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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Switching Relay at Zero_Cross Point

I'm controlling 4 Relays(10A) with a controller. While randomly switching it without zero-cross my controller gets restart. To avoid this I'm switching relays at the zero-cross point, But my question ...
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How do I switch a PIN diode using a TTL control signal?

I'm designing a TR switch for antenna using a PIN diode. The PIN diode I'm using is UM7512 make: micro semi. I need to switch between -400v (off) to +5v (on). The switching time should be 50usec. On ...
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55 views

How to drive led with transistor?

I'm trying to make a very simple circuit to switch an led using a transistor. My supply voltage is 16v, my control signal is 3.3v from an esp8266 GPIO, and my transistor is a 2222a NPN. My led has a ...
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51 views

What capacitor should I choose for mitigating frequency issues? [closed]

I'm doing this project where I'm replacing original NiMh battery (6V pack made up of 5 units of 1.2V cells) with a modern LiPo one. I'm using a pouch style battery, which has 3.7V that is definitively ...
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1answer
68 views

How do I wire this switching power supply

https://www.ebay.co.uk/itm/124258506002 How do I wire this power supply? It doesn't seem to have any connections and in my mind, it needs two for mains voltage, 2 for 12v out.
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390 views

Why are bipolar transistors used for switching applications?

I noticed that many sites targeted at hobbyists recommend bipolar transistors (mostly NPN) to switch things on and off. Bipolar transistors definitely have their purposes especially in analog circuits,...
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41 views

Automatic switching to the changed set of TTL inputs

I have 2 sets of 4 logical inputs. All inputs are active-low 5V TTL level lines with 4k7 pull-up resistors, as they may be pulled to ground by a a user pressing a switch or flipping a transistor with ...
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23 views

Issue with n channel mosfet switching with an isolated gate drive

I am trying to make a n-channel mosfet switch a load from a high voltage (250V). I am using the n channel C2M0280120D mosfet. the circuit looks something like below: simulate this circuit – ...
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196 views

Why does a spark occur when an SMPS is connected to the load circuit?

I am using a 36VDc SMPS as a power supply. A spark is generated when I connect 36V with my load circuit. Specification: Voltage source: 36VDc Current consumption: more than 3A I want to know why a ...
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69 views

Best way to switch electronically between different voltage sources for measurement

I am trying to make a circuit that can measure voltage between three different terminals. The Voltage under measurement can range upto 0 to 1500V. As you can see in the circuit, I want to Measure the ...
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45 views

High Voltage Switching with Mosfets

I am currently working on a prototype that is going to generate a burst of pulse of high voltages (e.g. 1KV). To do this, I first made a voltage multiplier and feed the mains voltage (230Vrms) ...
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1answer
61 views

SPDT mechanical relay: do NO and NC pins short between each other as pole switches

I have a mechanical SPDT relay (Digi-Key PN 281-6348-ND, I am only using one of the two channels). I also have a sensitive circuit downstream of the relay. (Image source) While a mechanical relay is ...
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Diode capacitance vs diode speed

I have some difficulties to understand what are the fatest diodes. Schottky diode are known for being the fatest diode (at least according to my knowledge) nevertheless their diode capacitance is ...
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How to separate high voltage and low voltage side of a circuit?

I want to design an ATS for a single phase. Here, I have added two sources and also control circuits. But I need to separate the high voltage and low voltage side of the circuit. In order to do that, ...
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TRIAC driver circuit behavior when switching low current loads

I'm doing a project that involves switching different kinds of loads (edit: by that I mean loads that go from just a couple mA, up to 5A or so) using the usual TRIAC + opto-isolator combo (in my case, ...
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1answer
61 views

Why won't this chip switch?

So I have a problem with The UC382x Family of chips from TI. Here is the datasheet that I'm working off UC382x, I had some confusion already with datasheets seems there's a few floating around but TI ...
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840 views

Art of Electronics 2.5 - Transistor saturation

With reference to the image below the text says When the switch is closed, the base rises to 0.6 V (base– emitter diode is in forward conduction). The drop across the base resistor is 9.4 V, so the ...
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47 views

Filtering out Switching Noise

I'm designing a custom current limiting circuit designed for electric bikes and small electric vehicles. It's purpose is to limit battery current to "dumb" motor controllers so that you can ...
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33 views

Switching load with changing polarity

From a bespoke board I'm receiving 18vdc that I need to switch. This 18vdc will usually be +18vdc but at times can be -18vdc. The load is .35A. The polarity is being changed via a H-Bridge and ...
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bootstrap vs dual power supply in MOSFET gate driver

I want to ask if my following understanding is correct or not regarding the switching circuits of power mosfet gate drivers in H-bridge where both high and low side mosfets are N-channel. If we have ...
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5answers
85 views

Keep circuit on after momentary trigger

I want to keep my circuit on after a push button is pressed and released. Trying to do this I stumbled upon soft latch circuits, but they are too complex and I don't need the turning off feature. What ...
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49 views

Switching between power sources with microcontroller

I need a way to switch a load(a high power LED) between two different power sources(50v and 100v) using a logic signal, quickly(<500us) and repeatably. I was going to use an n-channel high side ...
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1answer
75 views

Why might an N MOSFET switch output flip with no change in gate voltage (and then stick)?

In lots of places, we use a simple N-FET switch to turn on/off 24V outputs. We use a 30V rated part and stay well under the power/current limits. We've started to see recently however a couple of ...
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Why is my IRL540 slow to turn off?

I'm trying to switch 12V with an IRL540 from a 5V micro. Right now I have it a 1k resistor between 12V and the drain, the source to ground, and the gate has a 100kHz 5V square wave on it. That's the ...
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1answer
48 views

RCD “Clamp/Snubber”

I am attempting to figure out this "RCD Snubber" as seen below: The Eval Sheet says "The resistor capacitor diode (RCD) snubber for the two synchronous rectifiers consists of R3, C29, and D4 for one ...
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2answers
318 views

Utilization of MOSFETs as switches, design methodology

Let's say I want to use an nMos FET in a low side switching circuit as follows: simulate this circuit – Schematic created using CircuitLab Datasheet for IRF530 here. Now, during my education ...
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35 views

switching a buck converter with transistor

I've got a bunch of shape memory valves (SMV) that require 1.2V @ 0.25A and I'd like to use a single buck converter and DIO signals from an Arduino to switch these shape memory valves on and off. I'...
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3answers
99 views

Capacitor does not hold charge when switching power

I'm trying to create a power source switch using a relay. This's supposedly will be used for my Raspberry Pi. So what I want to do here is : Create a backup power source with battery that will ...
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2answers
78 views

How can I trigger an AC output ON when an AC input is OFF?

I have a low power 24V AC circuit powering some motorised ball valves for switching water on and off. Several of the valves are 2-wire auto-return meaning that presence of an AC signal will open the ...
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1answer
78 views

Switch 12V loads with MCU and BDW93C darlington or IRF630N

Task is to switch 2 loads with an MCU (3.3V 10mA max) and few IRF630N, BDW93C and sample pack of S901x transistors (of switch relevant components). 12V loads, likely important context for question: ...
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29 views

Adding Parallel Diodes to a load

This question is based on my previous question - Measuring voltage drop across a diode in a switched circuit I have started a bounty on that question. At the same time, I am trying to understand why ...
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2answers
25 views

How does a “mains priority circuit work”?

Dometic makes a series of DC refrigerators and one capability is to hook the fridge up to both DC and AC and it uses a "mains priority circuit" to prefer the AC source to the DC source, if both are ...
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68 views

36x LED 5730 in series: diodes burnt when LED driver (based on BP9833A or MT7854BD) powered up

Background: I have 18W, 36 LED lamp fixture which I cannot change. Originally it has 2x parallel 18off 5730 LEDs and 300mA driver. It works for some time, but diodes starts burning. I thought that ...
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Contactor utilization category

Is a contactor of utilization category AC-1 applicable to switching a whole single-family house (of say 65A, 30kW @ 230V) on or off? Since AC-1 means "Non-inductive or slightly inductive loads, ...
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10answers
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When does a transistor act as a switch, and when as an amplifier?

I'm a beginner with electronics, anyway I'm experimenting a lot with it. I still don't understand how you can use the same transistor for example to amplify an audio signal, or to act as a switch for ...
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2answers
42 views

Switch Power Supply at 24V using MOSFETs

As title, here's a schematics: simulate this circuit – Schematic created using CircuitLab Is this a correct way to create a power switch or can this schematic be improved? Board will sink at ...
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1answer
37 views

Generator to Main changeover issue RCCB not moving up

RCCB not moving to up position while DG to EB ( generator to mains) changeover. I live in a community where we have almost 1200 apartments in India which will serve power through generators when the ...
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1answer
22 views

Auto disconnect the load while charging the battery

Here is a tentative schematic that would use the battery (3.7V, 3500mAh single 18650 battery) to power the load under normal circumstances. The charger is disconnected at this point. When the AC-DC ...
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22 views

Transistor switch for replacing m5201, Marshall Valvestate30r repair

I have amp in which m5201 are used. It operates on +15V -15V DC and has enable pin voltages that from what simulations I ran ranges from 15V and 10V DC. I would like to replace the chip with regular ...
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1answer
55 views

Best way to switch USB power

I'm looking for a way to switch an USB device's power (a mini waterpump) digitally. I've found some solutions, however I'm not sure what are the advantages/disadvantages of the different approaches, ...
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2answers
51 views

Understanding flyback diodes in an H-Bridge

I am able to understand the use of flyback diodes when a basic low side unidirectional motor switching is done with an N channel MOSFET for example. I also understand the working of H-Bridge ...
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In which region should a MOSFET be operated as a switch?

I have a question about MOSFET switching operation. According to an article: In order to operate a MOSFET as a switch, it must be operated in cut-off and linear (or triode) region. According to ...
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92 views

P-channel MOSFET high side switching, Arduino 5V pin and Vcc connection

In this tutorial, The author makes this weird(to me apparently) connection of 5V pin of arduino to 12 V power supply, and explains itself by: You need to have two power sources - one for the ...
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37 views

Making aysnchronous sequential circuits hazard free

The problem I am stuck at requires me design a hazard free asynchronous sequential circuit for a given problem description. I have followed the routine steps as follows: I have obtained the primitive ...
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0answers
22 views

How to detect charger connected to cut off battery and use externall power

I'm working on project which is supposed to be user friendly. It will usually run on battery and highest expected current draw is around 6A, but usually around 2A. I will probably use Li-On battery, ...
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19 views

Manually selecting which of three ethernet output ports should transmit signal from a single ethernet input, using MCU and transistors?

I have a TV-bench containing three different computer units that all use Ethernet. Although, I only have one measly ethernet output coming out of the wall closest to the bench. Not wanting to clutter ...
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1answer
35 views

Negative Half of Sine Wave Passes Through Off MOSFET

I'm trying to design a MOSFET based switch which allows a sinewave through, however I noticed that when I was simulating it in LTSpice, whenever I try to turn off the FET the negative half of the ...
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1answer
87 views

LM2678 PCB Layout question / review

After my initial question about switching regulators I had decided on trying to use an LM2678 for an adjustable/variable voltage form 5-24V and 5A max with an input of ~30VDC. The application will be ...
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2answers
76 views

LTSpice simulation issue

I am studying a circuit which will charge a capacitor till using a voltage doubler till it reaches a specified voltage value. Then it will discharge through a resistor. An SPDT switch is realised for ...
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1answer
35 views

switching 11 250mA shape memory valves from arduino

I am trying to switch 11 shape memory valves (SMV), which are effectively valves that open by heating a (shape memory) wire by passing a current through it. The SMV require 250mA, and have a ...

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