Questions tagged [switching]

Switching can be defined as the change in state whether it be an analog, digital, or mechanical device. For digital devices, switching can be defined as a transition from HIGH to LOW or vice versa. For analog devices, switching can be defined as a change of operation within a transistor. Mechanical device examples include physical light switches or button switches. Ultimately, switching interrupts current from going into another conductor path.

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1answer
51 views

Relay controller without the relays? [closed]

I need a way to turn off/on about 20 relays or FETs using RS-232 codes. (I do not want to program a generic microcontroller, I want a dedicated device that is designed to do switching only.) I notice ...
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5answers
65 views

Control a large number of switches with RS232 via discrete logic

I am working on a device that requires controlling a large number of switches by RS-232. The designer wants to use a microcontroller. So in that scenario, a code is sent via RS-232 to the ...
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52 views

Transistor switching

I have 1 ~ 3 V signal which turns on the LED. I want that signal to act as a switch to drive a relay. I have 12 V power supply in the circuit which could be used to power relay coil. I want to use a ...
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4answers
83 views

How to “lock” an input based on another input

I'm trying to control a lot of devices using a microcontroller, and I need to control them faster than a shift register can move data. So, I want to make 'groups' of devices that I can switch between, ...
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32 views

What do you call an electronic switch that maps from some configurable subset of inputs to one output?

Analog multiplexers are N x 1; they select one input from a set of inputs and route it to one output. Analog crosspoint switches are N x M; they select various subsets of inputs and route them to one ...
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187 views

Why is this H-Bridge circuit not giving me a switching output

I have been trying to design this H-bridge circuit as a little project. I cannot seem to get the output I want and I am not sure why. At the output I am getting a constant voltage line instead of a ...
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2answers
41 views

How to reduce the DC power supply ripple noise during relay switching

I have relay controlled by BC547 transistor powered by 24V Zener regulator. The transistor is switched by a microcontroller which is powered by a 5V linear regulator. The linear regulator receives ...
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6answers
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Help me understand this circuit - unexpected LED behaviour

I'm well out of my depth here – please be kind! My kids and I have set up the circuit below and the LED is lighting up unexpectedly. When the switch is off, so is the motor BUT the LED is on. But when ...
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33 views

Reference ground for Vgs on the source pin of an N-channel MOSFET

Hey fellas, So I'm trying to take advantage of n-channel mosfet's inherent low RdsOn, but also want a high-side configuration. I've got the following circuit here and it seems to work in this ...
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2answers
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ULN2003/ULN2803 for Switching Application

I'm prototyping a board which will drive a control module. I'm not an electrical engineer by trade but I have tried to learn as much as I can. The board is intended to interface with 8 logic lines, ...
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4answers
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Resistor switching methods

I have an application where I need to measure the voltage drop over a resistor that varies between 10 ohm - 50 kohm. As I have this set up as a voltage divider, with the result being read by an AtoD, ...
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2answers
217 views

Turn off PNP BJT with high impedance output

I am making PCB where I need to turn off PNP BJT with my MCU. But my MCU is only 3.3V and it can't reach emitter voltage. So, it is good practice to turn it off by setting output pin to high impedance ...
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Double pulse test drain current not reaching peak

I want to have a double pulse test for the MOSFET. The drain current needs to reach 17 A peak. So to choose the capacitor and inductor I did the following, DC Bus voltage = 400 V $$L\dfrac{di}{dt} = ...
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3answers
493 views

What is to be used to switch the load: Relay or MOSFET?

I have a circuit that requires to switch on/off the load using arduino control signal. The load uses 5V DC and upto 3A current. MOSFET or relay must be used to switch the load supply on/off. Input to ...
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What are the multiplication factors for switching frequencies in 3 level NPC, TNPC and 5 level inverter topologies with 2 level Fsw as reference?

I am trying to compare losses of 2 level inverter topology with that of 3 level NPC, TNPC topologies. However, it may seem not a valid comparison if the switching frequencies of every topology remains ...
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Switching High-power MOSFET in nanosecs with 5V Logic

I want to switch upto 36V and higher onto a piezo disc. Wideth of the pulse I want to apply is 250 nano-secs.(4 MHz - piezo resonant frequency ) I summarise the problems I face here. I apply the pulse ...
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1answer
52 views

PWM level shift

I have a 10 kHz PWM (0V (LOW) to 3V3 (HIGH)) which I wish to level shift as following; when PWM is high (3V3) the output should be 0V while when PWM is low (0V) the output should be -12V. Ideally this ...
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1answer
60 views

What is the difference between the switching speed and clock speed of a chip [closed]

I learnt that the switching speed of Silicon-based devices are in the KHz range whereas that of III-V semiconductors like GaN are in the MHz range. How does this differ from the clock speed that we ...
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3answers
94 views

How To Make A Switch Close When Another Switch Close? [closed]

I want to use a rotary switch to switch between filters which I believe will give me different frequencies. But the problem is when I connect the positive feedback to the other filters too, naturally, ...
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2answers
53 views

How to tune period for MOSFET IRF3205 with gate driver optocoupler PC817?

I want to test 100W power output using coils for wireless power transfer project. I used 2 IRF3205 MOSFETs with 2 gate driver optocouplers PC817. I used Arduino for optocouplers. The problem is I don'...
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3answers
34 views

12 volt AC switching question

I have a 12 volt AC 300 watt plug in transformer used for outdoor landscape lighting. I would like to control individual lights with switches, however the transformer manufacturer insists no load side ...
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2answers
39 views

Switching time of a TRIAC

I have a BT137-600E and I want to know how long it takes to activate, the datasheet does not say anything about time rising or time falling
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3answers
81 views

What type of relay/switch device am I looking for?

I want to control a 24V primary device based on a digital signal from a secondary device. The secondary device emits a periodic pulse when I want the primary device to be ON and no periodic pulse is ...
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0answers
26 views

How to disconnect solar charge controller from battery when AC charger is plugged?

I am building a portable solar generator that I want to be able to switch between 2 charging sources. When the AC charger is plugged, it should disconnect the solar panels. Availability of components ...
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1answer
50 views

Power Factor in Switched Circuits

Suppose we have a residential lighting dimmer switch circuit, where the output power across the load is controlled by the phase (alpha) of SCRs. Depending on the phase, the SCRs will essentially chop ...
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2answers
62 views

Questions about signal and logic circuit

I just learned about basic logic and logic circuit from a Discrete Math book and I have a few questions: What exactly is a signal in Engineering? From Wikipedia, a signal is defined as a time-varying ...
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1answer
51 views

Easiest way to (quietly) drive a 2W 120VAC load (piezo air pump) from MCU-controlled 3V/5V/12V?

I'm trying to drive this piezoelectric air pump that requires 1.5W and runs on 120VAC 60Hz wall power. This will be controlled by a MCU/CPU of some kind (Raspberry Pi in this instance), so the control ...
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2answers
93 views

How to switch “best” between two voltage sources (5V & 3V3) for a single output (“MUX for VCC”)?

How to switch best between two voltage sources (5V & 3V3) for a "load" (e.g. a sensor in the application field or Arduino/Raspberry Pi/etc.). The basic setup is as follows: there are two ...
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4answers
59 views

Switch negative pulse

The following image shows a switch that, when activated, feeds a load with -10 volts. I have a microcontroller and I need to switch this, what can I use instead of the key? Npn transistor already ...
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0answers
31 views

PWM charging of inductor and expected current profile

This question largely covers the question I have, however the answer is unsatisfying, making the current output a function of an otherwise undescribed 'current control loop'. I see by studying my own ...
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1answer
30 views

Is there an industrial standard switching sequence for trapezoidal BLDC motor controller?

Currently I am working on a BLDC controller for 2kW hub BLDC motor of chinese origin. It does have 63 stator slots and 56 poles. I tried almost all standard BLDC switching sequences and some other ...
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1answer
45 views

How to separate pin when I connect USB?

I'm working on BL653 project, I have an issue how to left VDD_HV pin unconnected when I'm using USB? VDD_HV pin must be unconnected because I am using OPTION 1 with USB. OPTION 1 says that both VDD ...
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1answer
56 views

Monitoring circuit for the switching voltage

I would like to monitor the switching voltage which is switching between 24V and ground at a frequency of 100kHz. If the voltage is below 21V, then generate a reset signal. The lines are the ...
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1answer
72 views

Why does my MOSFET only allow current when it is switched polarity (drain to GND)?

This circuit acts strangely. I think the MOSFET is correctly placed. However, whenever I connect it to the power supply (1V 0.1A for initial testing) it doesn't let any current through - unless I ...
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0answers
38 views

Adding PWM option to continuous wave laser driver

I've been struggling for a few weeks now trying to add a PWM option to my CW laser diode driver design which works OK. When adding a MOSFET or BJT to PWM the output, I'm getting voltage spikes and ...
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2answers
67 views

Is this LDR and TRIAC circuit advisable for real time application?

Would you suggest below circuit? Will it work for a long time? What are the advantage and disadvantages of this circuit? https://envirementalb.com/automatic-street-light-circuit/
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54 views

PWM Switching of 0-200mA Laser diode driver

My main goal is to create constant current source as laser diode driver between 0-200mA, controllable by 0-3.3V analog input from MCU, And can be modulated (ON/OFF only) by square 0/3.3V PWM signal (...
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1answer
45 views

Connecting USB shielding of two hosts and one peripheral

I'm making a simple project regarding switching USB connection between two computers. I would like to know if it is safe to connect USB shielding for pc1, pc2 and peripheral together, while keeping ...
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0answers
42 views

Switching Power Supply Crowbar

In our lab we have a large fan on an instrument which works fine on a linear power supply but on a switching power supply the supply crowbar even when it's current limit is well above the operating ...
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3answers
135 views

One transistor versus two transistors as a switch

Why does the led dim first and then switch off when I use one transistor as a switch, but directly switch off when I use two transistors as a switch? These are the two circuits:
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2answers
87 views

Problem switching boost converter using 2N2222, which turns on an RF transmitter

I am using a 2N2222 transistor to switch on and off the input supply of boost converter. The output of boost converter is powering my RF transmitter and voltage regulator which is used to provide 5V ...
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1answer
57 views

High voltage Dickson charge pump switching

I am working on a circuit based on the LT1930 (DC634A) to boost input voltage between 30 and 90V. I would like to take this boosted voltage and double it via a Dickson charge pump to the required ~...
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49 views

Switching 230V load once every second

So I build a binary clock with led's as outputs. And now it has been suggest to me, that I should make it bigger and use lightbulbs instead of led's. At first I thought I would just use relays, but ...
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0answers
23 views

Issue with H-Bridge simulation waveform

I've built a simple H-bridge circuit with LTSpice: DirSigA (blue), DirSigB (red) and Vout (green) waveforms: DirSig A and B are both pulse signals with a Vmax of 5v. I've been tinkering with the ...
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1answer
103 views

High side switch load isn't working as intended per datasheet. The output is always high at 12V

I bought a high side load switch from Mouser, and per the datasheet, I added 13kohms for R1, connected Pin 1 directly to GND. The input (ON/OFF) at Pin 5 is a 5V pulse with a frequency of 20Hz and the ...
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1answer
52 views

Automatic Audio Source Switching

I was unable to find an answer to this question, but feel free to link any additional threads I may have missed. In my car, I have an aftermarket amp, and multiple HAM and public service radios. I ...
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2answers
75 views

Switching 12V with Arduino Nano

I am trying to design a circuit to switch 12V 90mA on/off using an Arduino Nano as the trigger. Is there an optocoupler/transistor/MOSFET that can tolerate 12V at 100mA on the load side while still ...
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1answer
29 views

Can I use an RIBU1C to switch a 110v fan?

I recently set up a millivolt switched gas heater with an Ecobee3 thermostat. I used an RIBU1C relay to accomplish this (Ecobee wants to switch a 24VAC circuit, and the gas heater wants a millivolt ...
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1answer
69 views

Will replacing MOSFET with a MOSFET with lower rds(on) reduce the thermal characteristics?

I want to replace a MOSFET in a legacy product. The MOSFET is a P-channel Power MOSFET that is used for PWM switching purposes (VGS @ -12V, PWM is 20% @ 200us). The FET is switching in to a 200uH, ...
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1answer
17 views

Switched Mono jack + battery: Make circuit when plugged in

I would like to replicate the functionality inside the Ampoids guitar amp (9v battery) in which the circuit is turned on only when you plugin a male 6.3mm mono jack to it I believe that the most ...

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