Electrical Engineering

Questions tagged [switches]

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

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35 views

Automatic power switching, grounds not connected

I'm currently working on a project that requires a 24V DC input. That is no problem, as I have that power supply available. However, the project should also remain working when the supply fails or ...
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2answers
82 views

NEED HELP FAST connecting three-wire wiper motor to an AA battery holder

I'm new here and I had a problem that needs urgent attention. I have a three wired wiper motor that I want to get moving. I want to use my AA battery holder but the wires didn't work when I connected ...
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58 views

Controlling mosfet with a battery-powered attiny85

I have to control a MOSFET in switch mode. However, the whole circuit including AtTiny is powered by a LiPo battery. AFAIK AtTiny's output pin voltage is somewhere between 0.8*Vdd and Vdd and I'm ...
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How to install SF6 Type SFG

Hello Everyone we want to pack and wiring the SF6 Model SFG but the company ABB sent us the unpacking package and in our area, no one can't packing and wiring it. we search a lot on google and also ...
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0answers
26 views

400a Brushed DC Motor Switching Device

So I'm building what you might call an intentionally janky electric vehicle, and need some advice. In case anyone is wondering, the vehicle in question is a Ripstik - I currently have four of these ...
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1answer
55 views

Voltage is 0.05 when switch is closed

I am new to electronics. Iam designing a simple circuit where I have to make a digital switch: Here is what I have designed in Proteus: There are 2 issues: I want it to output 5V when I close the ...
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4answers
820 views

How do I determine whether a switch can handle the power/current in a circuit?

I have a switch that has "3A 250VAC" and "5A 125VAC" printed on it, which I imagine are ratings of what the switch can handle, but my understanding that 3A at 250V would be 750W ...
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0answers
34 views

frequency of MCP3008

I built BOOST CONVERTER, I sample the output voltage with A/D and control it using RASPBERRY Pi3, I set the switching frequency of the BOOST CONVERTER 70KHz, and the frequency of the MCP3008 1.35MHz, ...
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1answer
51 views

How to calculate the needed capacitance of a start capacitor for a 12V 10A DC motor?

I want to use a 12V 15A switching power supply for a 12V 10A DC motor which has about 9A start current and 6A no load current, I also want to add a push button switch for on and off function to use it ...
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0answers
22 views

Soft power off with delay after flipping physical switch

I have a microPC (the Jetson Nano, 10 W) that cannot handle a sudden power loss. However, the casing I need to design it for only has a latching switch for powering on and off. I need to design a ...
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2answers
134 views

NPN circuit (breadboard)

What does this NPN BJT circuit represent, is it a switch or just a PN diode, and what should this plot look like when we sweep the value of Vbe, and why?
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1answer
70 views

5v analog switch for 3.3v logic ok?

I have a project where I want to interface with a keyboard matrix / scanner (this is a PCB from a consumer electronics device). There's already an implementation that uses some analog muxes for this, ...
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2answers
50 views

High side P-channel mosfet switch for BLDC driver (42V ~13A at peak)

I'm trying to design high-side switch for BLDC motor controller(42V ~13A). I understand that low-side switch is more efficient in this case, but controller schematics(bought as is) has an issue. It ...
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0answers
38 views

How to wire together DPDT and rocker switch without fear of short circuit?

I am working on desktop monitor raise -system with a 12V 3amp linear actuator (that has dual self locking mechanisms) and would like to use both dpdt switch to let it run up or down freely, and 2-pole ...
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1answer
28 views

MOC3043 on Multisim

I've been looking to simulate an optocoupler-triac driver for an AC Load in Multisim but I can't find a working model for a light emitting optocoupler specifically(the MOC-30XX family). I would really ...
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0answers
28 views

Electronic Power Selecting Switch

I have a circuit which works with a battery normally. The nominal voltage of battery is 3.7 V and I am using boost converter to make it 5 V. And I have a charging circuit of this battery too. So, my ...
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4answers
60 views

Transistor circuit design review

I have a customer requirement where we have to design a GPIO controlled switch. We are using NPN transistor, where when the GPIO is high(3.3V) transistor is enabled and it acts as closed switch, when ...
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1answer
66 views

CD4043 latch breadboard VS PCB

I am working on a circuit that contains CD4043 R/S latch. The design on the breadboard works and everything is great, as soon as the PCB was manufactured and components were soldered, an issue with ...
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0answers
32 views

How to bypass switch to start a humidifier [closed]

I have a humidifier that is turned on by a controller that would power up that humidifer by turning on the power (120 V). The humidifier is turned on by capacitive spring switch and will not ...
1
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1answer
27 views

Wiring a switch to a new power supply for a 12v lamp

I am trying to fix a sign that wouldn't light up anymore and I got confused when it came to installing the actual switch. It does work now but with the "fix" (replaced electronics of the ...
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1answer
42 views

Voltage divider on optocoupler emitter output

I am trying to control a load switch from the GPIO pins of an STM32 which outputs 3.3V. They need to be isolated using the optocoupler shown. The problem is that the isolated voltage supplied is 24V, ...
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2answers
68 views

Trying to find an electronic single-pole multiple-throw switch

I am trying to find an electronic component that does the following. The electronic component is basically a switch, that can switch to many different wires, based on a given input. This input can be ...
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1answer
37 views

SP3T slide switch positions

I'd like to use a slide switch to switch an output between one of three inputs. However, I'm having trouble understanding which pin is the pole and which pins are the throws. Here's a link to the ...
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0answers
37 views

Relay kept on by near transformer

I had a wireless powersocket for my PC peripherals until it stopped working. It just kept closed even if I turned it off and heard clicking. I opened the socket and replaced the board inside with my ...
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0answers
40 views

How i can automate a circuit using transistors instead switches?

I'm recycling the counter circuit of a microwave, for use it as a stopwatch, that turns on automatically, and start the count per seconds immediately when turns on, the circuit have two buttons "...
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0answers
18 views

Continuous duty tolerance for automotive resistors

What is the designation for resistors to be used in 12 v automotive applications? The resistor would pass 5-10 V continuous while the vehicle is switched on. The goal is to lower the standardized ...
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1answer
45 views

switch on delay not working (capacitor, transistor)

I built a switch on delay with a 2n2222 npn transistor and a capacitor. (I left out the base resistor (2k ohms) and the resistor for the led (330 ohms) in this simulation, but in real I added them ...
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1answer
42 views

Is it possible to use a PIR detector to switch something on and keep it on without a microprocessor?

When a PIR detector switches something on e.g. a 12V light, I know I could use a microprocessor to keep it on or do anything that I choose to programme. If I didn't want to use a microprocessor, how ...
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0answers
27 views

What manual switch do I need for multi power source system? [closed]

I have a 20A DC device that I am powering from two different 12V DC sources and one AC 120V source (the AC source will drive a PS in the case to supply 12V DC) depending on availability: Internal ...
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1answer
45 views

Encode and decode SPDT switch over single wire

I'm trying to devise a way to connect a device to a SPDT switch using only one wire. Specifically, I want to connect a wall switch to some kind of smart home thingy, and I only have a single switching ...
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0answers
27 views

Delayed Switching Between USB Peripherals

I have two USB sensor pads that cannot be connected simultaneously to the computer. Currently I am using a USB hub with individual on/off switches for each port. To change pads the user MUST turn off ...
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1answer
68 views

How to choose MOSFETS by using the datasheets infos?

I know all the theory behind the MOSFETs, how to calculate the Id current based on (W/L) and (Vgs-Vth) and etc. But, now that I need to project a real solution, I feel like all of this is kinda ...
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0answers
47 views

Automatic switches for a 12 V LED with two separate power sources

I am converting a Mercedes Benz Sprinter van into an RV. I have a 12 V LED dome light (actually several) that activate when a door is opened, powered by the vehicle's power system (battery/alternator) ...
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1answer
71 views

Is it possible to use ethernet communication between MCUs without using a hub or switch?

Is it possible to connect some MCUs together in a star topology, without using any hub or switch? EDIT: There will be a main MCU in the star topology and it will be receiving 2 different GPS datas (...
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1answer
70 views

sudden current dropping identifying circuit [closed]

Here is my scenario: I have a pair of electrodes in my device and it is submerged in seawater, so there is a current. Once I take it out the current drops and I want to implement a circuit to identify ...
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1answer
35 views

Switching USB plug between 2 devices

I wonder if it possible - If I were to use a 8PDT switch, to switch the 8 wires of a USB3 cable between 2 output ports from 1 input, would this be sufficient? Or are there issues I may run in to that ...
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2answers
140 views

Can I use a ULN2003A IC as many transistor switches?

I want to make home automation using Arduino. Instead of relay modules, I prepare my own relay module using relays and transistor switches, in between the Arduino and relays. I want to make many ...
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2answers
94 views

What is the correct name of this type of switch

new here so be kind. What or how do I make a toggle switch stay on as long as current is flowing through it and toggle to off once it stops. I did try all sorts of naming searches in google but came ...
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1answer
102 views

Why did this very simple external power source switch circuit fry my ESP32/Arduino board?

So all i wanted to do was to control a 12V motor through a big spare transistor i had lying around. So i thought it may work and tested the transistor, and indeed it worked as a switch, when feeding a ...
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2answers
47 views

Circuit of a potentiometer with switch

in a device I have bought there is this potentiometer with switch: It has 5 pins instead of 3 as a normal potentiometer: two of them are connected to VCC and GND, the other ones i do not know (there ...
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0answers
26 views

Switching Between PoE and Power Input of DC 8-36V

I am Planning to use PoE+ PD in my design. I have a DC power input option other than PoE which will be in range of 8-36V DC. I am planning to use one PD module with Integrated DC-DC converter which ...
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0answers
33 views

Insight on backup safety feature for linear actuator using NEMA stepper motor in commercial product?

I am of intermediate skill level with electronics and hardware. I am working on a linear actuator concept prototype with a partner that we plan to iteratively develop and eventually take to market for ...
0
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1answer
63 views

Ultra-low Power DC DPDT Switch: Does It Exist?

I'm working on a circuit for an ultra-low power microcontroller and two configurations are given for RFO HP and LP to operate in low and high power modes respectively. I tracked down an application ...
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2answers
52 views

How do SPST neon-indicator-lamp wall switches power their neon indicator?

I am building a totally overkill electronics repair bench for fun while in quarantine. Part of this bench build involves wiring up electrical distribution (i.e., a lighting feature to illuminate the ...
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0answers
19 views

120v motor with only T1, T4 2 and 8 reversable

This is on an an antique lathe. Someone tried to replace the rotten wire and never got it right. There are 4 terminals on the motor T1, T4, 2 and 8. I expect T1 and T4 will go to line but how to wire ...
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3answers
32 views

Using a Programmable Switch w/ 3.3V Logic Level to connect capacitor load with varying input

I am trying to connect the output of a Digitally Programmable Step-Up Boost Converter (TPS61045) with a capacitor through a switch. Basically when the boost converter turns on it turns on at the ...
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1answer
68 views

Turning old floor fan into floor floor study light

I have turned a cheap floor fan into a floor study lamp; i.e. 30cm of 240V 5W a/c LED (under cupboard) strip light facing down on to the desk. These LED strip lights can be easily daisy chained in ...
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1answer
77 views

What device controls whether a signal is high or low

In circuitry, there is always inputs in circuits (for example: input A and B into an AND gate), but what exactly allows these inputs to switch states? I think the best way to illustrate what I have in ...
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5answers
585 views

A kill switch for a car

I want to add a kill switch to my car for the fuel pump relay. The switch I would like to use is one which would need to be pressed/flicked on to start the car but when the car is turned off the power ...
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1answer
30 views

(2) motion sensors on the same circuit controlling the same lights are getting confused

I installed (2) Lutron OPS2H motion sensors in my hallway; the hallway is L-shaped. Originally both light switches worked in opposition to each other, so one was only off if the other was on and vice ...

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