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Questions tagged [switches]

Devices to interrupt or route a signal or power one of several ways.

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2answers
154 views

Looking for a USB/PCI controller that can replace a physical switch

I am looking for a component that I can drop into a circuit that will replace the functionality of a physical switch so that I can control it via computer, preferably via a standard interface (USB or ...
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2answers
2k views

Xbee Shield - Turning jumper settings into ON/OFF (XBEE/USB) manual switch

I have the following Xbee Shield where I need to constantly switch jumpers in order to allow Xbee communication and/or USB communication. The following is set for Xbee communication: "Xbee ...
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1answer
2k views

Silicon Controlled Switches: applications&suppliers

I came across this description of what are called "silicon controlled switches." I always look to balance n/p-channel electronics for stability, and using these silicon controlled switches seemed like ...
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2answers
9k views

How do I build a switch to automatically control my shop-vac?

I'm starting to get into woodworking and I've run across some high-end dust collectors and shop vacuums that turn on automatically a second after the tool plugged into them (such as a table saw) is ...
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1answer
791 views

How could a charger “cut out” when charging is complete? [duplicate]

Possible Duplicate: Why is it so problematic to have close to zero standby power consumption? How would you detect vampire/standby power? This article discusses why cell phone users have to ...
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1answer
397 views

Switch lamp with two serial switches

I have a lamp, with the usual built-in switch, which is powered via a wall-mounted socket. The socket is switched itself with a normal wall switch. So, both switches operate in series, the lamp lights ...
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4answers
1k views

Programmable point to point connections

I have an idea for a programmable breadboard, but I am not sure of the feasability of it. My thought is to connect each strip of a breadboard to some type of circuit that can make arbitrary ...
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2answers
5k views

How to turn an electromagnet on and off?

I need to control an electromagnet as follows: I need to switch it on/off every T seconds, where T is around 1 second. I need to be able to change that time, using something like a potentiometer. ...
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3answers
652 views

SPDT switch controllable by GPIB

I am looking for a fast SPDT switch that is controllable using GPIB (IEEE-488). The maximum voltage applied across the switch would be something like 10V (and in practice more than around 5V). I'm ...
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5answers
1k views

Would this button trigger alarm circuit work?

This is a dead easy question for most of you! But I'm relatively new to circuit design, so I'd just like to ask whether this circuit might work (at all!) Here's a picture of the circuit Basically, ...
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3answers
240 views

Switching Question

I am designing a power control panel for the room of many applicants. In the panel there are several micro switches available for the user to turn the appliances ON/OFF. At the end of the micro-switch ...
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2answers
126 views

Looking for a circuit switch operated by velocity

I'm not at all electronically minded, but am looking for a small electronic circuit switch that is operated by velocity. Many years ago, I used to have a Casio watch that had some sort of switch for ...
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3answers
3k views

Replacing a mechnical switch with a digital one

I have a circuit which allows me to manually (physically) switch between two VGA inputs (PCB push switches) to feed one VGA output (a standard commercial KVM). I want to be able to switch between the ...
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2answers
3k views

How to switch multiple signal lines with a single mechanical switch

I want to switch an FTDI interface with a single mechanical switch towards two different endpoints. The FTDI interface has six lines, four two-way digital lines, plus power and ground. My mechanical ...
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5answers
19k views

How do I make the turn off and turn on time equal in a NPN transistor?

I have a simple NPN switch, see the diagram. I feed a 100KHz square wave (TTL) to the base of this transistor and it turns on very very fast (a few nSec) but it doesn't turn off as fast, it almost ...
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5answers
10k views

Why do you need 2 resistors when hooking up a transistor as a switch

What is the point of R2 in the following diagram: I get that R1 controls the current to the Base, but what does R2 do?
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2answers
1k views

Combining digital signal (0/24 VDC) with analog signal (0-10VDC)

I need some hints how to make an interface circuit that would combine two signals into one: one is a Digital output is used to current sink (manufacturer wording) a load that is from 5V to 24V with a ...
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2answers
1k views

DIP switch replacement

I'm working on a board where I will need to mechanically enable/disable some functionality/portions of the hardware. I would like to have the functionality of a DIP switch (see below) but it feels so ...
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5answers
190 views

Faking poles on a simple switch

I'm making a simple switch box and I've done quite a bit of looking but I can't find a 4 pole single throw switch anywhere on the major component seller sites in the UK (farnell.co.uk etc.), although ...
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2answers
10k views

Purchasing a Switch - AC vs DC Current Specifications?

I'm trying to purchase several switches for a DC system with moderately low current (a few amps at 12V). When browsing for switches in parts catalogs (e.g. Mouser and Digikey) there are always ...
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2answers
211 views

Low voltage 2 channel stereo analog switch

I am looking for a ultra low voltage 2 ch stereo analog switch. I have two headphone audio sources that I need to switch between. It is very important that the chip can run of a 1.2v rechargeable cell ...
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2answers
13k views

Operation of infinite switch

Many electric stovetops are operated by an infinite switch, which pulses the current on and off for intervals determined by the dial setting. The actual control is effected via a bi-metal switch that ...
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2answers
11k views

Two way switch, original was 16 AMP, can I use a new 10 AMP?

I have a two way switch (for an outlet), and it was for 16 AMP. I went to a store and asked for a new one, and when I got home and was starting to assemble it, I noticed the new one was 10 AMP... Is ...
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2answers
740 views

Not use current limiting resistor for switching device on off using TIP122 possible?

I wanting to control MP3 player and amplifier box through PIC board. My project is doing announcement when person standing in near PIC board with proximity sensor. When proximity sensor detecting ...
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1answer
194 views

Voltage problem in printed circuit with switches

I've got a simple circuit consisting of a 74157 MUX, whose entries come from switches. These entries have also 10k pull-up resistors, so when the switches are open (default), inputs are at 5V. When ...
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3answers
2k views

Electrical locking mechanism (on timer)

I'm looking at making a very basic, automatic cat feeder for the odd occasion I'm not around at 2pm when she gets fed. I figured I'd keep things simple by having a door that is spring loaded, but held ...
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4answers
5k views

Switch 5V with back voltage protection

I'm trying to develop a design which involves switching a 5V rail. The design goals are: As low cost as possible (i.e. Can't use a fancy integrated solution) Relatively low current handling ( ...
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1answer
165 views

High current hot switch capable

I need to design a controller that can switch On and Off a line conducting high currents. the power line: it is supplied by a banks of capacitors the switch: it must close the circuit when a signal is ...
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1answer
224 views

Looking for device that help me split a n bit input bus, or n analog lines into two or more bus at output

I looking for device that help me split a n bit input bus, or n analog lines into two or more bus at output Please consideration concept diagram below. At input there is n bit input bus, or n analog ...
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4answers
1k views

Selecting 3.3v or 5v to supply EEPROM by µC output

I am looking to select the power supply voltage to an EEPROM depending on the output of a microcontroller. Basically I am building a universal EEPROM (flash) programmer, and I need to select whether ...
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2answers
1k views

What kind of resistors do I need to use in this Canon remote switch, if it is possible at all with the P2N2222A transistor I have?

I'm a total electronics n00b set out to create an intervalometer for my Canon EOS 350D camera which seemed super simple from the outset, but I got a bit blocked with creating a switch using a ...
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2answers
191 views

Connect multiple in/outputs in predefined order (beginner question)

I want to create a device for my guitar pedals which can rearrange my pedals in any given order. I have the following: At the beginning of the device I have an input for my guitar. For each pedal I ...
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4answers
3k views

How do transistors replace the electromechanical switch in an inverter circuit?

Quoting from wikipedia: "In one simple inverter circuit, DC power is connected to a transformer through the centre tap of the primary winding. A switch is rapidly switched back and forth to allow ...
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7answers
8k views

Switching op-amp gain resistances - how?

Given the following circuit: What is the component / circuit I should be using to switch the signal between each of the gain resistors? (the ⊠s in the schematic) The inputs ID0 to ID2 are TTL (...
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9answers
16k views

Switch capable of very high current?

I need to design a circuit that can turn a DC motor on and off. The motor is like a winch motor on a truck an can draw high amounts of current, in some cases up to 200Amps. The motor runs at standard ...
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2answers
3k views

Need advice on microcontroller to switch relay on/off

I am trying to connect an OMRON G2RL-2A DPST 12 VDC relay (G2RL relay datasheet) to my PICAXE 20x2 microcontroller. I also have a ULN2803A relay driver (ULN2803A datasheet). I managed to get the ...
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3answers
11k views

How to make a digitally controlled power switch?

I am new to electronics. I want to make a power switch controller by a digital pin as shown on the following figure. How to do this safely? Update: I forgot to let you know the bulb is just an ...
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3answers
11k views

how to connect relay and physical switch to control light

I am new in this kind of stuff so please excuse me for my lack of knowledge. I have successfully connected blackwidow (wifi + arduino) with a relay to control a 220V light bulb. Now, I want to embed ...
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2answers
1k views

How to choose a switch?

There seem to be about 4 major flavors of transistors, and then there are NPN/PNP versions. There are also relays, SCRs, and TRIACs. When I need an microcontroller-controlled switch, what rules of ...
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2answers
299 views

making a switch [closed]

I am working on circuit, I need to make a switch. What I want it to do is; when the circuit is at 4 volts it goes somewhere and when it is 6 volts it goes somewhere else. I think I can use a BJT but ...
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1answer
201 views

How can I prevent incoming calls to two phones?

I am looking to build a small circuit board that would allow me to prevent incoming calls from reaching a device but still allow outgoing calls to reach their destination. This is for a standard RJ11 ...
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4answers
2k views

Vacuum tube systems in apollo era space missions

I hope this is the right place to ask this. But my friend is just learning about electronics and just was given an old vacuum tube. Just because I'm curious, is there any technical information on the ...
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3answers
8k views

Control 220V AC line using MCU

I want to switch ON and OFF an incandescent bulb using MCU. Please suggest an electric switch (like relay or something) for 220V 50Hz AC line which can be used here. I would prefer something very ...
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2answers
906 views

Can Opening a Switch Cause a Short Circuit?

Is it possible to construct a simple circuit (sans transistors) that would cause a short circuit between two points when a switch is opened? My intuition says no, but I don't have any proof for such a ...
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2answers
308 views

relay switch selection

I know almost nothing about electronics, but I'd like to intercept the power going to a small speaker and use a relay switch to close a speaker connection on a completely different, but more powerful ...
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2answers
696 views

DPDT switch for on/off

Hey all, I'm fiddling with a breadboard to make some logic gates and instead of buying spst switches, I bought dpdt switches because they were the only ones that would fit in the board. :/ Can I ...
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2answers
8k views

How to make my own atx power switch?

I'm assembling a new computer from components. It's something I've done quite a few times, but now I would like to skip the case. Except for some structural integrity and LEDs, the only technical ...
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5answers
3k views

How to have arduino only turn on when enough power has been collected?

There was recently an article in the Christian Science Monitor about the launch of a cracker-size satellite. The article says that the satellite has, "power storage in capacitors, and switching ...
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2answers
218 views

CMOS Switch for -5, 10, and 5V

Is there any way to make a switch that uses a 5V input to open a -5V or 10V connection? (so i can switch between making a line -5 and 10V). Thanks in advance!
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8answers
78k views

Why does a resistor need to be on the anode of an LED?

Please be kind, I am an electronics nub. This is in reference to getting an LED to emit photons. From what I read (Getting Started in Electronics - Forrest Mims III and Make: Electronics) electrons ...