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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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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
31 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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25 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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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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54 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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116 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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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
53 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
54 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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46 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
62 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
69 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
52 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
42 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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86 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
68 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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36 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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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
42 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
46 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
43 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
41 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
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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-...
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1answer
51 views

Very slow turn-on time BJT (BUV27)

I have been asked to select a replacement BJT for a resonant circuit which uses the now obsolete BUV27. I have selected some based on V(CE) and hFE but all selected types perform a lot worse (low ...
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2answers
71 views

Switching a current source through a MUX

I have a current source of square pulses (0-20 uA) generated by a NI 9265 device. I am trying to build a fast switching circuit using TI CD4051 multiplexer to switch the current signal between ...
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4answers
63 views

Does the switching frequency and ON/OFF time duration of LED affect the power consumption of LED?

I want to drive the electronics consisting a controller with different peripherals on its I/O pins, one of which is LED, with 3V coin cell battery supply. I want to determine if its switching ...
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1answer
119 views

How to reduce noise in SMPS (Switching mode power supply) circuit

I am just using a reference design of SMPS (from Microchip) to boost input voltage from 12V to 90V as the image below: It's working normally but the problem is the noise at the output of 90V. I ...
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1answer
69 views

Noninverting optocoupler with a pulldown resistor

I am using a power MOSFET to switch a solenoid valve. The MOSFET is driven with a optocoupler (LTV-847) to isolate the 12V required to switch the valve from the 3.3V used by the microcontroller. ...
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3answers
74 views

Switching a resistor ladder

Can anyone suggest how i could switch this resistor ladder with the smallest possible footprint. I was looking up analog switches but not sure if thats the right way to go. The circuit tells an ecu ...
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3answers
131 views

How to switch PIR sensor on/off based on photocell result

I've built the following circuit based on an ATtiny85 for a night lamp. The circuit is powered by a 3.7v LiPo battery. I'd like to turn off the PIR sensors when the photocell detects light in order to ...
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1answer
58 views

Stepper Motor Voltage

I am having a problem making a stepper motor run. The problem is that the voltages that I am reading from the motor never reach zero (they move from a high voltage to a smaller voltage) so they never ...
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1answer
40 views

Contact Switch Sparking

Wanting to know if the contacts in switch sw1 spark (see circuit diagram below), I did a simple test and found that there are no sparks even with high amperage. I am unable to explain why this is so? ...
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2answers
281 views

LED Circuit design (4 switches, 1 potentiometer)

I need to design an LED circuit that acts as a switching system. It must meet these specifications. Case 1(Press Button 1): LED 1 ON, LED 2 ON, LED 3 OFF Case 2(Press Button 2): LED 1 ON, LED 2 OFF,...
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1answer
98 views

Interfacing coin cell back up for internal RTC of ESP32

In esp wroom-32 all the VDD pins has a common connection. It includes VDD_RTC too. So in case of power failure if I switch the power between main DC source and coin cell using a mosfet, will it create ...
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1answer
81 views

Turn on/off ESP8266 by a transistor

I would like to turn off and on a circuit by another circuit. I believe that could be easily achieved by a transistor but when there is a voltage regulator and an ESP8266 with wide range of input ...
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2answers
71 views

Understanding Vgs absolute value

If a P-channel MOSFET have absolute maximum values: VDSS = -60 V Vgs = +/-20 V "refering to high switch side": Does this means we cannot switch the MOSFET by the gate driver that ties the gate to ...
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1answer
95 views

Voltage drop when switching FET

I am working on a project which will be switching LED strips with a max of 2A. As a test I have connected a 20W hallogen light. When I try to switch it I get a voltage drop as can be seen in the ...
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2answers
72 views

Choosing Vds value for low-side switch

I want to switch a 24V DC water pump by a 5V DC from an Arduino. I think the best way to do it is by a logic level mosfet low side switching. To do so, the \$V_{DS}\$ value should be 24V or a much ...
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2answers
84 views

Current Sensing problems in PWM-switching circuit

I have the following circuit: simulate this circuit – Schematic created using CircuitLab A simple voltage source is connected to a resistor. The current flow is controlled via an NPN switch. I ...
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1answer
24 views

Transistor Q's: Switching a Positive V when Base goes negative (and the other way 'round)

I thought I knew enough to get this working, but apparently I don't... I have a waveform going between +5 and -5V at audio rates. When the waveform is above 0V, I want to charge a capacitor from -...
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1answer
85 views

How to switch 7 wires with a single on/off slide switch

I am working on a project, where I want to build a raspberry pi into a nintendo 64 console, and be able to switch between with a single switch. By that I mean, I want to be able to use a single slide ...
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2answers
131 views

flyback spike elimination

I have a circuit that is switching a transformer primary winding from 15 volts to ground, through an N-channel MOSFET at 50 kHz. I was seeing occasional field failures and found that every time the ...
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3answers
979 views

Using a transistor as a switch between RX and TX

I have a microcontroller(arduino) connected via its serial output(RX/TX) to a bluetooth module. i want to be able to program the microcontroller when the two are still connected but unless i ...
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1answer
85 views

Bypass LED with switch (why)?

I have a schematic attached that appears to show a switch bypassing an LED, or the other way around. In the working device operating the switch lights the LED and engages (as in turns 'on' a 'normally'...
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1answer
67 views

High-side switch with BJT for 24V controlled by logic level

Earlier I have asked another question and I got very good answers but I couldn't get a solid success as per my size considerations and an unexpected solenoid type change. And I am now giving another ...
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3answers
198 views

Soft latching power switch

I have stumbled upon a soft power switch with low part count on EEVBlog, which I found very interesting for my hobbyist projects: https://www.youtube.com/watch?v=Foc9R0dC2iI Since it uses a PMOS and ...
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2answers
84 views

What is Vrect in a Voltage Regulator?

I'm just reading through Texas Instruments' Application Report on Switching Regulator Fundamentals and came across the half-bridge converter and the formula for both the output voltage of the entire ...
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1answer
96 views

Reduce clicks when switching over cd4066

I make an audio switch on the chip cd4066 (I control using arduino), please tell me how to make a smoother switch without sharp clicks, I need the sound to appear with a small attack and just fade out,...