Short-circuit primary side of a transformer to collect all the spikes at the...
Abruptly detaching a power source from a coil produces a back-emf: this is a well known fact. What I would like to achieve, in my experimentation, is to convey ALL the collapsing magnetic field to the...
View ArticleHow to switch on or off capacitance on a piece of conducting material?
I don’t know if this is the right way of describing it, but I need to activate an area of capacitance on a touchscreen by applying some current to a piece of conducting material like tinfoil. I am...
View ArticleAmplifying Signals to a Certain Voltage
Say I have some high frequency low signals and I want to amplify them to peak at +/-9V or something. Yet the chosen Fully Differential Opamp is only powered at 5V. So even if the Opamp were to go to...
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H-bridge tiny spike?
My high and low side gate measurements to GND show a tiny little shoot through spike. Adding dead time, Zener bypasses over R(g) and from G-S, and TVS diodes does not do anything. The load is 100K and...
View ArticleWhat are the two big transistors on a ESC
Looking at an commercial electronic speed controler for a brushless motor, there is two big transistors on one side. For controling a motor, you have to switch the current on three wire, so you need...
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P-Channel FET Switching Time
I have a question about the circuit shown below. Specifically, I am looking to calculate the time that it takes to fully enhance the PFET and activate 3V3_SW1 after the control signal transitions...
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Question on large signal MOSFET DC Circuit Analysis
The question is asking us to prove that the PMOS is indeed operating in the saturation region. For part (iii) , I’ve found that VG = 6V by voltage divider law. Since IG = 0 , then ID = IS. In other...
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Is this the behavior of a broken mosfet?
I designed this circuit to switch on/off 8 solenoid valves for a programmable dancing fountain that I am building. The GPIO is coming from a Raspberry Pi. VCC is coming from a 12V deep cycle car...
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Voltage shift 5V to 3.3V for PIC16LF145x 3.3V I/O input, several approaches
For USB device detection I need a way to shift that VBUS 5V to 3.3V in order being able to connect it as I/O input pin. The input pin should be high as long as VBUS = 5V, and low as soon as VBUS = 0V....
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Field Excitation of synchronous motor with MOSFET+ Arduino ( MOSFET...
Abstract: I am trying to make an automated system, that monitors the system’s voltage, current, all powers and power factors. This data is wireless sent to a substation(prototype model, imagine=master...
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Selecting a transistor for high-side switching at 5V with a 2A load current
I’m doing a high side switching of 5V 2A load and will be ON or OFF for long time(1-10 hours). Now I’m confused about which transistors should I use ? or MOSFETs ? Do I need heatsink ? I really prefer...
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What is the purpose of the resistor on this MOSFET's drain?
Shown in the schematic below is a typical MOSFET driven by a BJT. I know the purpose of almost everything here, except for R4. I just can’t figure out what the resistor on the MOSFET’s drain is for Is...
View Articleusing a MOSFET to switch a voltage lower than the gate
I’m using a p-channel mosfet to switch a 3.5V load, using a gate voltage that’s ~5V. The gate goes from 5V to 0V, but the mosfet doesn’t start conducting. Did I just fry the mosfet by having the gate...
View ArticleWhat is the dependance of voltages in a MOSFET on its Performance?
The Wikipedia page says that (in context of scaling) To maintain performance, the threshold voltage (Vth) of the MOSFET has to be reduced as well. And also, this paper says, For high performance...
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Using NPN BJT with a P Channel MOSFET to switch 3.3V to 24V
simulate this circuit – Schematic created using CircuitLab I have some 3.3V I/O on a PC Board. When an output is switched on, I need to switch the 3.3V output voltage with a +24VDC and provide by a...
View ArticleMOSFET representation
In my book I often see the N-type semiconductor both drain and source being shown as n+ whereas the p-type semiconductor or the substrate is shown/represented as p only. Why is N-type semiconductors...
View ArticleHow do I energize a 12v relay coil using a 2N2222 bipolar transistor?
I’m relatively new to working with transistors, and I’m having some trouble getting this circuit to work. I want to use an Arduino’s I/O pins (5V out) to energize a 12V relay coil. To do this, I’m...
View ArticleMulti-stage amplifier coupling
For my final project in my electronics course this semester, I need to design an amplifier with a specific set of parameters. Specifically, it needs to have a gain of 100, a voltage swing of at least...
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How does id versus Vds characteristic curve will change if Gate and Drain are...
I was trying to solve this problem 5.19 From Sedra & Smith for microelectronic circuits 6th edition For the below circuit, Find an expression for Vds in term of id, Sketch the graph for Vds versus...
View ArticleDC-to-DC voltage booster mosfet heat problem
I’m tying to understand boost and buck converter designs. Recently I made a prototype of a simple boost converter, used this as a reference. Used parts are as follows: Transistor – IRF3205 Diode –...
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