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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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80 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
45 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 Vds value should be 24v or a much lower ...
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2answers
28 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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0answers
20 views

toggling current mirror circuit

I am designing a circuit to sample the voltage from different battery cells that are serially connected (for a Battery Management System). The whole point is to measure the voltage of each battery ...
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1answer
76 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
101 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 ...
4
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3answers
886 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
77 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
58 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
119 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
49 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
65 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
43 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
77 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
105 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
111 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
59 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
92 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
86 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
77 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
52 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
115 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
79 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
113 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 ...
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2answers
173 views

High-Power Switching using MOSFETs

For a project, I need a means of switching a high-current circuit between two inductors. The purpose is, each inductor serves as an electromagnet, and they are switched every 15s or so in order for ...
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2answers
33 views

indicator of mosfet switch, optimized?

I want a visual indicator of my MOSFET's switching state, so I've designed this circuit with fairly generic smd parts and simulated it a bit to see if it performs as I've expected. It seems okay up to ...
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2answers
51 views

Cheap and simple way so switch on and off based on voltage, with hysteresis

I'm playing a lot with solar powered systems using ultracaps for energy storage. I'm also powering some small ~3.3V systems directly from LiFePO4 cells, charged by solar power. In both cases I'd like ...
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1answer
73 views

Switch operating at particular touch IC voltage [closed]

Is there any circuit to perform such task more efficiently? I am trying to control a small motor (like a smartphone vibration motor) with specific outputs from the touch IC, so that it can be turned ...
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1answer
762 views

Does a TIP120 transistor have an internal resistance when switched on?

I'm having an issue with a TIP120 I'm using limiting current flowing through it. I'm using the TIP120 to switch on/off a 12 V electromagnet. The circuit is working, but it appears the TIP120 is ...
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2answers
90 views

Transistor 2N2222A wont accept base input from arduino

I'm New in electronics. I read "Robot Building for Beginners" book and I'm trying to make a line follower circuit. Instead of LM393 and 2N2907A I'm using arduino nano and 2N2222A. Here's my code: <...
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1answer
44 views

Slew Rate controlled MOSFET switch

This circuit controls the rate at which M1 switches on using the current mirror consisting of Q1 and Q2. A digital pot is used to control the current through Q2. The circuit works great in simulation, ...
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1answer
78 views

How to switch dummy load circuit on/off with pwm?

I built pretty much the simplest dummy load for testing batteries I found on youtube (EEVBlog #102) , but I modified it little bit. I used 0R1 resistor, because I needed bigger currents from battery (...
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3answers
42 views

Decade voltage divider switching

I have a decade voltage divider used for range switching in my project. I need a way to switch the multiple different voltages that the divider creates into one output, sort of like a multiplexer ...
3
votes
3answers
247 views

Reduce MOSFET switch off time

I am using this switching circuit to switch a lamp. I am controlling a rising slew rate at Vout (from 0-Vcc) that is adjustable by setting R2 with a poteniometer. It's not necessary for my project, ...
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1answer
82 views

Noise problems in current sensing

I have the following circuit: simulate this circuit – Schematic created using CircuitLab I am using a motor from an electric bike, as a generator and I am rotating it using a drill, to test ...
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2answers
123 views

Slew Rate Adjustability

A SPST switch connects HB1 and HB2, to control a lamp connected to HB OUT. I am looking into modifying this circuit to make the slew rate adjustable when switching the output to VCC (around 12V). I ...
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4answers
106 views

Circuit to get a short at 0 volts and open at 3.3/5 volts using transistors

simulate this circuit – Schematic created using CircuitLab This is the situation I am trying to solve. I am considering using a transistor, but am not 100% sure. When I get a 0 volt input, the ...
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1answer
60 views

How does the inductor have an initial condition in this circuit?

If the initial current in the inductor is \$i(0^+)= 0 A \$ why is it that when the switch occurs the initial voltage in the inductor is \$ V_L(0^+)=121.4 V\$
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1answer
161 views

Connect two different sources with two Digital Ouptuts using an Adam 4055

I would like to operate an Adam 4055 module to control two different applications having their own power supply. Adam 4055 is Digital Input/Output control module over RS-485, I use only the DO part ...
1
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1answer
197 views

Latching Press-on / hold-off toggle switch circuit. Works on breadboard not on PCB

I followed a schematic and mocked up a Latching toggle switch with NAND gates. (see picture below for what I followed) (Source) I have mocked it up onto a breadboard. Using the exact same values of ...
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0answers
38 views

High frequency switching node in DCDC converter

There are some nodes with high frequency switching contributing to EMI in Flyback and Forward converters, which should have minimal copper area to minimize the EMI. Here we see the Forward high ...
6
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1answer
608 views

How does a “speed up capacitor” work in Schmitt trigger?

Hello I'm trying to understand how adding a capacitor across R2 in below circuit increases the switching speed. I don't see how C2 supplies charge to C1. With the additional capacitor C2, it seems ...
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votes
4answers
2k views

Is this a sensbile way to switch a 12V line with 3.3V logic

I am just starting to learn about making electronic things, so this may be a foolish question. I think this is adequately different to similar questions here. As a first project I am working on ...
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1answer
37 views

Can an N-ch JFET switch be positive-common-source?

I'm considering switching options for an HF (3-15 MHz) tuner network. Pin diodes are interesting but their surrounding control circuitry is somewhat inconvenient, and they require relatively high ...
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2answers
63 views

Simulink battery model with buck converter

I have created this model in simulink: Vfc and Rfc are the equivalent of a battery, and the battery is connected to a load R, through a buck converter. The buck converter is implemented with a mosfet,...
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3answers
97 views

How can I have one LED go on, when another goes off

I have a scenario where when one switched electrical path for example a tail light (LED #2) on a motorcycle is switched off, I want LED #1 to go on. When power is switched on to LED #2, then ground ...
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1answer
41 views

Soft switching drain resistor in mosfet gain stage

I would like to switch between two drains resistors in a high voltage (300 VDC) audio LND150 gain stage. I opted for a BJT instead of a MOSFET, because the MOSFET parasitic capacitance was too high ...
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1answer
88 views

Driving a 35V PMOS circuit from a Grounded/Floating input

I have an application where I need to switch a contactor on and off using a spare output of an off the shelf Battery Management System (BMS) The input is the signal coming from the BMS, while the ...