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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Looking for MOSFET [closed]

I am looking for 2/4 line, efficient MOSFET for switching on/off (not more then 1 per second) as per uP-ESP8266 have load <=120 mA at 3-12V but leak-current should be less then 10uA. I always used ...
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How can I perform STDP (Spike Time Dependent Plasticity) using Keithley 2450? [closed]

In order to perform Spike Time Dependent Plasticity (STDP) characteristics of the perovskite-based memristor devices, I want to learn how can I program my Keithley 2450 to perform STDP of my devices. ...
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Peak switching power in MOSFET as seen in LTSpice, and reduction using snubber or gate resistor

I am exploring a tentative design to limit current for charging a VFD bus link capacitor from the AC mains. Simple analog current limiters using resistors and transistors are inefficient and ...
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What are the ways to test a switching IC like TOP266EG with a multimeter? [closed]

What are the ways to test a switching IC TOP266EG with a multimeter? I want to check it if it is damaged or not of course. Link to the datasheet. Here is the datasheet picture: Here is the appearance ...
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Multiple LEDs with reed switches for testing magnet placement

I'm adding MIDI to an old electric organ (saving the existing internals for dual operation). I will be using reed switches and magnets at every key for action. For testing magnet+reed positions I ...
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Best practice power on/off switching with small switch in power electronic

I am developing an industrial project as an amateur but I have no experience in power electronics. I want to add an on/off button to a PCB design with 12-36V operating voltage and 3A load current. The ...
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2 answers
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Load independent LED flasher DIY advice

I found a product that does something very similar to what I'm trying to DIY. The product purposefully combines a load independent digital flasher relay and electronic push-button controls. Depending ...
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2 answers
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Stopping reverse flow of current

The above circuit has two sections. Section A is a simple transistor as a switch circuit using BC547 NPN transistor which triggers a LED1 as well as section B. Section B is a NOT gate circuit using ...
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1 answer
74 views

Need a circuit for switching 200kHz 24V-36V signal [closed]

I need a suggestion for a N-P ch Mosfet configuration circuit that could switch 200kHz PWM signal at 24V-36V. Input for this circuit is PWM signal is MCU 3.3V pin. UPDATE: Load is ultrasonic ...
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Converting 3.3V logic to 5V logic with two common emitter transistors in series

I am working with digital signals. I would like to know if there is any alternative to boosting a 3.3V logic signal to 5V logic only using transistors. I am currently using two common emitter ...
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4 answers
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Maximum current in a relay

I have this datasheet for a Goodsky relay. It has 4 poles. The datasheet mentions that the contacts are rated for 5 A. Is this the rating of a single pole? Does this mean the relay can switch 20 A if ...
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STM32 Nucleo board, "crosstalk" between switch buttons

There are 3 switch buttons on a regular solderless breadboard each following this diagram: Upon pressing any of the buttons, I am getting spurious breakpoint hits inside the ISRs for the other two as ...
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1 answer
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Changing FPGA's clock frequency at runtime

Working on an application which may require to change the FPGA (Xilinx) clock frequency dynamically at runtime (between two different clock frequencies) so wanted to ask is it at all possible to do so ...
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1 answer
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Building the second version of my IoT vehicle control unit (VCU) and want to turn on the ignition using FETS instead of relays

I need to build the "Circuit" block of this schematic. The ignition works when the 48V voltage supply is shorted with the ignition cable. Relays worked fine, but I want to remove all moving ...
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2 votes
1 answer
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Problems of optimal commutation depending on number of pole

I am trying to design a three phase 4 pole motor, control with six-step. My problem appears when I draw the commutation to try to see how everything work. First, with a basic three phase 2 pole, there ...
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Switch Drive High-power MOSFET Trigger Module not working

Hi! I am trying to get 24V output at 5kHz frequency (square wave) from a microcontroller at the 5V-5kHz output. I am using High-power MOSFET Trigger Switch Drive Module. I connected 0V to DC- and 24V ...
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1 vote
1 answer
188 views

Switching losses in a power supply

Switching losses calculation in resistive load and inductive load are different. For a full-bridge DC-DC topology with a resistive load at the output, should I calculate my switching losses like I ...
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The problem with sensitivity time controlled (STC) based on pin diode

I'm using sensitivity time controlled (STC) pin diodes of PN:MPP 4201A-206 for our applications. Our operating frequency from 1300 MHz to 1400 MHz. See the schematic diagram below. As device ...
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1 answer
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How to connect dissimilar but close logic voltages between a chips logic out and a chips input enable pins

I have two chips and I would like the logic out of one chip to control the chip enable pins of another chip. I am just not sure how to do it. I have a chip with an output of 3.6v with logic on and -1....
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5 votes
3 answers
392 views

BJT: definition of "edge of saturation"

The book Sedra/Smith (Microelectronic circuits) tells in chapter 5 the following: My question: I found no statement on why the EOS is defined by the point where vc < (vb - 0.4V). Seems like other ...
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Current measurements - shunt switching

I have been designing a current measuring device, and since it requires high wide-range accuracy, I decided to use two shunt resistors of different sizes. The schematic is shown below: The design ...
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1 vote
2 answers
71 views

Chain MOSFETs to drive high voltage / high power signal from 3V3 GPIO?

I have a set of LED light strips (LEDs + resistors integrated) that I want to control with MCU GPIO outputs. The MCU outputs 3V3 signals. I have tested the IRBL8721 Power MOSFET and also the IRFZ44 (...
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3 votes
1 answer
99 views

Switching step-down voltage regulator gives lower output-current than input current

I'm currently trying to build a photovolatik cell -> DC Converter -> Battery-management-System. In the early stages of the build I was trying to use the adjustable voltage regulator alongside of ...
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1 answer
46 views

6V to 220V relay switch

I want to control the coil of a relay using 6V input to turn on a relay which will activate a 220V device. Is there a relay that works for this application?
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3.3 V switching off 3.3 V or 5 V

I'm hacking a device that uses USB 2.0 for another purpose - the USB 2.0 was for a communications card, and I'm changing it for flash USB storage. I have the device working (it uses the USB storage) ...
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1 answer
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How should I go about overriding or switching between an internal control voltage source when an external source gets connected?

For example, I'm using a potentiometer to modulate an internally generated +5v audio signal, and I'm sending the output signal down to the next part of my circuit. If I were to add an external input ...
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2 answers
62 views

Relay switching

What will happen if we switch an electro mechanical relay more than the specified frequency? Eg if we switch a relay from On and then back to OFF before it’s operate time and vice versa , how relay ...
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0 votes
1 answer
67 views

Control power through a resistive load from a DC source and achieve low current peaks

I want to control the power through a resistive load from a DC source and achieve low current peaks. The use case is 0-1000VDC and 0-15kW (not for the entire voltage range). All other parameters and ...
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1 vote
3 answers
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Escape room: How how to switch between lamps?

I’m building an escape room and have a little puzzle here… There is a lamp normally turned on when the people enter the room. When they solve a puzzle by putting a magnet in the correct place, I want ...
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16 votes
8 answers
2k views

Why does switching cause power dissipation?

I know that switching logic values causes power dissipation but I could never understand why. Is it because transistors need to be turned on each time we want to charge/pull up a node and discharge/...
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Trying to alternate power supplies seamlessly when a certain current threshold is hit?

I don't know much about electronics so asking the right questions is troublesome sorry about that. I need to swap from a 1S Li-Ion battery with cylindrical cells 3.8v to a 1S Li-ion battery with pouch ...
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1 answer
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USB 1 to 2 switch wiring

I have 1 USB hub with mouse and keyboard connected and I'd like to build a switch to be able to switch this hub between 2 PCs. I have a 3-position toggle switch with only 2 contact pairs, so I can ...
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1 vote
1 answer
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Looking for a 3 button selector set of buttons that can be panel mounted

I've implemented tactile button solutions using a PCBA and microcontroller, but I would like to find an off the shelf module that has three buttons that allows the user to select one of three inputs. ...
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-1 votes
1 answer
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How I can calculate the switching frequency of an SCR and replacing diode with SCR in boost converter? [closed]

I want to find the switching frequency of SCR. I want to use an SCR or a GTO thyristor so I can use a switching frequency up to 20 kHz, but as I am new so I am unable to find the SCR frequency from ...
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0 votes
1 answer
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How to electronically switch the output of an LED driver between two different 10W LEDs?

I have the circuit in the image below working with the PT4115 driver. I use it to light a 10W LED from a 24V DC source. The LED draws close to 1A. I can control it with a 5V PWM signal from an MCU. ...
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1 vote
0 answers
31 views

Implementing burst mode control in a continuous PWM switching scheme

I am designing an inductive adder with two modules where a low-side MOSFET operates under continuous PWM switching in each module. However, my intended application for this adder would require ...
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3 votes
5 answers
616 views

What is the functional difference between 4049 and 4069 hex inverters? (The 40106 IC's too)

For simple R/C oscillator circuits driving LED's - I would like to run 6 independent frequencies with one 4069 IC for random flashing "super computer" display with around 450 LED's in total. ...
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0 votes
2 answers
181 views

Relay burns out while switching high voltage solar pump

I have used the following arrangement for switching a solar pump: Input from 3 solar panels (40V/330W each)--> relay switch (S-KAP S90-S-DC05V, 30A 250VAC/30VDC)--> solar pump (8.4A, 30-300VDC, ...
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1 vote
3 answers
114 views

Unable to switch 5 V relay with 3.3 V input and BS170

I'm using an ESP-32 to switch an AC load. My PCB has onboard 12 V 3 A - From wall mount adapter 5 V 800 mA - From the step-down regulator 3.3 V - from ESP not being used anywhere. I'm getting 5V at ...
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0 votes
1 answer
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Non Inverting switching 24V with 3.3V signal using a mosfet

We have a reset circuit used in a peak hold amplifier. under normal conditions, a capacitor on the peak hold circuit is grounded by RST1 (see Circuit). P0-0 is fixed 24V voltage from the supply. When ...
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1 vote
0 answers
54 views

VGA video switching using TS5v522

I am trying to bring video card signal to switch to a single monitor. I was hoping to use the TS5v522c but am not having much success. Data sheet below. https://www.ti.com/lit/ds/symlink/ts5v522c.pdf#...
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1 vote
1 answer
40 views

Can I use PWM to lower the supply to an EM brake

I am working on a board that is supplied from 48v battery. the design contains multiple dc/dc converters (5v,3.3v). one the functions of this design is to control an Electromagnetic brake (24v 1A up ...
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0 votes
1 answer
56 views

Switching between battery 12 VDC and 24 VDC power

I need to have a device held up by a 12 V battery supply during brown outs but then restored back to normal running 24 VDC without any power interruption. The unit draws about 350 mA at 24 V. I cannot ...
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2 votes
2 answers
61 views

Switching a "common" circuit with another

I have an ATTiny85 that switches 4 loads based on data from a (Software) Serial connection. I need to switch a fifth load on when any of the other four loads are switched on. I have no more IO pins ...
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0 votes
2 answers
133 views

How to instantly (not gradually) switch on the flow of current across a transistor in saturation mode

I am relatively new to transistor switching and am having a hard time understanding what is going on with my transistor switch. I would like to 'switch on' my transistor only when the vin is >= 4....
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1 vote
0 answers
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Gate of Logic level MOSFET connect to Esp32 gpio

I want to use IRLR024N logic MOSFET to switch on/off a Sim800L module. This module consume 2A for 500μs and then consume only 200mA. I supply this module with 4V. This MOSFET able to switch on this ...
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3 votes
4 answers
355 views

RS-232 Crossover, and Protection against shorting two TXD lines

I'm in the process of designing a USB to RS-232 converter for communication with some existing boards, and I ran into two problems. First Question I need a way to programmatically reverse the TXD and ...
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0 votes
1 answer
81 views

Selecting MOSFET and resistors for high side enable switch

I've been working on a hobby project and recently got help from this community on input power source switching. I'm supplying my AVR based PCB with USB or LiPo battery power (with an MCP73831 based ...
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3 votes
3 answers
131 views

Tapered line for a SP4T RF switch

I need to use HMC241AQS16 brand RF SP8T switch on an FR-4 board. The RF ports of this QSOP package integrated circuit have 50 ohms impedance. But there is a problem, the leads of the chip have just 0....
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0 answers
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Voltage at the drain of P-channel part of IRF7319

Given the switch schematic: When I applied 5V to VCC and pressed SW1, I measured 4.8V on the drain of Q1B. With SW1 released, I measured 1.85V on the drain of Q1B. I read that power MOSFETs require ...
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