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Questions tagged [switches]

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

1
vote
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 ...
5
votes
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 ...
11
votes
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 ...
1
vote
2answers
891 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 ...
5
votes
2answers
306 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 ...
1
vote
2answers
680 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 ...
4
votes
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 ...
8
votes
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 ...
1
vote
2answers
217 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!
90
votes
8answers
77k 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 ...
2
votes
2answers
2k views

Accelerometer switch to trigger LED fade

I'm planning out a very simple circuit using an LED, capacitor, switch and a battery. The Idea is that the LED is off until something "bumps into" the circuit. At this point it should light up and ...
3
votes
2answers
1k views

Driving a LED Matrix with a N-channel MOSFET (2N3819) using an AVR

I am trying to wire up a LED matrix using a FET transistor as a switch. The AVR will be connected to the gate. To turn the LEDs on I have drive the pin connected to the transistor gate low, right?
0
votes
5answers
883 views

How to switch many (15) low power (40W) lightbulbs from a microcontroller?

The power rating on the bulb is the amount of power the PSU has to deliver in order for the bulb to light up the brightest right? Hence if it's a 40w bulb I need 40watts of power for it to light up ...
0
votes
1answer
277 views

Connecting an external control to a DPDT switch

Anyone familiar with the SMD1 Stepper Motor Driver Kit ? I am trying to figure out how to connect external control to the lugs on the switch assembly (DPDT push switches). The lugs already have the ...
1
vote
4answers
1k views

How to set a digital out to 24V Vcc

I want a curcuit with 3.3V and 24V supply. The micro will use the 3.3V supply, which needs to be able to set multiple industrial 24V digital outputs. My plan was a simple op amp, but as far as I know ...
4
votes
2answers
1k views

Crosspoint switch matrix for audio frequency signal?

Modular synths have recently piqued my interest, but patch cords are hell. I have been thinking of some intelligent way to route signals - something microcontroller-driven and remembering different ...
2
votes
2answers
532 views

1 x AA sized battery box with a built in switch?

I have been looking around all the internet for such a thing, but I haven't found one. Do they exist? All I would need is a neat little plastic battery holder for 1 AA sized battery, which has a ...
1
vote
3answers
587 views

Deciphering Mux/Demux/Switch Nomenclature: AxB:C?

I'm looking through Digikey's Interface - Switches, Multiplexers, Demultiplexers section (and, thanks to W5VO, the Logic - Signal Switches, Multiplexers, Decoders section as well), and I'm having ...
3
votes
4answers
2k views

How many resistors do I need for an 8 switch DIP switch block?

I was thinking of giving each switch it's own pull-up resistor, but this seems like it would be expensive and a little bit of overkill. But using just one pull-up for the entire block seems like it ...
3
votes
1answer
1k views

Need circuit to close switch on detecting current (12V)

I have a project where I need to detect whether a 12V circuit is live or not. If it is I want to close a switch (actually close a digital IO input on an Adicon SECU16 Digital IO controller). I am ...
2
votes
3answers
2k views

Switching 120V AC with Digital Logic on Isolated Power Supply

Context: A digital phase-controlled light dimmer system. 120V AC mains I use an isolating transformer (and rectifying circuit) to generate +12V and +5V DC rails. I want to use reverse phase control (...
17
votes
6answers
5k views

Choosing Configuration Jumpers - Solder bridges, 0-ohm resistors, DIP switches, pin jumpers

I'm working on a development board, and need to let users set some configurations. It will be used by students and engineers who are trying to build circuits on a breadboard; I'm not dealing with ...
8
votes
1answer
825 views

How to implement a “rotary switch” like in audio equipment?

for my current project I'm planning to use an input "device" like this in the photo (don't know its real name): It is used in a lot of musical instruments and it is like a potentiometer that can be ...
6
votes
3answers
7k views

Why do switches and relays have lower current ratings at higher voltages?

I have a switch which reads 6A 125VAC / 3A 250VAC. I can't figure out why this would be the case. The only reason I can think of the rating is the wires and contacts are only rated to take so much ...
6
votes
4answers
9k views

how to build a low-voltage disconnect switch for DC 12.4V 70A?

How can I make a device that will make the power connected as long as the voltage of the power-supply keeps over 12.4 V (adjustable) and disconnect it if it falls below? It also must connect the ...
12
votes
3answers
7k views

How do 'hand clap' switches work?

I'd like to know how a 'hand clap' switch works. You know, the kind where you *clap-clap* and the light turns on, *clap-clap* again and the light turns off. How is the clapping sound detected? How ...
0
votes
5answers
1k views

How can I build a switching circuit that scales several 12v signals down to <5v?

Let me start off by saying that I know just enough about electronics to be dangerous (how to solder, follow a simple schematic, and check for connectivity problems and usually figure out what each ...
3
votes
1answer
240 views

Signal strength on Freetronics 100% Arduino Compatible Board

I have been using a Freetronics 100% Arduino Compatible board to run switches that trigger sound file players in MaxMSP. The only sketch and patch I could use to get the board and Max communicating ...
14
votes
7answers
38k views

Make a momentary switch control a toggle

What are the simplest, cheapest, smallest ways to make a momentary switch produce a 2-state toggling output (latching momentary switch)? In other words, the output is continuously low, and when you ...
20
votes
4answers
32k views

What is the purpose of “MOSFET driver” IC's

There are dedicated "MOSFET driver" IC's available (ICL7667, Max622/626, TD340, IXD*404). Some also control IGBTs. What is the practical purpose of these? Is it all about maximizing the switching ...
7
votes
4answers
2k views

Latching switch ideas

I'm trying to build a latching switch connected to a door and would appreciate ideas. The switch is connected to a microcontroller input pin, and I'd like it to operate as follows: When a person ...
5
votes
3answers
334 views

Choosing a switching device

I am overwhelmed with the variety of switching devices. MOSFETS/BJTS Relays(mechanical/solidstate),optoisolated solutions, etc.. I need to support 15V, 60A bursts, should be high efficiency, and ...
5
votes
1answer
1k views

Old Hall-Effect Keyswitches?

I have a keyboard from an old Silent 700 TTY that I'm trying to bring to life. The problem is that each individual keyswitch appears to be a hall effect sensor. There are no part numbers; the chip ...
9
votes
3answers
2k views

Need help operating a transistor

I have a relay operated by an NPN transistor that needs some voltage applied to the base. I'm working with an arduino and if I give it a digital port, all's well. The circuit looks like this one: ...
7
votes
6answers
3k views

How can I convert the output from a momentary switch to a pulse on push and a pulse on release?

The title pretty much says it all. I have an idea to try out involving a op-amp differentiator circuit and a diode bridge, but I am flying blind. Also I am trying to accomplish this without a micro-...