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

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Lighting in the hall: How to substitute a missing wire? [migrated]

I have a problem with the lights in my appartement. The current setup is below (and photos further down): simulate this circuit – Schematic created using CircuitLab There are two ...
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3answers
182 views

Clap Clap Switch Modifications

I wanted to make a modification to the clap clap switch with a schematic diagram below but instead of a LED lighting I want to make it turn on a small fan..
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2answers
72 views

Switching an LM317BTG on/off using a microcontroller

We're using an LM317BTG to power a 4V modem (the LM is connected to a 12V battery). The modem can produce peak currents of up to 2A during transmission bursts. Under normal operations, the modem ...
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1answer
71 views

Calculate current using compensation

simulate this circuit – Schematic created using CircuitLab Okay, first I'd like to apologize if this question seems stupid, but I'm preparing for an exam, and don't know how to solve this ...
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4answers
138 views

Computer controlled rotary switch

I have a circuit with a rotary switch (1 pole, 6 positions). Instead of turning this switch by hand, I would like to control it via a computer. Are there any components that can do this? They would ...
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3answers
50 views

Turn a load on with a pulse of power, keep on until (NO) button is pressed

I have a device that sends a pulse +12V when access is confirmed. I would like to keep a relay live until a button is pressed to close the circuit. This is used to start up a cars (acc) and allow it ...
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3answers
124 views

Using an SPST knife switch to power on/off a PC

The title is it in a nutshell I've got an antique knife switch that I'd like to use to power up (and down) an embedded PC. The PC power switch is essentially two wires, a ground and +5v (measured ...
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2answers
49 views

Best place for a switch when using an always connected power adapter

I recently bought this: http://smile.amazon.com/gp/product/B00II1MN5I and am planning on using it for under cabinet lighting in the kitchen. ...
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3answers
83 views

Determine break in long circuit

I have a circuit of switches like this. The switches are a long way from the supply and a long way from each other. ...
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158 views

How do I get a digital signal from a switch?

I want to essentially drive a relay using a switch. For eg: If the switch (AC Voltage : 220v, 50Hz) is switched on, it sends a digital signal to the relay to switch off.
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103 views

limit switches to control motor direction

I am trying to use two limit switches and two DPDT relays to control the direction of the motor. When the power is applied the motor should rotate one direction (direction for this question isn't ...
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2answers
95 views

Bidirectional solid state switch for solenoid

I'm building a circuit to control a flip dot display, which is basically a matrix of solenoids which you control with bidirectional current across the 25 columns and 7 rows of the board. The ...
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3answers
66 views

Switch between two digital signals with no microcontroller

I'd like to use an Arduino to send wirelessy (RF 433MHz, probably) two different digital signals to pilot two different relays (later they will be much more). I know probably this is something very ...
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1answer
71 views

How can I amplify cellphone's vibrator signal to switch my home electricity on or off?

I need to connect my Samsung s1 cellphone to my home's lights when I am away. I realised that I can use my cellphones' vibrator signal when I call my "Home" cellphone number. I know that the mentioned ...
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1answer
62 views

What is a 'normal' resistance level for a closed switch?

In a closed contact or a closed switch, theoretically, the resistance should be zero, but in actual measurements the resistance is very close to zero but not zero. So my question is: What is a ...
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24 views

TILT Sensors vibration test

I have to install a tilt sensor in an enviroment with a lot of vibrations. In a device installed in a truck. I want to know what is the vibration limit before we get a false read. I would work with ...
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1answer
30 views

Current Injection Via Jumper Design Help

I am currently designing a circuit that uses a 5V 2A power brick. The circuit requires a current source and I have seen good efficiency with Ohm's Law. The current is variable through a 2k ...
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2answers
88 views

Identifying open switches in a serial circuit

I have an equipment that includes a circuit made of a bunch of NO switches arranged in serial. This circuit includes a LED that turns on when all the switches are closed. When one or more switches are ...
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1answer
120 views

Why is the LED of my Illuminated rocker switch always on?

I recently purchased a rocker power switch from RadioShack (103-R13-135B-02R-EV) and it works great. However, even when the switch is off, the small red LED stays on. Is this normal? Won't this ...
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4answers
55 views

GPS Antenna Selector: How to electronically select one antenna from multiple available antennas?

I want to connect multiple GPS antennas to a single GPS module and select one of them based on some logic. Basically, I want the module to receive signals from only the selected antenna. Is there an ...
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2answers
66 views

Actuating a relay (either 5V or 12V) with 3V

I am trying to figure out how I can actuate a high amperage 12V relay with only the batteries I have on board. Basically the idea is here to have a 3.7V lithium cell, a momentary switch to actuate ...
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1answer
56 views

Solid State Relay Capacitance Bad for Audio?

Regarding MOSFET optocoupler relays like the Panasonic AQW212, am I correct in understanding that the capcitance between the terminals and ground when the switch is open ("off") is around 100pF when ...
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0answers
33 views

Bypass switch for amp

I've just successfully completed a CMOY amp and I'm pleased with the result. However, I want to be able to hear the difference between the original signal and the amplified signal, so I put a switch ...
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1answer
68 views

Toggle battery powered LEDs

I am helping to build a costume prop that has four LEDs lights on it (1 white and 3 amber). This device is worn on the wrist, so space for power is limited- a 9V battery or something that will fit in ...
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3answers
44 views

Identification of switch type casing type or housing type

I don't know what or how to identify this switch. Its dimensions are: 29.5mm by 25 by 21.5 tall. It has a lug for a screw on the side you can't see it is actuated by a pin on a separate housing ...
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1answer
50 views

Switching power between two 7-segment displays using NPN transistors

So, I am working on a small project and forgot to order PNP transistors to switch the power to two common-anode 7-segment displays. Like this, for example: All I have in hand at the moment is a ...
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1answer
37 views

Remote Wireless 4CH Switch On/Off - Data PIN Network Cable

Planning Stage I'm in the planning stages of making a wireless on/off switch that will basically cut off pin 6 on a network cable. I know little about electronics and I've attempted to learn as much ...
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1answer
46 views

Unexpected results in Multisim

I am in the process of selecting a N channel MOSFET for switching purposes and thus, tried out this simple circuit in Multisim. But it seems that the MOSFET conducts in the cut off mode and remains ...
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2answers
176 views

Power switch with slow control signal

I am trying to switch on and off a circuit that draws about 0.8 amp at 12 V. The obvious choice is to set a MOSFET. The problem is that the control signal (the one that goes on the gate of the MOSFET) ...
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1answer
63 views

Laser activated switch using a photo-transistor

I would like to make a laser activated switch using a photo-transistor or an LDR, by which I can switch off the lights in a room from a long distance. I just have to point the laser and it will detect ...
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1answer
95 views

Bidirectional AC Switch with IGBTs

I came across a "IGBT Bi-directional Switch" on the web while looking for a solution to my problem of protecting a TRIAC/SSR from a short-circuit. Since TRIAC/SSR turn-off is not in my control, I'm ...
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2answers
89 views

MOSFETs connected in series forming an H-bridge circuit for switching

I want to develop an H-bridge circuit using 2 MOSFET switches connected such that when the switch 1 is on (switch 2 off) the output voltage should be +5V and when the switch 2 on (switch 1 off) the ...
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1answer
45 views

Switch OFF-(ON)

Easy question here. I'm designing a circuit which needs a switch for the main power supply. I would like a switch that keep the power OFF normally and the power ON while holding the push switch. Is ...
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63 views

Control automotive AC switch via TPS voltage

The A/C compressor is engaged via a single wire that comes from the 'A/C' button on the dash board. I want the A/C button to disengage when the throttle is at 50%. The throttle position sensor (TPS) ...
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1answer
149 views

What is the simplest analog circuit for integer addition modular 2?

This probably is a rudimentary question. I would like to have a simple analog (switch) circuit for addition modular 2, or \$a_1+a_2+\cdots +a_n \$ (mod 2). Certainly, digital transistors can ...
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1answer
40 views

Electrical circuit for detecting and charging a battery at 12 v

I have an input source of 12 v at 6 amp. How can I use a toggle switch or a circuit that can detect if the source is active, it should let the voltage pass if present otherwise not. Also what is the ...
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2answers
44 views

Switch PCIe connections

I'm trying to implement a PCI express switch; one lane from SoC and, two for mini PCIe ports. Something like the picture below. But I'm confused with the Tx and Rx connections, the transmitter ...
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2answers
43 views

Linear actuator power supply and remote or switch

This will be my first DIY project involving electricity so I want to make sure I buy the correct components. I'm purchasing a used telescoping column (aluminum and steel, 4000n) that has two actuators ...
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1answer
79 views

Device to switch a 220VAC/40A resistive load

I need to switch a 220VAC/40A resistive load. I only need on/off switching, no phase control. I would like to avoid mechanical (moving parts) components if at all possible because of reliability ...
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3answers
106 views

Switch power supply/battery

I have a power supply of 5v DC 5Ah and a 12v 2Ah lead battery. I was thinking to make a circuit to switch battery line when power is off. I made a little schema, what i'd have to put instead of switch ...
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1answer
103 views

Push Button ON-OFF Five seconds

I have to design a power supply with the LTC1707. It have a enable input to control it. Now I have to enable an disable this switching supply with a push button. Only when I push in button during ...
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1answer
74 views

Best way to emulate network switching on PCB

I'm interested in wiring up some Raspberry Pi Compute Modules together on a custom PCB board with DDR2 SODIMM connector interfaces. ...
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2answers
161 views

What is the difference between 4-leg and 2-leg momentary tactile switch? [duplicate]

After many search, I don't know still that what is exactly the difference between 4-leg and 2-leg momentary tactile switch? 4-leg: 2-leg: Why do they use 4-leg in many cases? for example, ...
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3answers
78 views

Is there an IC with a series of 2-input switches that can have all elements switch with one signal?

I want to select either input A's 4 signals, or input B's 4 signals. So I'm more interested in using 3-pin like switch, that can short circuit from the either A or B (not open or close one input) Is ...
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3answers
65 views

How should a SPDT switch be wired for a digital input?

I want to connect a switch to a digital input on a logic board and make it so that the input goes high when the switch is pressed. I'll be using a SPDT switch: Should I connect the digital input to ...
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1answer
81 views

How to make a simple Video Switch?

I thought making this would be simple, but I've found it a lot harder than I anticipated! What I mean is that I have one screen/monitor, and two video players (all video is through RGB component, RCA ...
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2answers
157 views

Transistor as switch between similar voltages

I want to use an XBee to relay data coming from a serial device. The XBee will be sleeping most of the time; waking at regular intervals, powering on the serial device, relaying the serial signals, ...
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1answer
51 views

Electronic selector / gate

The circuit that I am looking for is supposed to work as follows: The circuit has, besides power, three inputs, and two outputs. The circuit is supposed to act like a get, and let an analog signal ...
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3answers
326 views

Is a protection diode needed for a resistive load?

In some applications a flyback diode is added parallel to the load. Is that because the switching causes reverse voltage for inductive loads? What if we have a resistive load instead? Do we still need ...
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2answers
60 views

Read Switch Status without interfering with LED

I'm a software guy trying to get my head around how to measure the status of a switch connected to a LED as shown below through a digital input of a MCU. My first try was many variations of ...