i agree completely. people have gotten lazy when it comes to learning

Been following you and Fran for a long time now.... nice shout-out :)

Really good practical explanation for a very important issue to anyone who is interested in the design phase "the Miller effect input capacitance and output capacitance and their effects on choosing the surrounding components." really good video.

You would probably get different oscilloscope traces for different transistors of the same type (especially the cheaper ones) because they have different current gains. If I was going to use a different type of transistor (beats ordering an expensive replacement) then I would probably change the biasing to suit. I have always thought that it was a poor design practice to make a circuit critically dependent on the type of transistor used though this may be a deliberate choice by the manufacturer.

adding a small resistor to the emitter would improve the bottom end clipping.

Hi! Glad to hear your son plans to study electrical engineering, I've been doing that for over a year and, while it being a challenging field filled with math, math and even more math, it never ceases to amaze me. Thanks for your knowledge and your teaching. Finally, one viewer request : please go in a deeper explanation of oscillator circuits and of how am/fm receivers work. There's a lot of videos showing how to calibrate and adjust radios, but how they work isn't that clear to me.

Very nice presentation... and a lot of self awareness shown. Good job.

Fascinating video...cheers!

Ooooh! Russian transistors! I don't know why but there's something about Russian components! Especially if it's cold war era stuff! My favourite amplifier is using TO66 metal encapsulated transistors for it's output stage and I believe the input was using TO92? I could be wrong on that one, it is a germanium transistor, when I got the amplifier, someone had just clipped the legs on the failed TO92 and just soldered the new plastic package transistor to what was left! Talk about being lazy! There was something about the sound of that amplifier which I have never heard before! Hand built by someone lovingly at home back in 1973 and apart from the failed small signal transistor, everything else was original, still has it's original Elna capacitors! It gets used daily even if I'm not listening to it, electronic equipment that gets used a lot will outlast something that only gets used every once in a while... Strangely enough, I have been expecting my Samsung TV to fail! It's a plasma which I have had for at least more than 10 year's now, I have seen newer TV's out on the nature strip! But this TV has this thing where it turns itself on without lighting up the screen, it's some kind of feature that gets rid of screen burn in, remember when that was a thing lol, well it does work but I have been thinking that there's also a side effect that Samsung probably wasn't aware of at the time, by having the TV fire up every single day and it does regardless of use, it's actually keeping the capacitors in good condition! I reckon that if I unplugged it for a few months and then fired it up, I will get at least one exploded capacitor! If not more, they really don't like coming out of a coma at full rated voltage! If you have a Variac and bring it up slowly over time, you can save it! Leaky capacitors are a different thing, those things should be replaced regardless...

@knifeswitch5973

3 жыл бұрын

Shango066 does the USSR stuff quite a bit. Give his channel a look. Some of those soviet radios are built! Entertaining he’s always digging in bags and bags of Soviet transistors and tubes

Excellent explanation!

Waaauw this is what you would call a fresh video... 23dec on the scope at 9:30... this 17:30 my time cheers and merry christmas... have a great 2021

I bought some bread board this year. Been meaning to do some sort of experiments like this. Part of my bid to move up from a "screw driver man"

I love these "random vids". I'm sure your son will do well and have fun in college. Your son will have a "strategic advantage" since he has access to his Dad's (uber-cool) test lab. (EE was my original major until I discovered "computers" before they got small...). I would love to see a test like this done with various power MOSFET's used for audio amps. (scaled for higher power output of course..)

great video. thanks for doing this comparison. We radio guys would love to see you do this with an RF front end amplifier circuit, as they are a source of great debate when it comes to transistor substitution. maybe a common base configuration as a platform. One note is that NTE is a known parts re-labeler and the NTE107 you have there might not be the same NTE107 that i would get if i ordered one. for us in the RF realm, it's all about noise floor, and the great debate is all about subbing out a 2SC1674 for a 2SC2999. then there are those of us who wish someone would design a dual gate mosfet front end LOL. another interesting video idea would be to show how the peripheral components change the characteristics of the circuit more so than just plugging in a transistor with a higher beta spec. always enjoy your videos and especially the real world explanations.

Those plug-in breadboards are ok for low frequency but the strips underneath are capacitors

Surely the load beyond C4 (where TP2 would be) would also play a part for impedance for the PNP?

Hi, and thanks for this comparison video. It would be interesting to see if the difference between the transistors would reduce if you added a emitter resistor.

Shango066 just posted a video on a Russian transistor am radio with a bad mp40 germanium transistor. Funny how these things always come up at the same time...

@1959Berre

3 жыл бұрын

Indeed, Shango mentioned he had never seen a bad Russian germanium behave like it did. (And I trust he has seen a ton of them). So, that is a wonderful coincidence.

@zulumax1

3 жыл бұрын

@@1959Berre Shango066 is great entertainment as well as learning a thing here and there. I was waiting for that transformer to start smoking. 150ma DC running through it, wow!

These days I want to know so many things, across so many fields, that the Google shortcut has been invaluable to me. You probably can't internalize something and make it part of your working knowledge without some experience, though. What is most fun, of course, is to google for the answer to a known question and then use the knowledge to advance to a previously unknown solution. Shoulders, not toes.

Thanks, Tony! Your videos are always entertaining and informative.

It would be interesting to see the thermal effects on the circuit. I bet even the warmth of your finger will change the waveform. Without an emitter resistor the circuit will be very sensitive to the transistor beta and the bias will be sensitive to vt which is influenced by temperature.

@cjay2

3 жыл бұрын

Exactly, without the emitter resistor to lift the circuit into the linear region, the beta basically controls the result. I'm not counting the thermal effects.

Seems important.

Interesting video! Things can blow up on the bench, not on paper.

Merry Christmas to you and your family, Tony, and also to Bella. I'm glad you mentioned the miller capacitance (parasitic capacitance). It would be a rather long video to clear that out. Maybe a next time, when you can spare the time? BTW, you don't have to be a critical listener to hear the obvious distortion when it reaches a critical level. The distortion(s) you show here are pretty severe.

Now, what if you did the same w/ tubes?

@zulumax1

3 жыл бұрын

I was just thinking, so now we are going to be rolling transistors, like people roll tubes? Mullard vs. Amperex

Nice video, RF and OSC can be compicated in a circuit

great info man and Merry Christmas!

HIIIiiiiiiiii, IT'S FRAnnnnnnnnnnnnnn.... Just started watching her a month ago. Good stuff.

@mmaranta785

3 жыл бұрын

Fran is a very knowledgeable guy concerning electronics

Excellent! Love it

more info to add to the knowledge base for when im pondering how a circuit works and what can affect it...,, thanks Tony.. awesome vid and content,,Merry Christmas to you and yours..

Presumably the measured frequency changes because the transistors have different Cib or Cob and this changes the 1/2 pi L C resonant frequency?

Merry and joyous Christmas Tony, family and friends. And a healthy and prosperous new year.

To make the comparison more similar wouldn't just reversing the supply voltage for the PNP transistor? That way the DC biasing and the AC coupling would be the same as the NPN.

@blacksmock445

3 жыл бұрын

I didn't see what values R1 & R2 were. R1 would be much larger than R2 for biassing a silicon npn transistor without an emitter resistor, so merely swapping the collector and emitter would put a large voltage between the base and emitter of the germanium pnp transistor, perhaps as much as 11 volts. Perhaps the Soviet era components were bomb-proof.

Never click on a nice girls comment . You go down a diffrent rabbit hole. Great video as always, hope your son does well. Merry Christmas.

Nice and Interesting video! Merry Christmas!

Emitter resistor may help in your waveform

@johnnytoobad7785

3 жыл бұрын

I've never used the BC5xx series or the 2N55xx series without one ! (Re) Those are my two favorites in the line-up..at least for audio.

@1959Berre

3 жыл бұрын

That is correct, obviously. But the aim of this video is to show the different behavior of the transistors under equal circumstances. The emitter resistor would prevent the effects of oscillation to occur.

@zulumax1

3 жыл бұрын

@@1959Berre Good point

Nice video.

To my non-electrical engineering eye, it looked like the transistors where the bottom of the waveform had a wider flat spot oscillated at lower frequencies. More time was taken up recovering from the clipping at the bottom which lowered the frequency. Am I correct on that?

Odd how so many transistors in vintage stereo gear are obsolete. Both my Pioneer and Sansui QR4500 have many obsolete transistors.

Hi, How are you getting your scope on the PC?

Informative.

Transistors behave differently in higher frequency circuits.. I think the Ge one must have been a "high frequency" device, not of the more LF types. Merry Christmas, Happy 2021 to you and family, Tony!

Thanks for the video, Tony. I really like you YT content. Very informative and educational. I know I'm nitpicking here, but at kzread.info/dash/bejne/n61qo62oaNm8XbA.html you said "20 Mhz" when the the frequency was really something like 20 kHz lower.

Hi Tony, can I ask what is L2 doing?... understand the simple tank circuit with a tap in, but why the second coil. it's no choke, it's really bugging me🤔 (Pun intended)

@airmann90

3 жыл бұрын

I'm pretty sure that's there to keep rf out of the positive supply. Should act as a short to the 12v supply and a block to anything high frequency

@cjay2

3 жыл бұрын

L2 is the collector load at RF. It's pretty much a short circuit at DC (probably ~ 100 ohms), but at the operating frequency it has a reactance of 2PiFL = 6280 ohms. The circuit's output voltage at operating frequency is developed across it. Without an emitter resistor, this circuit, as drawn, operates in the non-linear region of the transistor, which is generally not optimum.

@mattlambert7221

3 жыл бұрын

@@cjay2 makes sense if the inductor has been 'tuned' for that frequency, so it acts as a choke (>f=> reluctance) but similar could be achieved with a resistor? Looking closer at his diagram, there is a link back to the base, which may be there to provide feedback /osc stability? That would help to keep the transistor from saturation...

Analog, especially RF/HF are witchcraft! When dead shorts start to act like antennas and filters, im out :P - 73 OM!