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.

View More On Wikipedia.org
Recent contents Top users
  1. daniel_i_l

    Convinve me not to switch to linux

    Lately I've been haveing some trouble with the Windows Xp on my laptop so I thought about switching to Linux. I use my laptop mostly for programming, writing documents, and browsing the web. Is there any good reason for me not to use linux? I don't want to make a stupid mistake and erase my...
  2. J

    How Does Touch Switch Surface Area Affect Capacitance?

    Hi, I've taken apart a touch lamp and remodelled it with my own design. The problem is that now it only works with 50% of the people who use it. The surface area of the switch is much larger than before. Is it a case of replacing a resistor or is there some fundamental problem to having...
  3. J

    How to Cure Switch Bounce: A Guide to Reading the Key

    how to cure Switch Bounce? is it a good idea to read the key more than once?
  4. P

    Does the location of a switch affect current in a simple circuit?

    Homework Statement Homework Equations Does location of a switch affect current in a simple circuit? The Attempt at a Solution I said no because the switch can be placed anywhere throughout the current
  5. S

    Really basic what happens when the switch closed question

    Hello guys, I got a small question. It says circuit consists of three identical lamps connected to a battery with a switch as shown in the diagram. When the switch is closed what happens. I did this really quick on paint. w_w_w_.hotlinkfiles.com/files/1210467_pxtdw/untitled.JPG they are not...
  6. S

    Charging a capacitor with a switch

    If you have the positive terminal of a battery connect to a switch then to one plate of a parallel plate capacitor and the negative terminal connected to the other plate, what happens when the switch is still open? Does charge build up on the bottom plate of the capacitor only or does nothing...
  7. G

    Why does an open switch stop a circuit?

    2 capacitors are connected in parallel to a battery and a switch is connected next to the negative terminal of the battery. If the switch is left open, why does the circuit stop functioning. There is no switch next to the positive terminal, and since the electric field goes from positive to...
  8. S

    Engineering How Does Closing a Switch Affect the Voltage Across an RC Circuit?

    Homework Statement The switch has been open for a vary long time, and is then at time T=0 closed. Determine the voltage V0(t) for t>0 Homework Equations voltage from a discharging capacitor is V*e^(-t/RC) Where V is the voltage stored in the capacitor, R is the resistance and C is the...
  9. P

    Would it be stupid to switch to engineering at this point?

    I'm currently a 3rd year student majoring in physics and will probably end up with a minor in math. I'm having a major crisis tryin to decide what to do with my life. I'm currently taking upper-div mechanics, but the class is pretty boring. I'm thinking about leaving physics also because...
  10. A

    LC Circuit: Initial Conditions and Switch

    Hello guys. I have a simple question regarding an LC circuit. Imagine a voltage source V_0, a capacitor C and an inductor L, all hooked up in series. I know that the equation governing the behvior of the system is V_0=\frac{1}{C}q(t)+L\ddot{q}(t), and hence q(t)=A\cos \omega t +...
  11. M

    AC RC finding voltages before/after switch

    The problem is in bold and my logic/answers/questions are below. Please check my logic and any help with my uncertainties would be...well, helpful. thx The switch has been in position 1 for a long time. Determine the voltage drop Vc(0) and V0(0-). Since it has been a long time the capacitor...
  12. S

    Circuit which stops other switches to work asa one switch is pressed

    I have to make a circuit which works like this : I'll have some buzzers (just bulbs which glow when switch is pressed); as soon as one buzzer is pressed, others stop working till the first switch is released. I don't have an experience of making circuits, except the easiest ones made in school...
  13. H

    Mercury Tilt Switch: Availability & Alternatives

    mercury tilt switch? hi...is mercury switch available in stores and can be easily found?? also is there some circuit that functions same as the mercury switch?
  14. scupydog

    Solve the Mystery: Find the Switch that Lights the Attic

    In the cellar you have three light switches, one of which turns the light on in the attic. You can only go upstairs once to check the light in the attic. Which switch turns on the light?
  15. Math Is Hard

    U.S. switch to digital TV broadcasting

    https://www.dtv2009.gov/AboutProgram.aspx I ordered my $40 discount coupon for a converter box, since I am one of those who make do with rabbit ears.
  16. Cincinnatus

    Should I switch to Linux for my computer needs?

    So I just got a virus on my Windows XP computer. I need to format it and start over. This time I'm seriously considering running Linux, I haven't decided what distro yet. So, the question is, should I run Linux over Windows XP? About me: -I am not really an expert computer user, though...
  17. 2

    Struggling With Calc 1: Should I Stay or Switch for Calc 2?

    Ok i am currently in calc 1 and will be taking calc 2 next smester. I am doing well in calc 1 and am happy with it for the most part. Here is my problem the class i am in is a decent ways behind all the other classes. We just finshed the chain rule and the other classes have just started...
  18. Averagesupernova

    Where can I find low-profile multi-axis rocker switches or joysticks?

    Can anyone point me to a source of multi-axis rocker switches? Similar to a joystick, but a lower profile. A joystick is acceptable too, but most have too high of a profile. The handle should ideally be no higher than about 3/4 inch. I've tried the obvious sources through www.globalspec.com...
  19. E

    Using DPDT Switch for Negative Inputs and Rectifiers

    Are there any DPDT switch that can take negative input? i want to put a sinusoidal as input and use the output to go through a difference amplifier to create a rectifier. does it work the same if i put a DC offset so i only get positive sinusoidal input to DPDT, and then use the output to...
  20. T

    Motor as switch (dc transformer)

    here's an idea i just came up with, it's to run DC into the primary of a tranformer and get a constant output: place a brush motor (like the ones in model airplanes/cars) in series with the primary coil, the motor will spin(obviously) and act as a switch(as the brushes swap contacts) so there...
  21. C

    Engineering Finding IA After a Long-Closed Switch: A Homework Problem

    Homework Statement The problem is: After being closed for along time, the switch shown in figure 1 opens at t=0. Find IA for all time. Homework Equations I believe it would be i(t)=Ioe^(-t/(CReq)) or i(t)=(Q/P)+Ae^(-Pt) Q/p=Vo/r and 1/p is time constant or t/(CReq) The Attempt at...
  22. U

    Physics Advice for career switch into physics?

    Hello, So, I've done some research and read other posts (https://www.physicsforums.com/showthread.php?t=99432) about getting a physics degree without an undergrad in physics. Most of the questions and answers are focused around "is it possible" and most of the answers are focused around...
  23. M

    Molecular switch and mobius molecules.

    Not sure if this is the right place for this.The new nanotechology articles are fascinating. They said it is like a switch that is able to turn on and off without altering its shape. I was also reading that they had solved the puzzles of the mobius strip. are these discoveries related...
  24. D

    Easy Touch Switch for Servo Activation | Microcontroller Compatible

    I am looking for a very simple touch switch/sensor that I will be using to activate a small servo. The sensor will be connected to a microcontroller to accomplish some very basic processing of any input received. I've been told that a capacitance switch would do the job, but I've been unable...
  25. D

    Correct series-or-parallel-or-off switch wiring?

    Is this a correct way to wire a DPDT toggle switch so that you can run current through two identical resistance heaters either in parallel or in series (or not at all, so that you have off/half/full power)? +---------------------------+ | | |...
  26. P

    Solve Voltage Across Capacitor After Switch Opened

    Homework Statement http://javid.us/phys22/week14q28.jpg E=50.0 V, R=250 ohm, and C=0.50 microF. The switch is closed for a long time and no voltage is measured across the capacitor. Just after the switch is opened, the voltage across the capacitor is measured to be 150 V. what is the...
  27. P

    Learning Switch Statements: Add/Subtract/Multiply/Divide Equations

    I'm new to programming and learning the switch statements right now. I'm wondering if you can add/subtract/multiply/divide equations in the switch statements. Example: y = x^6/6 And if I want that in case 1, how do I calculate y assuming I already have x input beforehand?
  28. J

    Solid state switch or MOSFET: Which is the better relay replacement?

    Hi, I've been hearing people talk about using solid state switches/relays as replacements for relays on boards and I was wondering if someone could explain to me the difference between a solid state relay and something like a MOSFET or transistor. Why not just use one of those? Thanks, Jason O
  29. B

    A battery, two capacitors, and a switch

    Homework Statement If the switch is flipped from position A to position B, what's the charge on capacitor C1 and C2? Please see the attachment below Homework Equations Q=CV The Attempt at a Solution I know that the capacitor C1 gains potential difference of 200V (=...
  30. N

    Can I Create a Strong Enough Electromagnet for My Video Installation?

    I'm a photographer at the University of Houston, and upon construction of a video installation I need a device that will alternatively cover the lenses of two different projectors. The first thing that came to mind was an electromagnet that would control the raising of different arms...
  31. F

    Engineering Circuit with capacitor, current source, voltagr source and a switch

    Homework Statement the switch in the circuit is closed at t=0 for a very long time. find the current across the 2 ohm resistor before the switch is closed. find the current across the 5 ohm resistor before the switch is closed. find the current across the 2 ohm resistor RIGHT at...
  32. P

    Possible Causes of Inoperative Christmas Lights

    Homework Statement A student finds that a set of Chrismas-tree lights do not operate when the switch is turned on. What is the most likely cause of this? Homework Equations none The Attempt at a Solution There could be a hole somewhere along the circuit. There could have been a...
  33. F

    What happens when we close the switch?

    Hello, I have a physics midterm on monday and this question is on the study guide so help with this problem would be greatly appreciated. (ok, since this diagram isn't showing up properly, here is a pdf file that includes the diagram I am asking about...
  34. E

    Simple problem:Voltage of capacitors AFTER closing a switch

    Hello guys. Please look at this, it's a VERY SIMPLE problem and I've almost solved it, but sth is not right... It's a simple problem but i am confused regarding the method that I'm supposed to use to solve this kind of problems. So the problem is: V1 , V2 , V3 and V4, E1, E2 are given. They...
  35. J

    Building a Compact and Efficient Power Supply: Can ICs Provide the Solution?

    Hi there, I'd like to switch 220-250v AC (50/60Hz) to 5 or 3.3v DC as easily and in the physically smallest way possible. Can someone offer advice on this? Do there exist IC's that will just do this for me? I have experience with LSR's but a transformer is too bulky for my needs. Thanks!
  36. S

    Where Can I Find a 3-State PCB-Mountable Switch for Selectable Voltage Levels?

    I am making a solenoid driver that are powering remote operated valves through a solid state relay circuit. I would like each port to have a selectable voltage level 24, 12, or 5.5V with a 3 state switch. I cannot find a 3 state switch that does the trick, however. They all are in a SPDT...
  37. S

    Single switch for two items

    hello every one i was wondering what type of switch should i use if i wanted to use two items namely a cd drive and a cassette player motor. both of them are connected to two separate power supplies which means two positve wires and two negative wires. i want to use that type of selector switch...
  38. P

    How does Switch mode power supplies differ from diode rectification

    hey guys, the topic basically explains it...Can someone please help me out with this question...How does SMPS differ from diode rectification? Thanks jake
  39. R

    Help Needed Wiring a Low-Volt switch for 110v circuit

    Hello there, I am working on a project in which I would like to place some "rope lighting" on a mechanic's creeper and rig it so that when the head-rest is in the up position the lights turn on. Its not so much a functionality project, but more of an experiment and learning experience in...
  40. C

    Why Does Switch Size Depend on Stored Energy & Inductance?

    Why is the size of a switch determined by the stored energy that is to be interupted and by the inductance of the circuit it is connected to? thanks, Phil
  41. A

    About Using transistor BJT as a switch

    In order to use BJT as a switch, it's very popular to do as the picture. In the picture, V_B > V_E, so there's a current flow I_BE control the I_CE. In the other way, V_B > V_E generates the current I_CE, and the lamp will light on. But, I change the connection a little: I'll let the V_B...
  42. M

    Source free RL circuit confusion When this switch closes, does the current end?

    Hello everyone. I'm getting confused on what my professor did. Everything else makes sense to me but this one part. THe directions say: Aftering having been closed for a long time, the switch in the circuit is opened at t= 0. (a) find IL(t) for t>0, (b) Evaluate IL(10ms). I got both parts...
  43. E

    Topic Error after switch form AOL to Bellsouth/AOL

    "Topic!" Error after switch form AOL to Bellsouth/AOL I had AOL for a while and signed up for the offer where you get both AOL and Bellsouth DSL. Certain links (including those which are supposed to lead to an email to contact someone) bring up a dialog box which says "Topic!". Certain links...
  44. T

    Question: What do the different electrical ratings on push button switches mean?

    While searching for a replacement push button switch for a kitchen appliance, I have run across electical ratings that I do not understand. I'd appreciate any explanations anyone is willing to give. 1. 3A-125V-T - I assume this means that the switch can support a current of 3A at 125 volts...
  45. E

    Charge on Capacitors in Series After Switch Flipped

    A capacitor, a resistor, and another capacitor is connected in series. The first capacitor, C_1, has an initial charge of Q_0, and C_2 is initially uncharged. The switch is flipped at t=0, what is the charge on each capacitor as a function of time? So I thought Q_1 =...
  46. Pengwuino

    Do any physicists switch to cooking?

    Man am i tempted to start cooking now! but no no, ill stay a physics major... The one thing i really hate about cooking for some reason is that it takes so much more time to make food then it takes to actually sit down and eat it. Like I've told 3 people, "30 minutes to make, 3 minutes to eat...
  47. M

    Closing of switch in series circuit

    If an ammeter is connected to the negative terminal of a battery,so it is on the opposite end of the line from where the current leaves the battery and enters the circuit,right?So Why, in a series circuit, the meter needle jumps to it's full value instantaneously with the closing of the switch ...
  48. JasonJo

    Programs Should I Double Major in Applied Mathematics and Pure Mathematics?

    I am thinking about switching my double major from Applied Mathematics and Statistics (AMS) and Economics to AMS and Pure Mathematics with maybe a minor in economics. I want to keep my two career options open: Actuary or going to grad school However I have been hearing from some upper...
  49. A

    Transistor LED Circuit with Mobile Sound Control | DIY Guide

    Hi guys, i want to fix a circuit that will use a led and i want to use a transistor as the switch to the led. I would like the base current to be produced by a sound played throug ha mobile. A sound turning the light on and the same or other sound turning it off. No ideas how to do it.Thank you...
  50. J

    Is there a 7/8 bit switch for microcontrollers?

    i have 7 data lines coming out from a microcontroller... i need the 8th one to control where its going to, either to a 7 input on a RAM chip, or a 7 input on an LCD display. basically i think I'm looking for a 7/8 bit switch... does one exist? can anyone supply me with the name of such a...
Back
Top