Tagged Questions

3
votes
5answers
119 views

MOSFET is not turning off when the gate terminal is grounded

This figure shows a small portion of my circuit: The maximum Vgs of the MOSFET is 20V. The MOSFET is initially turned on and now I want to turn it off. For that I am grounding the terminal A to ...
2
votes
1answer
245 views

Voltage regulator with op amp(negative feedback) and MOSFET

The schematic above is a very good voltage regulator, excepting the high power dissipation for Q1 (also I'd use an NPN instead of a PNP). Can I replace Q1 and Q2 with a high current n-mosfet and ...
1
vote
5answers
321 views

MOSFET or Transistor for using as switch for audio signals

I was wondering which component is better for using as voltage controlled switch for audio signals (e.g. music signal from mp3 player). Should I use MOSFETs or transistors? The max rail voltage is ...
3
votes
2answers
308 views

BJTs versus (MOS)FET to switch a load from a microcontroller

I would like to know what are the reasons for choosing bipolar junction transistor (BJT) versus a field-effect transistor (FET) (MOSFET or a JFET) to switch a load from a microcontroller. In our ...
4
votes
2answers
163 views

Signal volume LED Array

I am done a google search on this and have come up blank. What I have is a signal/sound being fed through a wire that ranges from (0-9V). When the volume is low, and i need 1 or 2 leds to light up, ...
3
votes
4answers
371 views

Quiescent power of BJT vs MOS transistors

This is a question about the power necessary to control a transistor circuit, i.e. the base current in BJTs vs. the gate current in MOSFETs. Why is there quiescent power dissipated by base currents ...
3
votes
2answers
2k views

What is the formal definition of Quiescent Point?

What is Quiescent Point? Is it necessary for it to be related with any V vs I , I vs I, or any such characteristic curves intersection point?
2
votes
1answer
553 views

What's the 2N3904 / 2N3906 FET equivalent?

Is there a generic low-power switching FET that's multiply sourced, generally readily available, most simulators already have models for, etc.? I'm not looking for FETs that have similar electrical ...
1
vote
1answer
230 views

Features values of typical BJT/MOS transistors

Is there a page that lists the values of all the features of typical BJT/CMOS transistors? e.g. ON-resistance, gate/base capacitance, amount of power the D-S/C-E junction is able to hold etc. Of ...
20
votes
2answers
777 views

When to use what transistor

So there are several types of transistors: BJT JFET MOSFET Combine all that with the various flavors of each (NPN, PNP, enhancement mode, depletion mode, HEXFET, etc) and you've got a wide array ...
13
votes
4answers
5k views

When is a MOSFET more appropriate as a switch than a BJT?

In my experimentation, I've used only BJTs as switches (for turning on and off things like LEDs and such) for my MCU outputs. I've been repeatedly told, however, that N-channel enhancement-mode ...