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MOSFET

I am using a MOSFET with a remote control momentary switch to turn a 1.5v mini DIY motor, which in turn controls the movement of a tiny plastic mouth to simulate speaking.   My issue is this.....the MOSFET I have calls for DC 3v-5v powersupply.   When I use 3v, the battery drains very quickly.   I've found no such thing as a SMALL 5v battery in the U.S., so I switched to 6v and it works just fine, but I am worried I will damage the MOSFET.   Here is the spec info from the seller (we are using Version A - DC3v-DC5v).  Product Description 1. Working Voltage: A: DC3V-DC5V     B: DC3.5V-DC12V  Optional                                   2. Max Load: 1A (have better load less than 700ma)  3.  Working Frequency: 433.92MHz   Working Current / Quiescent current : 7ma/H  4. Frequency Deviation: more or less than 0.2MHz  5. Working temperature:  -20'C- +80'C  6. Receiving Sensitivity: ≥-110dBm  7. Output State: A: Input DC3V-DC5V  Output DC3V-DC5V 

Topic by croswords    |  last reply


Paralleling MOSFET's? Answered

Can you parallel 3 MOSFET's by wiring Q1s gate to Q2s source then Q2s gate to Q3s source, parallel the sources and drains of all 3 MOSFET's together then add some diodes (the diagram is below)? They will be oscillating so no balancing resistors are required.  

Question by The MadScientist    |  last reply


mosfet similarity Answered

Hi, I am trying to build this,  but the mosfet is discontinued. Can I replace it with TK15J60U(F) and still have a working circuit?

Question by jbaker22    |  last reply


Mosfet Question

Hey guys, I am doing the arduino controlled rgb leds (1 watt leds) project and I am going to use mosfets for the leds. I ordered 3 IRF540 mosfets, 1 for each color of leds (Red, Green, Blue). the arduino is going to use pwm to control the leds but the arduino can only supply 5V at 40mA max. The mosfet have gate-source voltage of +/- 20V and a gate-threshold voltage of 2.0V to 4.0V. Do i need a driver circuit between the arduino and the mosfets and if not is 5V sufficient to run the mosfets in pwm? If i do need a drive circuit, does someone have a schematic since i am inexperienced at electronics? Would i need a heatsinks for the mosfets? thankx for any insight...

Topic by Slisgrinder    |  last reply


MOSFET question

Greetings everyone, I've been trying to learn how to use MOSFETs lately, and I've reached a confusing speed bump.  My main objective for a first project will be to simply use it as a switch, but I'd like to really learn them and not just mimic others' work.  The MOSFETs I have are mostly IRF740, IRF540, and IRF240.   Are 'Enhancement' and 'Depletion' modes of MOSFET operation, or see they separate components?  In other words, can I use any MOSFET in either enhancement or depletion mode? My brain and I thank you!

Topic by Electron_flow    |  last reply


MOSFET Transistor? Answered

Hey Instructables. I am working on a project requiring some MOSFETs but they have to be smaller than the Radioshack IRF510's (http://www.radioshack.com/product/index.jsp?productId=2062618). I think I found some ones that are smaller (http://www.jameco.com/1/1/195-bs170-transistor-bs170-n-channel-mosfet-60v-92.html), but do they have the same functionality? What I mean is, will they work the same way? I believe they will, since they are both labeled as N-Channel MOSFET Transistors, but its always good to check. Thanks in advance!

Question by Adum24    |  last reply


MOSFET Deisgn

I just designed (if it works out) a super efficeint Beam Solar engine that works at low voltages. Before I post it I want to ask a few questions to see if I need to revise my design. 1) MOSFETs work on voltage, no current, right? 2) Do MOSFETs have a voltage drop, like biploar transistors have a voltage drop of about 0.6 volts? EDIT: I got a new design that I want you guys to evaluate that doesn't use mosfets. It's incredibly simple and I want to know what you guys think. How it Works: The solar cell energizes the transformer coil while turning on the transistor. The transistor shorts the circuit and then the transistor turns off, then it repeats creating pulsed dc that drives the stepup transformer. I chose this design because there's very little components and there's no voltage drop across the transistor to the transformer. Theoretically this could run on as low as 0.7 volts, which is good for BEAM robots.

Topic by guyfrom7up    |  last reply


substitute of a mosfet??

I'm in 6th sem EC and my group is making an project on auto intensity controlled street lights. In the circuit a irf520 mosfet is required which we are not having. so if any other transistor could be used in place of that, please tell.

Question by deepali gupta    |  last reply


Open circuit mosfet?

Im trying to help out a friend by doing some research for him.  Im in over my head being a newbie to electronics.  I was wondering between P- Channel and N-Channel mosfets which ones started out as open circuits.

Question by jkutz    |  last reply


Best MOSFET for a sstc? Answered

Which MOSFET is best for a sstc in the circuit given? If the input voltage is 140-220v. And is the diode(MUR1560) near the MOSFET(D4 & D5) necessary? Is there any way to exclude that?, By using any other MOSFET?Any MOSFETs with in build diode, so that i wouldn't have to put an external diode? or could a simple in4007 work in place of it? Any other diodes which are more easy to obtain?

Question by jasshopper    |  last reply


How to wire a MOSFET?

I have some CCFL's that i want to switch on and off with an Arduino like board. I think i have wired them up right but it doesn't seem to be working. I'm using the IRF530 MOSFET (data sheet here: www.rapidonline.com/pdf/47-0522.pdf) and i'm powering the CCFL's from an old PC power supply.

Question by cheesemarathon    |  last reply


Supercapacitor + Solenoid + MOSFET?

I am designing a coilgun with three stages. Each stage has 1mm thick copper wire, with 32 turns across 32mm of length (1000 turns / meter). There are 4 layers with the same wire, length, and number of turns on each stage. Each coil will be powered by a 100F 2.7V supercapacitor (assume charging circuitry has been implemented). With those values, I have calculated that the resistance of the coils is about 0.1 ohms. With a 2.7V capacitor, I can get almost 25 amps of current through the coils, resulting in a total magnetic field of about 0.1 tesla. If I wire the coils in parallel, I get a resistance of 0.05 ohms and 420 amps through the coil, resulting in a field of strength 2 tesla.Now, the problem I am running into is shutting off the current at the right time. I found a MOSFET used for 3D printers that says it can handle up to 280A (360W at 12V or 720W at 24V). If I use thinner wire, I can decrease the current to below 280A which I suppose is powerful enough for the coilgun.Since I will be using an Arduino or similar microcontroller to manage the timing for the coilgun, would I be able to use this MOSFET (linked below) to shut off the current using a signal from the Arduino?https://www.aliexpress.com/item/33059582602.html?s...

Topic by BiaxialObject48    |  last reply


BJT vs MOSFET? Answered

-- background: In my perpetual pursuit for designing the best, cheapest, & best performing flyback (line transformer) driver, I've decided to try out some big BJTs, which appear to have higher voltage & current ratings @ considerably lower cost. In the past, I have tried MJE3055's, which work OK, and allow the generation of thin blue arcs from a 12V supply for a few minutes until the transistor dies due to high voltage kickback or overheating. The FDP33N25 gives good results but is somewhat unreliable at 24V. So I decided to give these alluring "PHE13009" 400V 12A rated NPN BJT's a try. However driving the transistor adequately seems to be the problem. (I didn't realize these transistors would require like 5A base current w/ only HFe of 2!) It seems like almost all the "good" driver schematics utilize large $$$ FETs or even IGBTs, but almost every CRT, plasma globe, and ballast (SMPS) I took apart seem to prefer high power BJTs probably due to this exact cost difference. I was only able to get simalar performance to my 33N25 MOSFET when I stuck an additional TIP120 in as an additional darlington stage, which worked very nicely (white hot arcs) for about 1 second, then it popped! :( Since the collectors are tied together they are all exposed to >200V transients, I am sure that's what killed it. I substituted that transistor for another PHE13009 to see what would happen and with a third driving stage (2N2222) I could get somewhat acceptable results but I know I can do better. >:) - My actual questions:  * The GDP of this transistor is 40MHz, seems fast to me. (certainly faster than the 2MHz GDP of the 2N3055 which works well in my slayer exciter.) and MOSFETs have significant gate charge. ECE2630 glossed over transistors mentioning BJTs are faster, (small signal ones, anyway :P ) and some internet sources agree, but I am finding lots of sources saying the opposite! What's the deal? Which one "faster?"  * How to traditional BJTs compare to IBGTs? Which are faster/better? The datasheet for this transistor explicitly mentions its use for "high frequency ballast and switch mode applications" which implies that it is well suited for my needs. It also includes a several inductor test circuits, but other than that the datasheet is pretty bare-bones.  I'm actually a little disappointed the HFe is so low (around 2-3) @ >10A. I may require more windings on my primary and a 48v supply. (not ideal) * I know I will dissipate a little more heat due to the base current, and something I didn't consider was heat dissipated in the resistor biasing/controlling the base. (like 12V at several amps just to drive the damn thing!!) so it is worth the cost benefit of $0.5? Is there a configuration I could use that makes driving the transistor easier?

Question by -max-    |  last reply


how to stack MOSFETs?

I am using some MOSFETs to power transformer for an inverter but the MOSFETs get hot some said stack them now do i just go SOURCE to GATE and connect all out puts

Question by dufniall89    |  last reply


Are resistors need with mosfet?

I posted a very similar topic a couple minutes ago but I'm pretty sure noone can see it, so I'm copying and pasting the body. I just want to check this before I blow up my mosfet (I've never used mosfets before) Is it correct that you don't have a resistor from the voltage source to the gate (unlike bipolar transistors) Should or shouldn't you have a 1M ohm from gate to ground? Let's say I'm driving a mosfet from a 555, should I have a resistor from the output pin to gate? I think the schematic I'm reading just through a mosfet in where a bipolar use to be without changing that resistor.

Topic by guyfrom7up  


Mosfets and zener diodes?

Backstory: I'm in the middle of modifying an ac welder to dc and plan on doing my first ibble using it as the topic.   Sorry for writing a book here,  I didn't want to be too vague and just confuse everyone.  I have most of the parts for the DC power supply,  I'll be using a bridge rectifier,  and LC filter consisting of 4x22000uF 63v caps, and a self wrapped torroid inductor.  It'll also have a bleeder resistor if some undetermined resistance. I'll be adding the rectifier to the secondary output,  and adding the caps in parallel with the gun and work leads,  and adding the inductor to the work lead.  It occurred to me today that by making this mod,  the gun tip will be hot for some time until the caps are drained by the resistor.  It's not the end of the world,  but I'd like to see if I can figure out a way to mitigate it with your help.  In its current state,  the trigger on the gun closes a circuit which contains a relay.   That relay closes the circuit on the primary coil of the main transformer,  and starts producing the stepped down ac voltage for welding..  I want to do 3 things: 1. Initiate a short across the relay supply to the relay drain and closing the transformer circuit until the caps reach a certain voltage. (Nice to have but not critical) 2. Insert a switch between the caps and the gun, it should be closed when the relay is closed (must have) 3. If I can get both of those working,  I can have the bleeder resistor on an open circuit while the welder is on,  and close it when is turned off to start bleeding the caps. I think all three of these can be done with some combination of resistors and transistors.  For the cold tip,  can I use a mosfet?  FDP030N06-ND looks pretty close. The ac supply is 38v 60A(low) or 19v 120a(high), I expect the dc to be close.   The caps I have are 63v though.  Will the extra few volts burn out the transistor since it's only rated for 60v? I know nothing about zener diodes,  but was reading that they should be used to protect the mosfet from back voltage caused by induction in the circuit. How do I size it? For charging the caps,  I believe I can tap the main power to a transistor which classes a circuit bridging the -/+ of the caps, with a resistor to only allow voltage to pass once it reaches a certain potential. If there is enough voltage it would trigger the gate on a transistor and close the short across the transformer relay.  Would this work,  am I over simplify ing it? Last,  to drain the caps when power is off,  I think I can use a transistor to be open while the main power is on,  and close when the power is shut off, letting the bleed resistor is doing is job.   Do they work like this?  What type would it be that is normally closed,  and opened when the gate is powered?  I'll see if I can create a circuit diagram and attach tomorrow,  but please bear with me,  I'm a total noob to electronics, it may be pretty bad.   

Question by DonaldF9    |  last reply



The classic IRFP250N vs FDP33N25? Which one is best for high power SMPS? Answered

I have an idea to start selling some powermax singing arc kits. In the kit I plan to include all the parts including a printed PCB to create an audio modulated flyback driver. I figure to start off with, since I have no clue what demand would be, I want to play it safe and only get enough parts for 10 - 25 quantity, which works out to be about $40, or about $4 a piece, not including custom PCBs. However, at >$2, the IRFP250 is not cheap even in 10's of quantities on Digikey. Looking to shave off pennies, I found the FDP33N25 for about half the cost of the classic IRFP250N and best part is that it appears to have simalar specs, and in some ways it looks like the FDP33N25 is even better! Bolded parameters are the (I think) prefered values. I do not know much about selecting the best transistor for the job, but I did compare the specs below: IRFP250N: 85mΩ Rds ON, 30A, 200Vds, 2800pf gate capacitance, TO-247, 0.65 *C/W FDP33N25: 94mΩ Rds ON, 33A, 250Vds, 2135pf gate capacitance, TO-220, 0.80 *C/W One thing I am concerned about power loss and therefore switching speed, so the MOSFET must be driven with a 15KHz to 40KHz square wave with very sharp rise and fall speeds. I was able to reduce power dissipation in my last circuit by simply shortening the wire carrying the signal to the gate, as well as adding a complementary pair of NPN and PNP transistors to the output of the 555 timer. That seemed to lower the drive impedance and switch the mosfet more rapidly, but considering that I still need to use active cooling and a brick sized heatsink, I think I can do better. Any suggestions?

Question by -max-    |  last reply


High Amp MOSFET pins?

I have bought two 75N06 MOSFET's rated a 75A that I am intending on using in an inverter circuit I will build the inverter will be powered with a 9v battery that will only trigger the MOSFET's that will lead to a modified microwave oven transformer and a car battery (65Amp). With the car battery I intend to draw about 200Amps from. At 50-60Hz the MOSFET's( I'm guessing) will be able to take that current but I am not sure if the pins will be able to handle that current the pins are only 0.34mm(0.01339Inches) by 0.6mm(0.0236Inches) thick so will it be able to handle 200Amps? If not could you suggest how to do this possibly with a few lesser current MOSFET's (lesser will equal a bit cheaper) in parallel? Thank you for any suggestions.

Question by The MadScientist    |  last reply


Help selecting a MOSFET, please

Guyfrom7up sent me this schematic for an ignition coil driver. I'm trying to determine if the MOSFET, IRFP450, could be substituted with any of the MOSFETs from Electronics Goldmine. The search doesn't create a link, search "mosfet" to get the list.I know I could get it from somewhere else, but EGM has parts for a few other projects, and I like to combine shipping.

Topic by CameronSS    |  last reply


HELP with P channel MOSFET.?

I've got a P MOSFET to connect some LEDs to 5v, regardless of where I connect the gate, the MOSFET (and the LEDs) always stay ON. Iv'e tried connecting the gate to 5 volts (on the source), to the drain, even to a higher voltage (13v) and nothing, current keeps passing through. I have checked my connections and pinout diagrams and they are all correct, but i thought that the MOSFET would let current pass when the gate was connected to Gnd and block it when it was connected to 5v (same as source), am I wrong? please help, i'm lost and i have found nothing useful on the web. PD i'm trying to control it with an arduino, and I have had no luck whatsoever.

Question by Emiliano Valencia    |  last reply



How many MOSFET's do I need? Answered

I am building a 2000W inverter powered by a car battery at 200A and I am unsure what to look at to find how many MOSFET's I need. Do I look at continuous current (in Amps) or power dissipation(in watts)? If it's power dissipation might you be able to suggest a MOSFET with a high power dissipation that is under a continuous current rating of 75A?

Question by The MadScientist    |  last reply


I need suggestions for higher power MOSFETs...

Hello! I'm, building a standard H-bridge motor control circuit, but I can't find the power MOSFETs I need. I have a schematic which uses IRF630 / IRF9630 MOSFETs, but they'll only handle 9 amps at 12 volts. The motor I'm controlling will require a continuous current of 25 amps at 24 volts, with a max of 45 amps (if the motor is in the locked rotor condition). I'd like them to reach "fully on/off" with +12 volts at the gate. Does anyone have suggestions? I'd prefer built in electrostatic discharge protection, but beggars can't be choosers, so I welcome any suggestions. Thanks to all!

Question by charlene.wintersrecos    |  last reply


Making a temporary amp with mosfet?

I don't know how to make a amp for my 4ohm 125watt subwoofer? I got heatsink and some Toshiba mosfets.

Question by ShaneR66  


How is a standard transistor different from a mosfet? Answered

So I have been teaching my self the basics of electronics and I find my self confused on the differences between a standard transistor and a mosfet.  I understand the physical differences but what I do not understand is the differences in their applications? A transistor is either ON or OFF which is controlled from the BASE and is normally OFF. A mosfet is either ON or OFF which is controlled from the GATE and depending on the type is normally ON or OFF. I think I might be over complicating things but based on my description of the two above. Am I missing anything important?

Question by atrumblood    |  last reply


Coilgun, Mosfet problem and joules?

I have two questions: when a mosfet is damaged, it conducts electricity without putting energy to the gate? I have the 75N75 mosfet and I want to use it on the rwilsford07 boost converter, but the mosfet didn't work and I don't know why it conducts energy without putting energy to the gate. I read that the mosfet can be damaged with static electricity, but I use always an anti-static wrap. The formula to get the joules from a coilgun is this?: 0.000005 * C * V * V C= uf V= voltage

Question by Kurt Gerhard    |  last reply


SSTC MOSFET over heating?

The following images shows my SSTC work, it is based on steve wards mini SSTC. But the problem is that the MOSFETs seem to heat up in like 3-4 sec of running. Input voltage is 220v AC(rectified and filtered later using a SMPS line filter).

Question by jasshopper    |  last reply


gate driver for power mosfet

I am strobing columns of LEDs at high currents very quickly (100mA for each LED, for 100us) with p-channel mosfets and LED drivers. The p-channel fets that can handle that sort of current (100mA * 24 LEDs) have gate capacitances of 1000pF and up. My microcontroller can't push too much current to the gate too quickly, which would result in the mosfet losing power to slow switch (and ghosting in the LEDs). I KNOW that some sort of gate driver buffer ic exists, i just can't seem to find one. Everything I am finding is for high-voltage or high-current applications and motor-driving. I just need something that will drive my gates at 200-400mA, and since i need 9 of them, i'd like them to be cheap. I dont need any of these motor-driver ICs or 3A gate driver chips... Can anyone help me out?

Topic by samurai1200  


Why use 2 mosfets? Answered

Http://electronicdesign.com/site-files/electronicdesign.com/files/archive/electronicdesign.com/content/14978/60488_fig_01.gif In the circuit, they use 2 mosfets namely q1 and q2. I was thinking what does q1 do. I tried simulating the circuit with and without q1 and the result were identical. Almost all synchronous rectifiers are following this pattern, what could be the purpose of q1? input and output conditions... Input: sine wave similar to AC mains (100Vrms 60Hz) Output: half wave rectified sinewave Load: 1kOhm resistor The red curve in the graph represents the voltage in the output The blue curve in the graph represents the voltage of a 1 ohm resistor in the input (for current reading purposes)

Question by codestroy7    |  last reply


What Do These Mean? Answered

I'm trying to construct an entry for the Wicked Lasers contest, however I keep on finding the same letters on several diagrams...  Can anyone tell me what the G, S and D stand for?

Question by thomas9666    |  last reply


How to use IRFZ44 as switch with pic micro? Answered

I want to drive stepper motor with pic 16f84. Can i switch on irfz44 with 5v signal from pic micro? Thanks.

Question by saikhamhein    |  last reply


How do I use MOSFET's for switching? Answered

I've been confused about this for a while now. I know how to use bipolar transistors(2N3904), but not MOSFET's. I've got one of these.

Question by geeklord    |  last reply


Did I just fry a MOSFET? Answered

So I am working on a project that involves electromagnets and I am going to control them through a Arduino with a MOSFET. However when I was testing a set-up using an LED I think I fried it. So I am going to link my Circuit layout (excuse the quality, I made it in MSpaint) rather than try to explain it in words. Also I am pretty sure my resistor was too small, but I don't know if that is the killer.

Question by Jayccob    |  last reply


Help selecting a n-channel mosfet and resister

Hey guys! Been a while. . . Anyways I was looking for some guidance on selecting an N-channel mosfet, and also what resistor to use when I'm applying voltage to the gate. So I'm working some long LED strips, and I need the mosfet to be able to handle at least 7 amps, so I was hoping for like a 10 amp mosfet or so. I just didn't want to guy buy the first mosfet I found on digikey, I was just hoping for some cheap good options or popular ones. I needs to be able to do PWM. Also I don't know where in the datasheets to find the information on what resistor to use on the gate. For instance I see people using anything from a 1K to a 5K resister with a TIP120. How do you select that information? I will be using an 5v output from my Arduino.  So after searching ebay I found the IRFZ44N mosfet, 55v and 49A. I know this is way over my needed specs but I can get 50 of them for 10 bucks. Steal. Since it's so overrated what problems might I run into if any? Thanks guys! What I've found so far: IRF740 - 400v 10A

Topic by HavocRC    |  last reply


Why are there only 3 pins on MOSFET transistors? Where is the ground for the GATE power? Answered

I'm trying to switch solenoids with the 5v output from a microcontroller using an N channel MOSFET transistor. I'm familiar with relays but not so much transistors, which is probably why I'm getting confused. From what I can determine, the DRAIN and SOURCE pins are like a normally open switch, and the GATE is the coil of sorts that closes the switch if it produces a nonzero voltage. If I hook up the DRAIN and SOURCE to a 24v power supply (the grnd to DRAIN and the SOURCE to the solenoid), and I have a 5v battery for the GATE....how does that physically attach to the GATE pin? Ultimately I'll use the output from the microcontroller, but in the meantime I'd like to do it manually. I realize I need a switch for the battery to toggle the GATE on and off, but if the +5v from the battery goes into GATE, where does the battery's ground go?

Question by uuuuuunnnnnn    |  last reply


How to switch 12VDC 1.5 amps and 0.3 amps

Hi :)I have to switch some fans on and off electrically but I don't really know how to do it.. I wanted to use MOSFET but is it a good idea ? If yes, which models ? I already worked with relays but it seems to be an "overkilled" solution for this application :p As writen in the title, one will be used with 1.5amps and the other with 0.3amps (12VDC both).Thanks :)

Question by QuentinP16  


Control of 25 electromagnets

Hello Everyone, I'm looking for a controller to manage 25 electromagnets. I've managed to come up with a driver circuit to energise each individual electromagnet using an N channel eMOSFET in parrallel with a diode. I need a programmable controller to operate the gate of each eMOSFET but the controller must be capable of managing all 25 switches. thanks for any suggestions in advance.

Question by wameri    |  last reply


can a jfet be placed in series with a mosfet's gate and swicthed on to turn off the mosfet?

Can a jfet be placed in series with a mosfet's gate and swicthed on to turn off the mosfet? i'd like to know if this is possible because the mosfet's gate senses voltage instead of currnet. I'm working on a schematic and its for a charge controller

Question by josh1001    |  last reply


Low power mosfet replacement problem

Can anyone help me identify a substitute for a mosfet? It is used, as far as I can tell, as a low power DC switch. It is a 6 legged SMD beastie, part number FDC654 - possibly with a P on the end and is completely short circuit. I'm assuming I've got the right device. There is some information about it here: http://www.fairchildsemi.com/pf/FD/FDC654P.html I can't find anywhere to buy this component as an amateur, and don't know enough to work out a suitable replacement. Can anyone help?

Question by throbscottle    |  last reply


Is it better to use a MOSFET with an Optocouple for PWM?

I want to control an LED strip from a microcontroller, ideally with parts I have on hand:- IRF740 MOSFET- PC123 Optocouple- ESP32 Microcontroller (Has 5V power regulator)- 12V LED strip (5m)A lot of the tutorials online seem to suggest that only a MOSFET are required (Except this one, which seems to me like a safer way of designing this, since I get to treat the 12V and 5V circuits as completely separate). I have a relatively limited knowledge of these things but it seems like sending the full current through the microcontroller on the ground side is a bad idea.Is it safe to run the LED strip's ground through the microcontroller? Are there any additional steps I should take to make sure I don't destroy my LEDs, MicroController, or anything else?

Question by jonrb  


How to test N channel mosfets? Answered

Hello, i built a ZVS driver about an year ago. I used to power it from a computer power supply at 12v ,than i changed the power supply to 30v and 10a.With the new power supply it worked as well for about 3 moths. A week ago a wire got burnt and a zenner diode. I wanted to test the mosfets too but he tests i searched on google didnt work. Please tell me a good method to see if my mosfets are burnt or not .

Question by theVader75    |  last reply


can i replace mosfet irfp250 with irfs630a ?

Can i replace mosfet irfp250 with irfs630a ? and what i can replace it with

Question by ouwelou    |  last reply


What if i use multiple mosfets in paralell??? Answered

Today my dad brought me another matshushita photocopier. it was a huge one with 10stage output. It got broken some years ago and stayed at my dad's work. When i dismantled it, it took me about 7hours. it had about 1000screws and lots of wire notches and zip ties. The gears and the motors were absolutely incredible. But when i went deeper i found a big 2200uf 400v Phillips capacitor. Needless to say that my coil gun will be very happy. When i went to the power the supply the pcb was broken. but however i found a bunch of irfp450 and 2 irfp050. they are in good conditions. And a 220uf 450v capacitor. i am wondering that if i put several irfp450 in a driver, will it increase its power output or something else will. happen. I am planning to make a driver which will drive my 1000W transformer. It will step up from 32v to 330(using it's secondary as output. I got it from another matsushita photocopier that my dad brought ten years ago) it will be used to charge my capacitors in no time. Here is a small diagram which will help. i'm doing this like so because i don't have enough money to invest in home projects.

Question by ARJOON    |  last reply


Can I replace the transistors in this LM723 regulator circuit with MOSFETs? Answered

I am trying to build a power supply capable of outputting up to 15V at 10A. The heatsinks I have are not suitable to use with the 2n3005s TO-204 case. Also I can get IRFP250 MOSFETs a lot cheaper. The transistors I want to replace are Q2-Q4, Q5 I will not include because I only want 3 FETs because I only want a 10A supply not a 20A.  Here's the link: http://www.thebackshed.com/forum/forum_posts.asp?TID=2249&PN;=2&TPN;=1http://www.thebackshed.com/forum/forum_posts.asp?TID=2249&PN;=2&TPN;=1

Question by The MadScientist    |  last reply


SMPS failure, the Gates of the MOSFETs exploded?????? Answered

I've just build an SMPS using a TL494 chip using the power circuit from this circuit from uzzors2k, it's just a standard half bridge in my case using IRFP460's. The MOSFETs are driven through a small transformer that itself is driven with a H-bridge.  Yesterday I was trying it's first mains power test slowly ramping up the voltage with a variac when at about 180VAC i could hear some fizzling from the circuit and at 200V the GATE's of the MOSFET's exploded violently, at close inspection there was no shorts or flashovers and the gates were the only thing that was damaged at all. One thing i noticed later was the output waveform of the power transformer, unlike the signal waveform it didnt exhibit the same 96% duty cycle but a 100% with a lot of ringing on the rising peaks of the square wave, i know this can probably be fixed by reducing the duty cycle but i cant see how it could've blew up the gates. I've included some pictures so you can see what i mean by explode, as you can see on the left Fet the gate pin has completely blown off and the copper has melted slightly and the right image the same happened but i cracked the Fet open with a hammer to see if there were any clues inside. I really dont have a clue why this happened and would appreciate some help, thanks in advance.

Question by The MadScientist    |  last reply


P-Channel MOSFET woes - anyone know how to drive one of these things with Arduino?

Hi all, I’m a hobbyist trying to build a digital controller / power monitor for a green power generator project built from an auto alternator. Hoping to use an arduino microprocessor & some simple transistor circuits to power an alternator’s field coil which at 13v can draw up to 10amps of power. From what I’ve read I think I need high side PWM switching because the alternator shares a common ground with its other electrical connections preventing me from using my usual novice NPN based bag-of-tricks. From my reading I assume some sort of PNP or P-Channel MOSFET is in order (components I sadly have no prior experience with). Alternativly I've read about using fancy high side controller ICs to drive regular NPNs but don't want to go that route. So far everything seems to work except I clearly can’t figure this P-channel MOSFET out (IRF6540)!  No matter what I try I always get a high voltage at the drain pin (full-on condition) regardless of what I do to the gate pin. I uploaded a portion of my schematic as a test circuit I think should work from my limited understanding and online tutorials: http://www.curtismasonjohnson.com/sandbox/ProblemCircuit.JPG   - The NPN driver in the drawing (2N3904) by itself works when tested with a voltmeter and toggling the input   - If I replace the p-channel mosfet with a PNP transistor it work as expected. Shouldn’t this mosfet work pretty much the same? My puny TIP127 PNP can't handle the current if I were to hook up the load.   - I’ve tried several IRF6540 components   - I’ve tried connecting the MOSFET’s ground pin via a current limiting resistor directly to ground. Also via the resistor to 13v. No voltage change on the drain pin in either case. Clearly I’m missing something embarrassing and fundamental. I mentioned I’m a hobbiest, right - my day job is managing global marketing programs for fortune 500s and don't know anyone that knows anything about electronics! After years of electronics & robotics projects I’ve yet to be stumped to the point of needing help til now - amazing how much you can self-teach via google and such. This one has me beat – hope someone can help as I have no idea what to do next! Truely appreciated...

Question by cmjstealth    |  last reply


How to protect OpAmp output?

Hi, I have an OpAmp which controlls the Gate of a MOSFET. When the MOSFET dies, sometimes the voltage it's running on (50V) somehow gets to stand over the OpAmp's output which destroys it. What's the best way to protect the OpAmp from the high voltages that get to stand over the output? Will a zener do the trick? Trigger transformer won't be easy to use here because It's a PWM controller so I need nice block waves. Diode on the output? but won't this be bad for delivering good current to the Gate? ... Any ideas?

Question by DELETED_Electorials    |  last reply


Delay off Circuit 12V - 3A? Mosfet or Relay?

Hi all, I want to make a delay off circuit 12V - 3A. When the switch is ON, the circuit will operate during 1 to 3 minutes, and when the switch is OFF, the circuit should work during 0.5 second before it turns off. I made a delay off circuit using NE555 and a mechanical relay and it works. However, I need to make a smaller, cheaper and more efficient circuit. I need your help and your advice to gain knowledge and improve my circuit. Thank you.

Question by plantin110    |  last reply


how to avoid using a jfet buffer?

I am trying to build an overdrive circuit, and it requires a jfet buffer, which i do not have, nor does radioshack (to the best of my knowledge), i do however have multiple mosfet buffers.  could i use these in place of the jfet, and if not, is there a way to remove the buffer altogether.  the scehmatic and diagram are here, i am trying to build the big daddy. thanks in advance!

Question by fatfoohy    |  last reply