sahu

    Difference between a circuit breaker and a load break switch?

    Hi. I am working in on a Ring Main Unit of Siemens make. Today, my senior asked me the same question. As per my understanding, a circuit breaker is make or break switch. I mean, when fault occurs the circuit breaker trips, protecting the equipment connected to the line. I have no information...
  16. sam charlton

    Can a 24V 30A Dimmer Switch Handle the Starting Current of a 500W 24V Motor?

    Hello, I'm currently constructing an electric bicycle using a 500w 24v motor, 2X24v 7ah batteries (maybe 4 later on). I bought a 24v 30a dimmer switch to use as a "throttle". During the intitial test (on a table, not on the bike!) It worked absolutely fine for 2 minutes, but then began to smoke...
  17. Mzzed

    Switch mode DC transformer equations?

    I would like to know if there are any general equations (such as the AC transformer equations) that describe a switch mode DC transformer. By this i mean a constant frequency DC signal (50% duty cycle) that ranges from 0V to some max voltage on the primary coil and outputs some higher voltage on...
  18. B

    How long after the switch is closed does the voltage across

    Homework Statement Consider the circuit How long after the switch is closed does the voltage across the resistor drop to Vf = 20V. Answer in units of s. Homework Equations Tc = RC Q=Qm(1-e-t/RC) The Attempt at a Solution [/B] RC = .0003026 11 = 31(1-e-t/RC) .3548 = 1-e-t/RC 1.3548 =...
  19. Q

    Admissions Switch to Different Subfield for Physics PhD: Is it Acceptable?

    Last December I applied for physics PhD positions in the US. In my personal statements, I mentioned my research interests as well as specific faculty I'd like to work with. What happens if I receive an offer of admission from a school but decide that I'd prefer to do research in a different...
  20. E

    Other Should I Switch Careers? Career Advice for Data Science

    Hello, After finishing my PhD in EE/wireless communication from Canada, I could secure postdoc positions in the academia. But wanted to make a transition to the industry because it pays more and it is more stable. Applied to telephone companies for R&D positions, with no luck. I tried more...
  21. Richie Smash

    Explain How the Lamp in Circuit A Lights When Switch S is closed

    Homework Statement Hello Everyone, a pleasant good morning to all :) I will attach an image that shows a diagram of a circuit. The question based on this picture is as follows: ''When switch S is closed, the Lamp L, lights. Explain how this occurs.'' Homework EquationsThe Attempt at a Solution...
  22. S

    Programs Finish the ME program (BS) or switch to a BA in mathematics?

    So you I've screwed up in Mechanical engineering courses due to a combination of personal reasons and some tough professors. I have discovered that it is possible to finish a BA in mathematics in the same time frame as the Mechanical engineering BS degree, only one semester + the summer. I've...
  23. starstruck_

    Programs Should I Switch Majors? Advice for Physics Students

    Hey! I’m kinda down in the dumps right now because of school. I’m in my first year of physics and uh I’ve had a couple bad tests for some of my courses and I’m starting to worry that if I can’t even do really well right now, how will I make it through my upper years. I really don’t want to...
  24. H

    Motorcycle starter safety circuit

    I don't know if it's the same for a car but bikes uses a starter relay to set off a starter motor which cranks the engine. Bikes have a side stand for you to lean the bike against when stationary. In case the rider tries to start the bike with side stand deployed (could cause crash if forget to...
  25. H

    Why do we need a switch before a relay?

    So in high current circuits which involve say a starter motor in a car we need a starter relay since a normal switch cannot handle the high current flow. I think the reason I'm asking this question is because I don't understand what exactly makes the relay be able to handle the current unlike...
  26. E

    Why wouldn't activating the switch make a difference?

    Homework Statement What is the heat generated on closing the switch? Homework EquationsThe Attempt at a Solution [/B] On closing the switch, the potential difference across each capacitor should change which would cause it to charge and hence cause heat loss through the capacitors. But...
  27. I

    Switch cover Snap-up spring mechanism?

    Hi. I'm searching for a name of the spring mechanism that snaps-up and snaps-down this type of Switch cover https://cdn.sparkfun.com//assets/parts/6/9/9/0/11310-03a.jpg . on the left side of this red cover, you can clearly see the spring and few other things, that makes it to resist any change...
  28. B

    Math At the end of my Physics PhD, Switch to Mathematics?

    Hello! I am writing this to get some ideas for what to do with my future. This will be a long post so I should start by introducing myself… I am currently in the last year of my PhD studies and I will be starting my thesis soon (at least I hope so). My work is on classification theorems in...
  29. F

    Calculate resistance if the switch is closed 2 battery with different voltage

    Homework Statement before that, can you tell me about "current flow in this circuit" if : A. the switch is open B. the switch is closed the Question is No. 1 Calculate the resistance of R if the value of the current I in the figure is 0.50 A. ( i think it is related to no 2) no 2. Calculate...
  30. N

    AC Two-Way Switch: Setting Up & Testing in PSPICE

    Hello People! So currently I have an AC input going into a capacitor and inductor in parallel, and I want the output from the capacitor and inductor to go into a switch that flips from outputting the capacitive load's output and the inductor's load output, a little diagram is shown below...
  31. K

    Other Decided to switch from engineering to physics

    So I've decided to switch my major from engineering to physics. I finally got courage to man up and do what I want and I'm super excited. However, I currently do research in the BME department with a professor who is the top in his field. The research is more biophysics/applied physics type...
  32. A

    Why does this bulb get brighter after the switch is closed

    Homework Statement Homework Equations None The Attempt at a Solution The answer is B, bulb B will be brighter than before. My thought was that initially, the current gets split so that 2/3 I0 goes to the branch with 2 bulbs, since it has twice the resistance of the first branch, and that...
  33. T

    Does a Variable capacitance switch exist?

    Hi, I want to be able to vary the amount of capacitance in a circuit, ideally I'd like to be able to turn a knob to tap a bank of capacitors, something like the attached picture.Is there some sort of switching or device available that anyone can think of which does this? Cheers
  34. Hannemaster

    Adding a remote switch to my electric scooter

    Hi Guys, Im totally new here and I'm not even sure if this is the right forum, but I think there are a lot of people here who know all about electronics. Ok so I bought an electric scooter. It has an on/off switch but no kind of security. So if I hook it up to a pole and leave, people can still...
  35. Christopher Winig

    Courses Switch from Physics to Engineering as a Junior -- Coursework?

    The "should I switch from Physics to Engineering?" question has been beaten to death - so I’m sorry for repeating a variation of it. But, I haven't found answers regarding my specific case. I just got accepted as a transfer student to UCSB for Physics, which I’m pretty happy about.. because I...
  36. R

    Courses Want to switch to physics from engineering in undergrad

    So I'm currently in my second year doing biomedical engineering. I want to study physics in grad school, but am at an impasse. I can't do a physics minor because there is no space in my schedule, and I can only petition one physics course to fulfill my engineering electives. So I am debating...
  37. Nikhil N

    How to wire the contactor just to switch on and off

    I am first time using a contactor. I have a 3-phase contactor with me, Need to switch on and off without any load connected. It has two auxiliary terminals A1 and A2, for just to turn on how it should be connected?
  38. S

    MHB Solve Java GUI Switch Problem: Create JLabels & JTextFields

    This is actually Java! My current problem: I need my switch statement to show only the given information for each selected shape. For example when I click "circle" on the drop down menu, I want my switch to ask for the radius only while showing my compute button and answer. When I click...
  39. N

    Voltage across switch in LR circuit as switch is opened?

    1. I thought that when switch was closed, voltage at the right side of switch was 0 and long time after the switch is open, the voltage at the right side of the switch becomes 0. 2. After the switch is open ecause of the inductor, voltage at the right side of the switch is εL = induced emf So...
  40. A

    Mathematica How to use Switch with variable number of terms?

    Hi, I'd like to use Switch with an integer partition of a number. For example, if n=4, then I define the partition as: monodromyTypes = IntegerPartitions[n]; this gives: monodromyTypes={{4}, {3, 1}, {2, 2}, {2, 1, 1}, {1, 1, 1, 1}}. I'd then like to set up a Switch depending on what the...
  41. T

    Switch Mode DC-DC step-down PSU design troubleshooting

    I am working on a switch mode psu in step down configuration with the key components being: LM2592 (adj) http://www.ti.com/lit/ds/symlink/lm2592hv.pdf 530-PC-24-1000 http://www.mouser.com/ds/2/643/PC-594199.pdf GSIB-25 http://www.vishay.com/docs/88646/gsib25xx.pdf Using a slightly modified...
  42. T

    Lift a weight up with an EM switch

    Hello, My question is simple. Let's suppose you have an electromagnetic coil with a magnetic weight in the center of it. This coil is energized, and the weight is lifted up vertically. Now, my weight is 30 kgs. I want to lift it to a height of 1 meter. How do I calculate how much power is...
  43. M

    Current of RC Circuit After Switch is Opened

    Homework Statement See attached image for circuit diagram and givens. The switch has been closed for a very long time. a) What is the charge on the capacitor? b) The switch is opened at t=0 s. What current initially flows? Homework Equations V = IR Q=CV I=I0e-t/(RC) The Attempt at a Solution...
  44. spikey1973

    Switching 2 mainboards with one momentairy switch

    hey guys, to be hounoust I'm kinda ashamed to be asking this, but a simple thing is turning out far less simple then anticipated and i don't seem to be able to find the solving clue. i am in the situation that i want to switch on and off two mainboards (one pc mainboard and one soft-switch...
  45. N

    Programs Switching Fields: Should I finish the major or just switch?

    I'm a sophomore math and physics double major, and I'm losing interest in physics. I still love math (like seriously love), but I honestly don't see myself working in a physics lab or anything. A lot of the modern physics stuff really does not appeal to me at all. I currently plan on switching...
  46. T

    Maximizing Efficiency: The Role of Feedback in Boost Converter Switch Design

    I'm looking into the design of the control circuit for the mosfet. If I know the output voltage and input voltage then I can find the duty cycle required. I found this schematic that uses feedback Source https://www.maximintegrated.com/en/app-notes/index.mvp/id/2031 Why would I need feedback...
  47. J

    Engineering Find current in circuit (DC RL circuit with switch)

    Homework Statement Initially switch is at 0. At t = 0 seconds switch is put at 1. After 1 time constant switch is put at 2. Find equation for current for t > 2[/B] Homework Equations current through inductor tries to remain constant. i(t) through inductor in series RL circuit is i(t) = [...
  48. franktherabbit

    Engineering Transformation of resistors in a circuit

    Homework Statement From the circuit diagram ( http://postimg.org/image/lldnr7mf7/ ) calculate the net charge flown through the capacitor 2. Homework Equations 3. The Attempt at a Solution [/B] I actually don't need to solve the full problem as i understand how, what i have trouble with is the...
  49. R

    Can someone help me find an On1/On2/Both On/Off mini switch?

    I've been searching for one of these switches to no avail, perhaps any of you might know where i can get one? And it has to be a mini toggle switch because I am working with a very small space.
  50. T

    Electric potential just after switch is opened.

    Homework Statement [/B] https://postimg.org/image/6dbwajk91/ (Image inserted by moderator to make it visible in-post) In the circuit the switch is closed for several seconds, then opened. Make a graph with the abscissa time in milliseconds, showing the potential of point A with respect to...
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