Wish you were my tutor in school, you make things so easy to understand, thankyou

@justintime808

5 жыл бұрын

seriously though!

Nice video. I spent the whole day today desoldering components from an old stereo and a satellite decoder, then checking them out with my microscope to get the numbers, then looking them up on the web to look at data sheets. Found lots of things I never heard of before, and a few things I am having trouble finding on the web. Jfets are new to me too, but my old head hurts after all of todays shenanigans, reading, and burning of digits, lol. I think this is yet another one of your videos that will be marked in my playlist for repeated study. Thank you for sharing your knowledge Brother. It sure makes things easier for folks like me to progress in this great hobby. Love from UK, Ken.

I found your channel a few months ago when I was watching reviews for the ZENY 937D+ soldering station (which I ended up buying) and have been a subscriber ever since! Love your easy going, easy-to-understand videos about so many electronic components I "sorta" understood before... you've clarified a lot of my electronics misunderstandings and misconceptions! Love your videos, keep up the good work!

Thanks for the demo! Much appreciated

I really enjoy your videos and am learning a lot from them. Thank you!

Great job, thanks Paul.....and left with a smile. Cheers mate!

Hey there! Thanks so much for the video! I have a final tomorrow and this was part of our study guide! I am most nervous about the JFETs / Transistors part... So your explanation and fun video made study time much easier! Have a great day!

Geeze makes me glad I don't do any audio stuff. Never seen anything on JFETs before, but your explanation was superlative. Even an old duffer like could understand. Thanks for another great video!

@learnelectronics

5 жыл бұрын

Thank you my friend.

@HazeAnderson

5 жыл бұрын

I am learning EE by doing audio stuffs! HALP!! 😂

Thanks for creating these amazing videos! You have a tremendous talent. 👍👍

Cool jfet explanation you helped me understand something that always bothered me about jfet’s. Thanks Paul great as always.

JFETs are something ive never used, it's always been BJTs and MOSFETs. Big thanks for the explanation Paul. Take care mate and all the best to you and your family.

Sadly, posting something stupid seems to be business as usual on the YT comment section. Thanks for the video, it really helped me understand FET's.

@chrismason1530

3 жыл бұрын

Welcome to Planet Earth

For any readers coming to this, what might have interrupted the normally on state is to think about a bias resistor on a vacuum tube, the bias resistance auto holds the Grid low by having a potential at the Kathode This is what is likely occurring in the video, if the R was moved to the Drain section i think you would observe a normally on state at 0 Vg Thanks for sharing great video.

Excellent video. Mind coach. I experience this video as if my hands are actually doing it. That's the best way to learn practical. Besides, you can't help but like this guy. The more I listen to him , the more I like him. Those hands, have a very nice person to serve.

Just a bit to add about CHF - Mom suffers from it, she has also had 3 heart attacks in the past 2 years. She has just gone through and survived COVID and is in a nursing home, however that isn't bad since she is 95, nearly 96 years old now, is still walking the halls of the home and now that the COVID is over, she is sharp as a tack mentally (she did get a bit confused during the infection.)

Great introductory tutorial

JFETs seem to be very popular as the first amplifier transistor in a radio receiver. One note on static sensitivity, most digital ICs have some protection diodes etc. built in, making them much less likely to get destroyed by the low levels of static in normal handling. But these individual components, like single mosfets, do not have any protection built in and are much easier to damage.

I had an issue with a FET. It was used as a switch, but did not work. I removed it, tested it on a component tester, checked as working. Double checked with the diode function of my DMM, tested okay. Installed a new FET, circuit was now functional. Perhaps I need a class on testing FETs. Good video, Thanks Paul.

Thanks Paul.

very good jfet tutorial. thanks for sharing your knowledge..

N channel depletion type JFETS are normally on devices, which means that with no voltage applied to the gate, current will flow from drain to source. To turn off a JFET, a negative voltage with respect to source must be applied. Positive voltage should never be applied to the gate of a depletion JFET.

Thanks for explanation

I appreciate your video.

Really good thanks

This makes them more understandable. I've been doing some research and I have read that the JFET will act more like a "tube" in a preamp circuit that a regular transistor like the 2n2222. I'd love to see a preamp demonstration/circuit for the audio preamp. As a guitarist, it would come in handy to understand how the preamp works including a comparison between the different transistors. Thanks, Paul!! Another great video!!

@learnelectronics

5 жыл бұрын

Dave, audio is just not in wheelhouse. I wouldn't be confident I could teach it. Sorry to let you down.

@davidglynnguitars8119

5 жыл бұрын

@@learnelectronics no worries. I just want to learn what I can and your videos always point in a good direction.

The depletion mode JFET makes a very simple constant current source. Ground the gate and connect a resistor between source and ground, this defines the drain current. I used one in a wide voltage input range probe. Their electrostatic sensitivity makes them fun to play with, emulating the response of a gold leaf electroscope. You can do the tricks with static charged plastic rulers and balloons. It is the possible to detect the different polarity of the static charge on plastic and glass rods by inducing a charge on the gate by capacitive coupling. The one you are using looks similar to the bilateral switch, often used to route and switch audio signals. The IC equivalent might be the quad CMOS bilateral switch, the CD4066 or the even more useful HEF 4053B. To digress a little, the 4053 is a triple, single pole, double throw, bilateral switch, ideal for switching audio signals, since it allows the signal path to be switched from through to ground, greatly reducing noise pick-up in the off state. Using jfets as audio switches is complicated by the fact that they are not truly symetrical, as the gate control signal is also referenced to the audio signal path.

@peterfitzpatrick7032

4 жыл бұрын

I always love educated comments... sometimes they can be as educational as the vid ! As yours is .. 😎👍☘🍺

Nice video and subject.

gate to source/drain is a diode, must be reverse biased to have high resistance input. Cannot be turned on, only off (reverse of BJT). Drain and source can be interchanged on symmetrical devices (gate junction in center of channel), but these have less gain than asymmetrical device with gate junction closer to source.

PAUL, make a lesson about SiC Silicon Carbide Transistors theory like Drift Layer, Dielectric breakdown field strength, electron saturation velocity, energy band cap, thermal conductivity because these parameters you have to know about when dealing with SiC which are replacing high power transistors.

Hey Paul, I’ve said it before but your explanations are the best. You’re my go-to source for anything electronics so I’ve finally signed up to you patreon. I’ve been playing with JFETs as voltage controlled resistor to control the tuning of an oscillator which is working out well. Have you ever played with the LM13700 OTA? I’m having a lot of trouble understanding it but it sounds really useful for CV. If you’re looking for content suggestions it would be great to get your take on it. Thanks again for all the great content.

@HazeAnderson

5 жыл бұрын

I issued a save file on the Data Sheet only to realize I had already downloaded this data sheet. I am not sure where I saw it being used but the LM13700 looks like a KILLER audio applications chip. Cheers!

@andyhubbard7374

5 жыл бұрын

@@HazeAnderson This is well worth a read bit.ly/2WMaUMk. It's got me close to understanding it but I'm still struggling to see how to control and test the linearizing diodes.

@learnelectronics

5 жыл бұрын

I will check it out

@SkullDraizer

5 жыл бұрын

Just want to second the idea on a video about transconductance amps. I just got a tube of 3080s in the mail and plan to make some synth diy stuff with them. @learnelectronics keep making great videos!

@pepe6666

5 жыл бұрын

i didnt understand transistors for most of my life until a while back i realised that they are a controllable resistor. everyone always talked about them controlling big circuits and amplifiers and gate source drain collector emitter voltage and stuff and i didn't understand. then someone was like 'its a resistor that you can control' and im like. oh. oh yeah. now it makes sense

Thanks, that video helped.

Useful little video. I never built anything with a JFET in it. Just out of curiosity I read a little.

Thanks for the video. I think biasing the 2N5457 with positive voltage to the gate is a little bit confusing and does not make any sense. The gate of the N-JFET (like 2N5457) should be reversed biased - with negative voltage. This is how you control current to flow. Your FET is opened all the time and your circuit just passing current to the led because of voltage drop.

Sir you explain very good. Can you please demonstrate how "Uni Junction Transistors" work, there's not a single vedio out there to explain it practically.

Grate video 👍🏻❤️

Thanks for the video but I found nothing different between jfet and bjt in your demo. Bjt will also doing the same effect by touching its base terminal.

thx Paul

Nice!

I'm very new into electronics ( only have the official Arduino kit and making the love meter out of the electronics book ) but find this very interesting and way above my current pay grade. I really enjoy this channel though. Where do you buy your bread boards from? I'm trying to find ones that don't have as much play or are as loose as what I currently have.

@KissAnalog

5 жыл бұрын

Zombie Dave look for Elenco on Amazon, they make a good quality product. Use one of Paul’s links to Amazon, so then it doesn’t matter what you purchase - he will get a credit.

@learnelectronics

5 жыл бұрын

Check my Amazon store

@ratrod67

5 жыл бұрын

@@KissAnalog Thank you!

Are they sensitive enough to work on the current available in the atmosphere during normal conditions?

actually the drain and source have equal doping concentration here..not unequal like that of collector and emitter of BJTs...that's why they are interchangeable

You missed a bit in your explanation. There are two types of FETS: Enhancement: Need a positive voltage on gate to turn on (For N-channel). Depletion: Is one at zero volt on gate (For N-channel). MOS FET exist in both types, with JFET you have to use depletion due to the diode in the gate. Tying the gate to the source will make the FET into a constant current source, when the source is negative. This is because the gate will be negative due to the internal voltage drop in the transistor, and this will make the FET start to turn off. Depending on the parameter of the FET a resistor may be needed between source and gate, current is drawn from the gate connection (i.e. gate is minus and drain is +).

I don't get it. Everytime I try to order a popular part like the 2N5457 or a MP102 I find out they're discontinued.

Dude I have been trying to wrap my head around these things ... I have several circuits ahead of me that require JFETs and I do not understand why ... probably something about "high impedance" ... that's my brain on the floor by the way ... it falls out sometimes 😂

I make 9 volt ghost detectors using JFET's with an LED resistor and battery clip. Simple and the ghost buster group I make them from say they are very effective. I am not into ghosts but love playing with electronics.

Ok. I have a CDM324 module. The output from this device is faint, millivolts faint. I'm thinking JFET to develop a usable signal.

To make jfet devices work at higher voltages , the source and drain could have different doping profiles, then you can not switch source and drain. But for regular jfet, for example the one you are using, you should be able to switch source and drain because the doping profile of source and drain is the same. Funny, that you found even this transistor you can not switch source and Drain!

Hi, you mentioned that the JFET would stay in the on state until a negative voltage was applied, but it didn't seem to. When you removed the gate voltage the LED went out. Did I misunderstand?

@kolinevans9127

3 жыл бұрын

The resistance was acting to bias the gate just as in the function on a vacuum tube bias resistor. Move the load to Drain input section it would have I strongly believe.

I know how to apply current, you flip a switch and you send current to no matter what is on the other end. Now but how do you apply voltage to whatever it is on the other end?

@alchemy1

3 жыл бұрын

@@lepidoptera9337 What a cop out. Just say you don't know.

in JFETs drain ans source are always interchangeable because they are symmetric

@kolinevans9127

3 жыл бұрын

Makes sense, basically a solid state vacuum tube.

Hai i am jayasurya ,please send the video for mosfet with real time application

By the way, this is the FIRST video that I have seen (I am sure there are others out there) that shows the LATCHING behavior of JFETs ... holy cow that was so simple. Why people gotta make this harder than it already is? Oh right ... job securities. 😏

Where do you put your camera when recording? Maybe a video about it?

@learnelectronics

5 жыл бұрын

It's on a flexible boom

@KennethNicholson1972

5 жыл бұрын

With his advanced knowledge base of components and their functions, I am guessing he is an Alien, or a Human from the future, so it is likely he has multiple spare arms to assist him in his work. lol.

@efesstuff4936

5 жыл бұрын

Thanks. Hahaha maybe true =)

"Whats happening?" - you mean everywhere?!!! 🤔😮🤣

How do you know which one you have? Jfet, mosfet, BJT? I'm trying to fix a printer that was reverse polarity. So I had one blow. But it is pre-standard component. So the numbers won't cross reference. And some printers have the m735 and some had sms 445.

@clydecare

3 жыл бұрын

@@lepidoptera9337 pre standard means before the numbers were required to be standardized for products sold in America. Before that the companies put a part number rather than a reference number for value. So before 2002? You had to look it up in the specific companies book to find out any info.

@clydecare

3 жыл бұрын

@@lepidoptera9337 I know many businesses like Apple don't want people to fix the products they make. But there is a standardized code on most electronic components. But micro components don't have the space. Which is something we are dealing with in the right to repair laws that are being heard in many states in United States, that would require transparency and the ability to have a diagram that can be referenced to find the values of components.

@clydecare

3 жыл бұрын

@@lepidoptera9337 well I'm so proud of you for thinking you know everything. But the chides on resistors didn't need to reflect value. Till around 2002 Federal Regulations required all manufacturers to put regulated codes that would apply no matter the manufacturer. And I know this because I work on old printers designed in 1998- 2003. Many of the components have a company logo then a company part number with no numbers reflecting values. No data sheets for these components at all. You have to fugue it the company and find the old books then hope the component is in the book to even get the value. Smd company part numbers are on them. Not value. Today if I go buy a small resistor it has a value code on it. That is Federally Regulated. But companies have found loop holes. And we can't as a country continue to trash Everything that breaks. We will run out of places to bury them.

@clydecare

3 жыл бұрын

@@lepidoptera9337 and SMD resistors? Micro Components? how do you Identify them? because thats what im talking about. everything has an identifying number on it. i have pre standardized smd resistors. the numbers dont give the value. they are a part number. my uncles business manufactured a smoke opacity meter to test Big Rigs and off road diesel Equipment. the last motherboards were made in 2002. i still repair them and the seiko printers that they stopped producing in 2003. the designer took all info on the meters when he left. and so here we are. with me asking a question about components that have no identifying numbers. that blew. arguing with someone who clearly doesnt know or remember the change or installed Regulation. it literally took 2 years to get an answer. granted i only asked maybe 25 times in different groups. but one person finally gave the answer i was looking for on a FB group. they have been doing this 40 plus years. and sent me in the right direction and even emailed company logo images that they compiled in the years they put together to help people. and micrichip technologies doesnt respond to inquiries about outdated, pre-Regulation components. so even the manufacturer of the components employees couldnt answer my question on value, because the numbers dont reflect anything in the system. that dates all the way back to the regulation put on manufacturers in the united states. this isnt your problem. and the answer is over your head

@clydecare

3 жыл бұрын

@@lepidoptera9337 whatever you say. The part i was looking for was a regulator. But every single ejecting ship i bright it to thought it was npn. Including the manufacturer

im working on a Yamaha A520 amplifier. so get in here

Interesting

hi .. I wont to ask you what is going on to robot arm I know it has been a long time but I'm actually interested and starting hacking my robot arm within transistors but its not working as I accepted any way I found Adapter for joining Potentiometers in thingiverse and I hope you start working in that project again

@learnelectronics

5 жыл бұрын

Project was abandoned

Like it

Static sensitive... hm... according to my personal experience , I handled with "Static sensitive devices" every day in past 30 years, and I NEVER damaged single component , I forgot to say that I never care about handling with those components, without any grounding bracelet or any care. In other hand, I destroyed most of component purposely, very rarely by accident.

@africanelectron751

3 жыл бұрын

Haha I agree with you, but when you are handling a $10k fpga you do it because you want to be able to tell the boss you did it.

Sir .may i know the testing method of good or bad jfet using diode mode tnx

Bidirectional transistors! Who'd a thunk! 😋 Interesting. Should be very sensitive!

@learnelectronics

5 жыл бұрын

Weird eh?

@YouAllKnowBob

5 жыл бұрын

I guess it makes sense if they can maintain tolerances and put the gate material exactly in the center. The core is a single piece of n material so it wouldn't matter which direction the current flows.🤔

Hi. i have a usb microphone and it has a 2sk660 jfet connected to the capsule. I want to replace that jfet to reduce noise for my mic. I founda adviceon frome homerecording forum 10 years ago. to replace that jfet with 2n5458 and i need to bias the FET, but unfortunately I don't understand what I have to do. can you help me? Here is what i found: " As for this mic, the capsule isn't bad, you can improve SNR by replacing that FET with any of the usual lower noise suspiciousness (even 2N5457 works fine). 2SK596 is very noisy by comparison. You will also need a high-value resistor (at least 100M) to bias the FET The easiest method is to ground, and given the limited supply of 5V that works fine here , you should have a resistor (not a critical value; 3K3 to 10K will work) from the source to ground. This will reduce distortion/increase max SPL handling."

@tonyfremont

Жыл бұрын

This is late, but I believe that means to put a 100M resistor from gate to ground (Vss).

Did I fail to pay attention somewhere? I have never used JFETs, thus they are completely new to me. From this I got the "feeling" that a JFET is a MOSFET with a bad datasheet. I must be missing something :-) (Just realized that above might be seen as a negative comment, It's not meant that way)

@SurajGrewal

5 жыл бұрын

It's Leakey but blocks current in both directions Mosfet allows it in a direction, due to inbuilt diode

@rolandberendonck3900

5 жыл бұрын

Did you already mod your clamp meter? I just got the eprom programmer in my mailbox.

@flemming2jacobsen911

5 жыл бұрын

@@SurajGrewal Ah! Good point. Thanks.

@flemming2jacobsen911

5 жыл бұрын

@@rolandberendonck3900 I was not aware that it was now possible. EDIT: Stuff ordered. Thanks for the hint. EDIT2: To people wondering what we are talking about: kzread.info/dash/bejne/mIxhqMqqabWapbw.html

@rolandberendonck3900

5 жыл бұрын

@@flemming2jacobsen911 Yes it is. I replied you in that topic, but it seems like you missed it. Take a look at this video: kzread.info/dash/bejne/mIxhqMqqabWapbw.html

It might be me, but this video actually seemed a bit messy. Sorry. I see all your videos. And I thought the led should turn off only when it had reverse polarity.

This is a bit confusing to me. In the video it is claimed that he uses an N-Channel depletion mode JFET, so shouldn't the LED light up when the gate is at 0 volts? I think it's the wrong part. That thing behaves like a MOSFET.

@raviduprasanna6401

2 жыл бұрын

no it should light up when there is no voltage in gate to source when apply voltage -volt for gate and +ground , stop drain to source current flow jfet behave opposite as mosfet transistor and gate voltage also invert as N-mosfet

@1900OP

2 жыл бұрын

@@raviduprasanna6401 did you even look at the video?

Can you do a BC547 and compare to J201 please?

@RobertLongM

3 жыл бұрын

@@lepidoptera9337 Because I don't know anything about the difference... I'm new to playing with an LM386, but so many other similar looking components... Are both called Transistors? Do both attempt to do the same?

@RobertLongM

3 жыл бұрын

@@lepidoptera9337 I started with making a simple LM386 amp. Then wanted to build it into a guitar sustain pickup that vibrates the strings... where the OUT is the new 8Ohm wound pickup to vibrate strings... But some circuits were transistor, some not... and I think there is more science to it than I believe

@RobertLongM

3 жыл бұрын

@@lepidoptera9337 thank you btw!

117k Subs And 117 Comments. God Pointed Me Hear To Lear A Lesson. 🙏 👍

So, where were the JFETs? Under something or in the bin? 😁

@learnelectronics

5 жыл бұрын

Never found them. These are new.

@Helmut314

5 жыл бұрын

Oh, they will turn up as soon as you dont need them. Its the way of things™

guys im about to fail my class bc of this shit, can someone help ajdhlihísderf

First one