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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 ...

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22 views

Autofeel light bar mod

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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41 views

MOSFET voltage during switching

I'm simulating a 3 phase inverter of 48 V DC link which is feeding an inductive load (Brushless DC MOTOR), and I'm facing a problem that's ruining my day. Can anyone help me by explaining why ...
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22 views

Switching between multiple lanes to measure resistance

So I have a fair bit of MXM GPUs that have some sort of board problem or another, and measuring each pin vs ground is usually the second step to attempt repair. Oddly, I have an idea to measure ...
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37 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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22 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
35 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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11 views

Generate +V and -V pulses using a polarity-switching 12V long pulse

No idea how to best word the title... I have a +12V signal leaving an instrument that lasts for 10s. Later, the polarity of the signal is switched to -12V for 10s. Basically it's a motor control ...
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1answer
70 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
38 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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19 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
37 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
46 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
51 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
53 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
92 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
49 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
66 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
92 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
53 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
38 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
184 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
43 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
66 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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0answers
29 views

PWM Switching and Current measurement

I have the following circuit: This circuit is created in simulink. It has a voltage source (Vs is 36V, Rs is the source's internal resistance, at 0.001Ω). Resistance R is 1Ω. I want to control the ...
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2answers
64 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
86 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
64 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
48 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
22 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
84 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
117 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
953 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
81 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
63 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
164 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
69 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
77 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,...
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1answer
47 views

Reducing surge current in 5V High Side Switch

Re-visiting a prior question I asked a while back. I have a circuit that looks like the following: simulate this circuit – Schematic created using CircuitLab ... and from what I surmised from ...
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1answer
79 views

powersupply ac to ac

I have recently bought a dcp917S and hoped I finally found a wireless chime that I can tie into my apartment buildings bell system. Since I live for rent there I can't do any changes that are not ...
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3answers
2k views

Is it good practice to run large amounts of current through a MOSFET?

I have been looking for a good way to control the flow of a lot of current in my project. This may at some points be 40-50 amperes at 12-15 V. While relays are a good choice, they are mechanical ...
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2answers
324 views

How to control 12V from 5V using transistor? [duplicate]

i have used BC547 Transistor to stepup from 4.6v but I can't able to draw above 5v from collector, I have given input of 4.6v to base and emitter to ground and collector to output load. but load doesn'...
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2answers
116 views

Can this boost converter circuit work? [closed]

This is my crcuit layout for a boost converter. Please note that I did not draw the load and its connections (for it is something taken for granted!) : In stead of using a controller that maintains a ...
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1answer
65 views

Problem with the fall time of a NPN transistor

I have the below circuit to translate a slow digital MCU on/off (3.3V) signal to a higher voltage signal (range from 12 to 24V). I have a specific attention for the Vin=12Vdc case, the voltage drop ...
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2answers
121 views

FET to be controlled with less than 1V Vgs

I have a simple switch circuit that is powered with a single 1.5V alkaline battery. I want to find a MOSFET(or other device) that will switch on when the battery voltage is applied. I can find plenty ...
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0answers
90 views

Measuring battery voltage, capacitor on drain (nMOSFET switching load)

I've got a schematic to measure a battery voltage using a nMosfet (triggered by a GPIO high level). The voltage is measured at the Probe (see picture). Can you tell me the purpose of Capacitor C1 on ...
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1answer
81 views

Controlling an Array of Motors

I am trying to measure the state of a switch on a vending machine motor (model # BC-D27/28). It has a micro switch on it that has a lead going from COM1 to NC2 when engaged and COM1 to NO3 when ...
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2answers
57 views

Can I switch two 12v sources with 5 pin relay?

I'm installing a stereo in an RV and would like to maintain default behavior of having the stereo receive power on vehicle accessory power/ignition, but also be controlled by a switch in the RV for ...
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1answer
164 views

Can a MOSFET be used for dimming instead of switching a LED?

I have a simple circuit that uses a MOSFET to switch on and off a ~100W LED spotlight (30V, 3A). It works for this application. I have been asked to modify the circuit so that the LED can be dimmed ...
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2answers
85 views

Transistor switch without polarity

I've successfully used an Arduino Uno to trigger Halloween props by closing the normally open circuit on an SRD-05VDC-SL-C relay. I am basically replacing a contact switch and tapping into each prop's ...
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1answer
203 views

How do reduce power supply ripple?

I was given this power supply circuit, please see the image. The problem I'm having is when I connect the 10ohm load (solenoid valve), there is a large ripple when I scope the output. I have provided ...