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PWM with MOSFet- make it linear
there maybe wrong assumption in my question , so forgive me, i am here to learn . So controlling a light(LED) with MCU that outputs PWM, into a MOSFET N-CHANNEL, as described in this little image: so...
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Replacing a switch with MOSFETs
I currently have a 2:1 switch / multiplexer which is being used to switch between two different batteries which are to provide power to a small module on my board. The switch that I am using is the...
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How to switch a Bluetooth module with a P-Channel MOSFET high-side switch?
I am looking for a high side switch to turn a Bluetooth module off when not in use. The module uses 100mA at most and runs on 3.3V. I am using a ATMega328 to talk to the module and it runs at 5V. How...
View ArticleOutput Impedance of BJT/Mosfet amplifiers
I have heard in lectures that the desired output impedance for the BJT/Mosfet Amplifiers is LOW. But these transistors are Transconductance amplifiers ‘by birth’. I mean they give output current...
View ArticleDo MOSFETs have a diode built into them?
I have noticed that a MOSFET symbol has a little diode in it (or at least what looks like a diode). Does this mean I do not have to worry about using a diode in a circuit that runs a motor using one? I...
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Floating charge pump for high side N-channel MOSFET bias
This question is derived from this one. I’d like to keep gate on for an indefinite period of time (100% Duty cycle) and for that I’d like to use charge pump since idea with relay is not attractive. The...
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ckt flicker removed with hand touching drain
I have a boost circuit to control LED light. The circuit PI is controlled by microcontroller through software. This circuit works fine till some current at load but as I increase current after some...
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Achieving higher current at the lowside MOSFET to pulse LED
I have attached the following circuits which i have been developing overtime. The OBJECTIVE is to get as high as possible a current at the gate of the MOSFET (VF1) to achieve faster pulse times of the...
View ArticleNEC 2SK3919 MOSFET replacement [closed]
A few MOSFETS have failed on my motherboard. And I was looking on the web to find a replacement for the ones that have died. The ones that are currently on my motherboard are NEC 2SK3919. The only...
View ArticlePowering and controlling multiple 12V LED strips with Arduino LilyPad USB
I’m trying to use an Arduino Lilypad USB to control several separate 12V white LED strips. I am however struggling to work out how to power them. The LilyPad only operates at 3.3V and I thought a...
View ArticleRise time and fall time calculation of an integrated switch?
Following the analysis regarding the selection of buck converter for my application (Buck converter efficiency Vs load current:). Now I am trying to estimate the power dissipated in the integrated...
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Theory of operation for discharging filter capacitors with a MOSFET switch...
Our teaching assistant showed us this circuit, saying that the MOSFET acts as a switch. When the power supply is OFF, the MOSFET allows the filter capacitors to be discharged via the switch circuit. I...
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Mosfet small signal input resistance from source
Considering the T model of MOSFET for small signals I want to obtain the input resistance from source to gate. simulate this circuit – Schematic created using CircuitLab The current flowing upwards...
View Articlecan NPN transistor be used when sinking current?
so to give a little bit of background, I want to experiment with led matrixes. I have multiple Arduino Nano boards, and have done small projects (9 LED bank with simple animations). So I know that each...
View ArticleUse of MOSFETs body diode
I have an N-MOSFET array IC and I don’t need to use all of them, but I do need to use a diode. Is it OK to use the body diode of one of the MOSFETs as a regular diode to decrease component count and...
View ArticleIsolator for MOSFET switching
I am operating power MOSFET at 100khz. Signal for gate is given by MCU which is then given to MOSFET driver and then fed to gate. I want to build MOSFET driver can anyone help me in specifying the...
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FET and BJT transistor question
We have the circuit in the figure BJT transistor has the parameters β=80 and the JFET transistor has the parameters Vp=-4 Volt and Idss=8 mA; Vgs=-2.6 Volt and Ids=1 mA We have R1=470 Kohm ,Rc=3.6 kohm...
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Why do N-channel MOSFETs have a voltage drop when load is connected on source...
I read how MOSFETs work, although there is this thing I can’t understand. To make things simpler let’s take only n-channel MOSFETs into account. Normally, the load is connected on the drain side, like...
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MOSFET switch replacement not working
I’m using a PNP MOSFET to replace a physical button. When I ground the lead I’ve attached to bypass the switch, the action I need activates (a notification light comes on – it’s the activator button on...
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power mosfet switching basis
I have a really simple question. I have this simple circuit. This is a converter, where the power-pole is made as a power mosfet transistor plus a diode. I did not get the Turn-on behaviour as shown...
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