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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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how to fix output voltage of an NMOS switch with changing load characteristic?

In an NMOS low side switch the output voltage at drain depends on the operating point decided from the Id-Vds curve and load line. According to my understanding, for a low side switch with Vds ...
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1answer
94 views

Push button to only turn off circuit

First off I have no background in electronics but have been coding since decades and have successfully built things around an STM32 blue pill. Now I am trying to build a battery powered circuit which ...
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1answer
129 views

500v generation with 24V, request for current limitation

I am generating 500V from a 24V source. Attaching schematics. This circuit is generating stable 500V. I am attaching a load of 7 kohm. In the schematics the buck regulator is supplying 19V to the ...
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1answer
152 views

Is it possible to use a NPN BJT as switch, from single power source?

I'm attempting to build the following circuit to better understand how to use a NPN BJT as a switch. What I've Tried I'm calculating the current across the LED (in order to light it up) as: ...
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1answer
60 views

Connecting an IC to LEDs - would I use a transistor?

I have this breadboard circuit, which is basically a 65C02 CPU that has 16 Address pins. I want to wire these up to LEDs. Below, I've connected them directly, which is likely all kinds of bad (Too ...
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1answer
26 views

Power button behaving as OFF-(ON) momentary switch rather than latching- Troubleshooting

I have a device which doesn't turn on normally when you press the power button like it did before. You have to keep holding it down for it to remain on. As soon as you let go, it turns back off. In ...
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2answers
77 views

PCB GND Guard ring

In my design I am using the step-up converter TLV61046a. As this is the switching device, I would like to maximize EMI reduction. I would like to hear your advice if this GND guard ring in my layout ...
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74 views

12 V pulses with 100 MHz repetition rate

I have to control an high impedance load (> 25 MΩ) with 12 V pulses with maximum 5 ns of width and a repetition rate of 100 MHz. I can generate the pulses with the required shape using an FPGA ...
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1answer
73 views

Serial line switching through a transistor

I want to switch my RS-232 TX pin.For this I am using NPN transistor in between the TX line in such a way that the collector terminal is connected to controller side and Emitter to external side. ...
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1answer
105 views

Simplest way to switch inductive load with arduino?

I'm trying to switch (just on/off) a 3.7V motor (coil resistance 2.2 Ohm) and a 6V motor (coil resistance 8 Ohm) with an arduino mini. And I have trouble finding an universal way to do so. What I ...
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2answers
56 views

Problem with stacked power mosfet simulation

I'm trying to build a Circuit Lab simulation of a stacked power mosfet pulser as described in this paper. The simulation runs for 10 ms. After 5ms, the switch flips and the voltage at 'StageOne' drops ...
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3answers
100 views

UVLO for Energy Harvester circuit

A good background on the problem can be found in the document: (Under Voltage Lock-Out Design Rules for Proper Start-Up of Energy Autonomous Systems Powered by Supercapacitors). The above document ...
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4answers
79 views

Will switching a LED on and off at a said frequency reduce or increase heat loss?

In my case, a 50W 34V LED is being used to light a small box. To reduce heat generated by the LED, we are switching it on and off at 50Hz. But I was wondering will this actually help? In the case of ...
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1answer
50 views

Fast switching with RTL inverter

I have for some days worked with an RTL inverter and an totem pole drive to drive a high voltage MOSFET. And I am happy with the result except for one thing the rise time on the inverter output (from ...
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2answers
83 views

Fixing conmutation for high voltage switching with power MOSFET

I have an issue with a charge circuit for a capacitor as load. I want to switch approximately 400 V DC to charge a 1000 µF 600 V capacitor. I'm using a power MOSFET for this application. I need it to ...
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29 views

Switching between two connections - adding LEDs to car reversing light circuit

I am doing a DIY project on my car and need some help. I have 2 LED COB on the back of the car, which is to be used for 2 different things: If I put the car into reverse gear, then the LED comes on ...
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1answer
39 views

NPN Transistor Switching 12V - grounds with different potential

I'm struggling with a NPN transistor switching problem, and in the process I've burned out a board elsewhere in my machine. Electronics is not my strong suit. I want to use a 5V signal to switch 12V. ...
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86 views

Finding R, C and Switching Frequency [closed]

I need to find R,C and switching frequency of the following circuit such that Switching Frequency is low as possible with given Vu and VL. Also how can I improve the circuit so that it can reach it'...
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2answers
52 views

How to determine maximum switching frequency of power modules?

Power IGBT and MOSFET modules give some datasheet values that look like they could be used to calculate a maximum frequency, but I'm not sure how to interpret them to do so. The datasheets generally ...
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1answer
39 views

Using P-MOSFET with Gate and Source have same voltage to protect reverse current

I have a question when I am working on MP2639A 2-cell LIPO charger (+8V4) from USB +5V. The recommend schematic uses P-MOSFET to protect reverse current from Load back to a USB plug. taken from ...
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3answers
91 views

Inductance value of an Isolation Transformer

There is a small isolation transformer 'L1' of 1:1 ratio as shown in the image. A 0-24V, 75kHz square wave is applied from push-pull mosfets stage at the 'V_SW' input of the circuit. I want to find ...
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1answer
31 views

Sharing a HD44870 display between multiple controllers

I have an existing third party system that has a HD44870 compatible display used for output. This third party system cannot be changed (for a variety of reasons), and I need to retrofit a device to ...
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0answers
55 views

Snubber for Relay Contact Switching Resistive Load

I am working on a redesign of some circuit boards and am looking for a way to save space and potentially switch to surface mount parts. Some of the largest through hole parts in use are for an RC ...
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2answers
104 views

Advice on choosing components for a flyback arrangement, for switching inductive loads fast

I have a bank of x6 MOSFETs (SUG90090E) connected in parallel, which I am using to switch a current of maximum 30A through a coil (resistance 1R and inductance 1mH), and am looking for some general ...
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2answers
2k views

Why do BLDC motor (1 kW) controllers have so many MOSFETs?

I have a 1 kW three-phase BLDC motor from China, and I was developing the controller myself. At 48 Vdc, the maximum current should be about 25 Amps and a peak current of 50 Amps for short durations. ...
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1answer
78 views

What is causing these switching transients on a 3 phase motor driver?

One time I built a 3 phase motor driver, which works quite well in the original configuration. Recently, I changed the physical layout to this rectangular form factor, and now it has quite large ...
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1answer
40 views

Induction Motor Switching Surge

I would like to ask a question related with induction motor Whenever I switch ON & OFF a motor, a small voltage (3-8 V) produced at the metal surface where the motor is attached. I figure out ...
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0answers
26 views

How to turn on & off 50W LED when already using a driver according to limit switches?

I have a 50W UV LED that is going to be installed on a UV printer's head. The printer's head raster, as printers usually do. I would like to turn the LED on only when reaching the printing surface and ...
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2answers
23 views

Switching system is not working as intended, unless I use my meter prob whose Negative is on ba3 negative , how can I fix it?

simulate this circuit – Schematic created using CircuitLab I want a circuit that could turn on a system and as well turn of that system, and sometimes work as an automatic switch pls guys take ...
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2answers
77 views

Replace mechanical switch with electrical switch or relay

I have a remote controller for a portable heater, and I am working on a small project to be able to control the fan on/off from an arduino with Bluetooh HM-10 module. I thought a solenoid might work ...
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3answers
119 views

Switching 240VAC 1A max from 5VDC

I'm planning a device that can switch a 240VAC 1A current - most likely 0.5A but it's nice to have the head room. A relay seems the most obvious choice but given the low current it seems over the top ...
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2answers
168 views

Ground something, for a short time

I need some simple solution, for grounding an AdKey for a short time lets say 200ms, only once, on each power on. I don´t know the exact needed time so it would be nice if i can change the time with ...
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1answer
57 views

Latching switch, momentary pulse output when switching on

I'm really struggling to find a simple circuit that'll give me a pulse (~1s) when switching the circuit on. The latching switch can't be changed and already controls other circuits, and the new module/...
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2answers
60 views

Row Column Matrix Problem with Flyback Diodes

So I had a simple row column matrix which I am driving with mosfets to power solenoid locks like this: GC is ground via 1.5k resistor C is 24V via 1.5k resistor And these are the connectors: ...
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3answers
52 views

Multiple input to single output converter and vice versa

First question so please forgive any mistakes. I'm trying to design a system by which multiple LEDs are controlled by multiple switches, but without using as many wires as there are switch/LED pairs. ...
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0answers
69 views

How to reduce spike in Power Supply and GND (SCR + Ignition Coil)

My circuit: Signal coupled in power supply (3.3V) of STM32F103 during spark: Is there any benefit to using this diode (circled in red) or not (without this diode the snubber circuit will start ...
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2answers
85 views

What is the turn-on and turn-off condition of the npn-transistor?

Following is the circuit I have been analyzing. My intention is to calculate the turn on and off condition of the transistor Q1. R1 and R2 (10 kΩ each) are internal to the transistor. simulate this ...
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1answer
84 views

Switching high voltages with MOSFET at high frequencies

I need to rectify 220V 50Hz AC power to obtain 48V DC output voltage. Up to 40A current can be drawn from the DC side. 10% ripple is acceptable on the rectified voltage. I am considering two ...
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1answer
59 views

Battery switchover circuit when battery is being charged

I would like to use two LM5050 in a typical redundant supply configuration for wall adapter and a battery. My concern is that when wall adapter is connected battery voltage goes higher because of the ...
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0answers
93 views

Power source switching circuit - 60-80V sources

I have a circuit I'm working on that has two power sources, one varies between 40-60V, and the other is 72V. The 72V power source will typically always be on, and the 40-60V source may be on or off. ...
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1answer
94 views

Switching Mode Power Supply Fluctuating Output

I designed a switching mode power supply using LNK-562, I share the circuit schematic below. Note that NTC, fuse, and the input filter inductor is replaced with shorts in the real circuits. I am ...
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0answers
42 views

Opto-coupler and switching digital pins

I'm a total noob when it comes to the use of opto-couplers, but I'm trying to connect up a couple of digital pins between an ESP32 and a small voice module. There are two pins that I need to switch ...
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88 views

Autofeel light bar mod [duplicate]

I purchased an Autofeel 30 inch light bar that has 4 rows of LEDs. I have seen this bar advertised under a number of different names, but as far as I know it's the only one with 4 rows of LEDs (they ...
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2answers
48 views

P-Mos switch high side

I'm trying to switch P-Mos given that: Vcc > Vgs max Enable_output is 0V or 3V I'm switching both GND and VCC on purpose. 4. 8.4VR at 2uA ! The questions: When Q2 is off, what is Vgs at Qsp1? Is ...
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1answer
64 views

Switching IC via FTDI232 DTR and transistor

I am trying to switch an IC on/off via the DTR signal pin on an FTDI232 USB/TTL Serial converter. Basically during the flashing of my ESP8266, I need to be able to power the IC off and then on again. ...
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1answer
51 views

Mosfet switching

I'm implementing mosfet switching circuitry using the P channel enchancement mode mosfet DMP2305U.Where Vs = 3V and Vg is using as control voltage and toggleing between 0 and 3V . When Vg is zero ...
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1answer
73 views

Switching a USB HDD on and off

I have a PC which I backup to an external USB3 HDD drive from time to time, I manually connect the drive whenever I "remember" to do the offline backup. I don't want to keep it connected all the time ...
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1answer
45 views

Use rotary switch potentiometer from amplifier as main power switch

I am working on a battery powered audio project that uses a cheap amplifier (PAM8403 5V Mini 2*3W D Class Digital Amplifier Board). The volume can be changed using a rotary switch potentiometer. ...
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0answers
23 views

Ground issues when switching AC with 2 MOSFETs

For a DIY smart home project, I need to switch 24VAC from a microcontroller (in sporadic 200ms pulses, drawing 1.3A, to switch a bistable latching relay). The most cost-effective way seems to be 2 ...
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1answer
43 views

Electronicaly switching parallel LC circuit components

Let's say I have mentioned circuit and I want to be able enable/disable one of the 1uF capacitors to change the frequency of the LC circuit. I would like to do this electronically with a micro-...