Power Supplies to Audio Amplifiers.
Added 2017-02-11 13:00:56 +0000 UTCAnd all the signals in between.
Patreon NEW LIST of Videos: https://www.patreon.com/posts/8239565
Comments
as I move along it would be nice if you displayed the video/course number with title of video.
Nicholas Nanosun
2025-12-29 23:14:25 +0000 UTCThis may be the wrong video, but why does the signal on the vibrator not go from 1 to 0 in one line, why is there a deadzone where it's like half the voltage - or am I misinterpreting the oscilloscope picture?
Linda Juffermans
2025-12-17 12:19:20 +0000 UTCNot the expert here but I found it gets easier with repetition, trial and error. (Like almost all technical stuff.)
Richard
2023-09-19 16:56:58 +0000 UTCHi, just started the whole class. What I think is missing from everything I seen everywhere is how to really read schematics. I don't mean symbols. What I mean is how to actually follow signal path ot voltage distribution. Because all manufactures do it different, from black dots, to just dots, single lines, boxes, fat lines or skinny ones arrows etc. I find that I spend lots of time trying to follow the path. But regardless great videos and teaching.
Rey
2023-08-08 05:51:47 +0000 UTCThank you for this as you explained how a vacuum tube works perfectly and how the phase inverter works. You showed amplification from the input of the signal generator through half of the first tube and measured it showing 344 milli volts to 24 volts. Then you showed us an 11 watt output from the final to the resistors replacing the speaker. Excellent:-)
Bruce Claxton
2023-06-16 02:31:08 +0000 UTCWhat oscilloscope specifications would you recommend for HF amateur radio use?
Howard O'Chocke
2023-05-01 23:31:10 +0000 UTCWorks fine here 2
Paul Stringer
2022-12-08 03:42:37 +0000 UTCGreat Info. Thank you Mr. Carlson
LoSaYa
2022-10-19 19:42:55 +0000 UTCPerfect. Thank you Paul!
Gahra Raschedian
2022-07-22 22:27:33 +0000 UTCThanks for these videos. I always wanted to learn something about electronics (I really don't have much idea), and I know this will help me a lot. It is already doing it. By the way, one possible answer to the question "are we ever going to be able to get a completely vertical rise, a perfect square wave?" is: that depends on the resolution you need to have in time for your system. Thanks again!
J C
2022-01-31 18:31:17 +0000 UTCI really appreciate video because if I don’t understand something, I can just rewind it or just watch the whole video over again. I wish I had discovered this site years ago.
Steven Wolfe
2021-12-30 06:43:48 +0000 UTCThank you so much! Loved seeing how the vacuum tube works in an amplifier. Why they chose certain tubes as pre amps and most of all, how the push pull works, I have long been a lover of vacuum tubes but had yet to find such a nice easy to follow understanding of how it all comes together.
Jared Kusner
2021-06-03 14:56:33 +0000 UTCOr better yet just go single ended class A and skip all that.
jeffrey wagner
2021-03-09 03:41:28 +0000 UTCBecause you can not get tubes in npn and pnp like you can transistors. or complimentary pairs is more accurate. so you must invert half of the signal to amplify it then you invert it back,
jeffrey wagner
2021-03-09 03:40:39 +0000 UTCI understand that a 12AX7 has two triodes but why do we need a phase inverter at all?
Fred Winograd
2021-02-25 17:27:31 +0000 UTCPlays fine here.
Mr Carlson's Lab
2020-12-28 00:05:22 +0000 UTCError playing this video
Gareth lingard
2020-12-27 23:48:34 +0000 UTCAs a newbie to electronics.....a lot of this is going over my head....but I'll keep watching and hopefully it will start making sense....
Horst Hartung
2020-12-08 18:50:48 +0000 UTCIt's great to revisit these older videos! I've since built several iterations of square wave oscillatory circuits and have never achieved perfect rise and fall edges! We can get close to perfection, but nothing is perfect! I've since learned that it's always a case of compromise with circuits in the quest for perfection!
Adam
2020-08-05 07:44:46 +0000 UTCFantastic videos Mr Carlson! It is rare to find a true teacher and I am so glad to have come across you on Youtube. I've learnt a stack already which I am already using to restore a pair of Quad II amps and Quad 22 preamp and will use my new knowledge to better help out at our local repair cafe once I can get back to my work bench post Covid-19. I hope you and your family are staying safe and well. Thank you for your amazing work!
Keith Colin
2020-05-12 23:13:31 +0000 UTCthanks for the heads up about building a tube amplifier. That is why I signed up. That is what I want to do.
Gregory Pellar
2020-05-01 02:57:49 +0000 UTCPaul. Watching the video in the section re phase inversion, it appears from your oscilloscope that there is still a phase variance, say10 degrees? What causes this?
Pat McGuire
2020-04-06 16:36:42 +0000 UTCWhy can you not leave the transformer center trap at ground and use the FETS to supply the power. Hook 12volts to the drain and the source to the transformer and still use N-Channel? In my 38 years in electronic I worked with Hexfet pulser but really no other FETs. FETS were not covered, or just in passing, in my 1979 electronics school. So I am enjoying watching your old videos 8-)
David Kuhn
2020-04-04 21:59:16 +0000 UTCI am also wondering how the construction of the transformer effects current flow in circuit. Is current only in one direction?? Is it there only when oscillator closes and not there when open? Does the square wave go NEG on the oscilliscope trace? Probably dumb question and years too late. Its all good. Later
Terry l Fiala
2020-01-22 17:21:16 +0000 UTCMaybe it comes later in the video. I would like to see the voltage noted on the oscilliscope for each position of the contacts in the oscillator/vibrator. What would happen if we took that .47 uF capacitor out of the circuit. Is the discharge of that capacitor responsible for the downward deflection of the square wave in the upper trace?? That is what I am trying to figure out. The other thing that would help if I could visualize the flow and change of current in the circuit as the switching takes place.
Terry l Fiala
2020-01-22 16:48:50 +0000 UTCAt first I grinned at this, then the penny dropped; yes, if X and Y are sine signals, and Z is the time coordinate, then it WOULD describe a spiral if the amplitudes of X & Y were the same. Cool thought Charles!
Bill Rule
2020-01-12 01:22:51 +0000 UTCGood possibility. Most everything in nature is "round"
Mr Carlson's Lab
2020-01-09 13:57:45 +0000 UTCIf you could see a sine wave in three dimensions, would it look like a spiral?
Charles St Lucas
2020-01-06 23:05:46 +0000 UTCLoved it. Thanks!
Terry l Fiala
2020-01-04 06:11:05 +0000 UTCThat was good. Thanks Mr. Carlson.
Dan W.
2019-12-29 22:31:32 +0000 UTCI think I've been barking up the wrong tree. Dah, I think they're not electrolytic.
joram kalfa
2019-08-18 23:27:17 +0000 UTCMr. C...Crazy question. Re: Electrolytic capacitor of .1uF 400V...Is this a value that isn't common anymore? I need 5 of them for this Marconi tube stereo restore and I've searched hi and lo on the net without much luck. I know you said use .1 at 630 but I can't find those either.
joram kalfa
2019-08-16 20:30:55 +0000 UTCHi Joram. Those are digikey part numbers, I don't sell components. As for the schematic, you will have to search the net, I don't have a schematic for that model. Look for other numbers as well, IE chassis or series numbers, they are an alternate search.
Mr Carlson's Lab
2019-08-15 16:00:53 +0000 UTCI apologise for being a newbie. Am I getting this right? Are you selling these components or is this a referral to Digikey? Also, re: the schematic for this Marconi stereo...any idea where I could get one?
joram kalfa
2019-08-15 15:25:39 +0000 UTCHi Joram, and welcome! Just use .1 at 630 Volts. I have a list of verified components in one of my video's here. Use this list for quick access. Please note, this list only works as long as you are an active Patron. Here is the list, save it to your browser: https://rebelba42.lima-city.de/img/mcl/
Mr Carlson's Lab
2019-08-15 15:03:37 +0000 UTCSorry, I keep hitting return and it sends the comment. I scoured the net for a schematic. No luck. Are you at all familiar with this unit? It has .1uF @ 400V that I'm having trouble finding replacements for. BTW...I did fire it up with a current limiter(no smoke) but the current limiter(high watt light bulb) did light up a bit. Any comments or words of wisdom? Thanks.
joram kalfa
2019-08-15 14:13:47 +0000 UTCSorry....it has 4 6BQ5 with 2 6C4. It uses diode rectification.
joram kalfa
2019-08-15 14:09:47 +0000 UTCI just acquired a Marconi AM/FM stereo phonograph console model #4518 circa 1964. All tubes and all made in Canada if you can believe it. I am interested in restoring the power amp section. Upon initial visual inspection I can see that the caps need replacing. It has 4 6
joram kalfa
2019-08-15 14:08:06 +0000 UTCHello Mr. Carlson, great explanation of audio amplification here. One quick question though, on the schematic you created, you've put 2x 470k resistors on the inverted/non inverted inputs to the 6360 for 'biasing'. Can you explain why/what that is?
Sam Harris
2019-07-21 11:22:47 +0000 UTCGiven the need for a 50W 1.5Ω load can one use a 100W instead. I don't think that should matter, right? And a tube amp design from your 6360 / 2x 12ax7 demonstration would really rock the house!😎
Scott Croydon
2019-07-19 02:13:49 +0000 UTCThanks for your input Travis.
Mr Carlson's Lab
2019-07-03 23:23:01 +0000 UTCI an really wanting to see a 8-20 tube amplifier or 4 but i hopefully you make tube amplifiers be so nice and very nice to build a higher powered one 200 wpc + lol
overbuilt automotive
2019-07-03 14:53:38 +0000 UTCLOL! I just learned I need to buy a new power supply for my ham radio! That explains SO MUCH. I stood up and looked to see what my power supply said on it, sure enough, switching. If you have any suggestions for a reasonably priced linear power supply for a ham radio please let me know, I know a few brands, I bought this switching back when I first got my license over 10 years ago. Thanks! - KI4VVA
Devin82m
2019-03-06 22:59:45 +0000 UTCThanks a million, man am I getting my two bucks worth! ! ! ! Wifey is not really thrilled, she has been watching the budget very closely as of late, and with good reason, Workers Comp cut my paycheck in half last fall announcing that I am now considered retired. Funny, I don't feel retired but it has put an end to our winters in Arizona, and we are once again freezing in the Dakota winters. Ah well, I am getting old, as is my good wife of 50 years. Still, it is nice to be here for mom, who will be 93 next month. I should be up visiting her at the nursing home as I type but these videos have me hooked and I must go on. I have learned more in the last few weeks about the real life of electrons then I have for many a year.
Jerry Ericsson
2019-01-27 19:37:49 +0000 UTCHi Andy. If you are referring to the small peak at the rising edge of the wave form, that's known as "overshoot" and "ringing." This is common in these types of circuits, and the snubber capacitor tames this problem. This problem arises with stray inductance (leakage inductance) and capacitive issues within the transformer itself.
Mr Carlson's Lab
2019-01-18 08:27:41 +0000 UTCGreetings Paul, and thank you for another fascinating and educational video! I have a question concerning something I noticed while studying the traces shown of the vibrator circuit: When either of the contacts connect, its trace appears to peak slightly above the input voltage before stabilizing. And likewise, when that contact then disconnects, its trace appears to dip below zero before stabilizing. My expectation is that the voltage present across each contact's output during its respective half of the overall cycle would never go above the input voltage, nor below zero, but this doesn't appear to be the case. So what's causing this? Thanks for your help! -Andy P.S. - I apologize if this was asked/answered already -- I searched the comments, but couldn't find it if it was.
Andy S
2019-01-17 22:40:28 +0000 UTCGreat video Paul! I was only asking you about solid state vibrators a few days ago and found this video! My power supply I built was rather crude and changed frequency with battery voltage. So I took your advice and opted for an external oscillator to maintain a stable frequency regardless of battery voltage drop. I decided upon the 4047 chip in Astable mode. I'll see how this experiment goes! I'll also try the TL494.
Adam
2018-12-22 13:30:56 +0000 UTCHi John. Most of these units are pretty tolerant to that small variation. If you find they get to hot, you may want to use a Variac, or a buck transformer.
Mr Carlson's Lab
2018-11-26 02:09:35 +0000 UTCQuestion: I have a Dynaco tube preamp PAS3X and two Dynaco Mark III amplifiers. They were designed when home AC current was about 115 volts. Now home AC current is 122 or higher. Q: do I need a variac to decrease the incoming voltage to the preamp and amps to prevent overheating and premature damage to the tubes and the rest of the units? Thanks !
NovemberBravo
2018-11-25 11:16:04 +0000 UTCNeed to find a great knowledge base to building "Great" Hi end Tube amps!
don
2018-11-21 23:56:05 +0000 UTCReally need to get back into electronics and learn all I can before I retire, 56 now, and willing to lean.
don
2018-11-21 23:55:15 +0000 UTCGlad to share Gary! The 6360 is a great little tube.
Mr Carlson's Lab
2018-11-17 22:16:18 +0000 UTCHey, Bo. You are describing a "motor-generator," which is a long-established way to convert DC current to a beautiful AC sinusoidal current. Although a motor-generator has some typical drawbacks associated with rotating equipment (bearings & brushes that can wear over time), it also has a cool advantage. If the DC supply to the driving motor is momentarily interrupted, the rotating inertia of the machine keeps generating a constant AC output (although the frequency will drop as the rpm falls off). So a motor-generator set is kind of like an "uninterruptable power supply" of AC output even if the DC supply encounters momentary voltage fluctuations.
Gee Bee
2018-11-17 04:46:02 +0000 UTCAs a beginning vacuum tube guitar amp guy, I loved your little push-pull audio demo. I've never seen a dual beam power tetrode before!
Gee Bee
2018-11-17 04:36:23 +0000 UTCIf you were going to design a mechanical switching power supply, surely spinning some kind of motor/generator at high speed would be much more audibly tolerant or am I totally on the wrong track again?
Chris (Bo) Bodragon
2018-10-26 01:43:00 +0000 UTCHi Jason. The on time is affected by the weight and contact spacing. More voltage applied will also affect this, as it will swing the reed harder (only in one direction) minus bounce.
Mr Carlson's Lab
2018-09-27 23:53:16 +0000 UTCWouldn’t the shorter on-time be mechanical in nature. You’re essentially changing the fulcrum with the coil contact shortening the spring to weight forcing it to react quicker. Maybe you made that point, but I took it as an electrical phenomenon. Can you clarify that? Is it possible that both are in essence working together to shorten the on-time?
Jasin Colegrove
2018-09-27 15:43:49 +0000 UTCGreat to read!
Mr Carlson's Lab
2018-09-06 09:40:24 +0000 UTCAnother nice lesson Paul, thanks! This is a good way to learn electronics and gives me new perspectives. I can't wait to actually work on an old amplifier.
Robert Calk Jr.
2018-09-06 05:24:01 +0000 UTCHello Paul. Just wondering if you would be interested in my excess tube stock. I bought an estate and it came with 27 big boxes of tubes. I've sorted and tested all the tubes and kept some but want the others to go to good use. My email is dkelsea@sbcglobal.net I'm sure you have many tubes and thought you could use these for training and such. Maybe you could throw a board or 2 my way. Just let me know. Dave
David Elsea
2018-05-14 16:59:37 +0000 UTCLots of tube stuff coming Jason.
Mr Carlson's Lab
2018-04-12 11:17:32 +0000 UTCI hope your still planning to build the tube amp very interested in Vaccum tube stuff I dont know why I just think they are quite beautiful.
Jason Martin
2018-04-11 23:15:02 +0000 UTCHi Jerry. The order is from the bottom to the top. You will find that topics move around a bit, as there are many different interests and levels of experience here. Here is a list the Reb (Ralf) put together, you may find this useful: <a href="https://rebelba42.lima-city.de/img/mcl/" rel="nofollow noopener" target="_blank">https://rebelba42.lima-city.de/img/mcl/</a>
Mr Carlson's Lab
2018-03-07 15:49:34 +0000 UTCIs this video a part of the electronics learning series that you have going on here? If so, is this a continuation of the "50's Switching Power Supply" video? What is the order of the electronics learning series? Or, are the videos already in order going from the bottom to the top? Are all of the videos here a part of the series? Thanks!
Jerry Pemberton
2018-03-07 13:34:43 +0000 UTCHi Dave, If one half of the phase inverter is acting like a cathode follower, (under unity gain) you don't want the other to differ to much, or you get imbalance.
Mr Carlson's Lab
2017-12-30 01:12:07 +0000 UTCLooking at the signal on the plate of the 2nd half of the 12AX7 (the phase inverter), it looks like the plate voltage was about 20 volts P2P. This is roughly the same P2P voltage as the signal applied to the grid. Why was there no amplification on the plate?
Dave Bacon
2017-12-29 20:15:50 +0000 UTCThanks. That’s clear now.
bully1
2017-11-19 16:37:33 +0000 UTCHi, You will find a snubber capacitor across the contacts of most vibrators. When the contact opens, it takes time to charge the snubber capacitor, this requires current, and stops contact arcing. Keep in mind this is a fine balance with the amount MFD's the capacitor has. Too many MFD's or (uF,) when the contacts close on the opposite end, they have to short the caps residual charge. This creates sparking as well. This arrangement forms a sort of LC network... Kind of like the condenser in a breaker point ignition, which is usually around .3uF at 1500 Volts. Snubber caps in a vibrator type power supply are usually between .001 and .01 uF depending on the load being drawn on the secondary. You will find these snubber caps also reduce hash or RFI as well, as they round the edges of the square wave (time increase) and reduce spikes and over shoot.
Mr Carlson's Lab
2017-11-18 19:46:13 +0000 UTCYes thanks, that does help. Can I ask you a further question? If I understand this correctly as the magnetic field collapses the voltage on the top part of the transformer reverses and the current reverses. Where does that current go? Does it jump across the top contacts to the vibrator? Many thanks for your patience.
bully1
2017-11-16 19:07:46 +0000 UTCWhen the contacts open, the transformers magnetic field collapses and sends current back out the transformer leads. Does this help?
Mr Carlson's Lab
2017-11-16 16:44:15 +0000 UTCHi paul. I'm having trouble with some basics. The transformer is centre tapped with ground at the centre. Like others i'm struggling to see how their is a negative trace on the top trace when the top contacts are broken and the bottom contacts are in place. As no current is flowing between the centre tap and the top contacts I would have expected the voltage between the centre tap and the top contacts to be zero. Your trace is showing a negative voltage. This of course assumes the oscilloscope top trace is connected between the top contacts and the centre tap. What am I missing?
bully1
2017-11-16 09:42:11 +0000 UTCSo you have to talk to the old Cro in order to gain the benefit of cooperation? Here's a little spell which might help alleviate the problem without the need of booting while uttering a range of threats and curses: Deus ex machina! Deus ex Machina! Quod ad me pertinet Machina mea est! ;) Its a form of exorcism which should work for most diablolic instruments, and hopefully then quell the vagaries of spurious intermittencies; and thus permit even backyard trash, to live on without expensive services, overheads and expenditure, almost void of dearly needed cash.
Frank
2017-11-01 16:41:42 +0000 UTCHi Jeff. Most scope inputs are rated around 400V Check your scope to make sure though.
Mr Carlson's Lab
2017-09-18 11:04:10 +0000 UTCAnother awesome video. I do have a couple of questions though. When viewing the signal, with an O Scope, is there a point in the circuit that could damage the Scope? Are there optimal points that should be chosen to view the signal and others to avoid? I'm referring to tube circuits. Thank you for your hard work and dedication.
Jeff Tremblay
2017-09-16 21:19:30 +0000 UTCThanks for your input Jemima. Cathode Ray Oscilloscopes will be around for a while yet, as they still have purpose. The newer digital scopes are good for learners, as they spell everything out.
Mr Carlson's Lab
2017-07-27 02:50:01 +0000 UTCI've never had the opportunity to work with cathode tube oscilloscopes. Do you think that they will ever go obsolete? (I do however know that one of the labs in my university has them... I should probably try and use them) The issue I have with digital oscilloscopes is the sheer number of buttons. it can be quite intimidating for a learner. I was wondering if in the near future you could do a simple tutorial on how to use oscilloscopes? (both digital and analog) and also explain when it's ideal to use an analog/digital scope? I feel like I'd prefer the analog oscilloscopes! (they look pretty :) ) I've seen a cathode ray tube once inside by old TV, I remember the electrician who was repairing it telling me about how dangerously high the voltage was. Either way, I'd be interested in a how to oscilloscope video :) ... or if you know of any manuals on the internet a link would be great!
Jemima Khan
2017-07-26 16:36:28 +0000 UTCHi Bjorn. When the vibrator is designed, they spend quite a bit of time balancing the reed, so the times are pretty close between both sides. This is important so one side (winding) of the transformer doesn't see more time (Current supplied) than the other winding.
Mr Carlson's Lab
2017-07-17 19:00:44 +0000 UTCOn the side with the shorter closed time. How much affect do you think the coil actively pulling the spring off the contacts has on shortening the time those contacts remain closed??
Bjorn de la Cour
2017-07-17 15:33:09 +0000 UTCNo question is silly, always feel free to ask. The transformers job is to transform impedance. The plate impedance of a vacuum tube circuit is much higher than that of a speaker. The transformer attempts to "match" the impedances. Modern gear utilizes transistors, and they are low impedance devices, so in many cases no transformer is needed. The transformer has that bonus of blocking the high voltage as well.
Mr Carlson's Lab
2017-06-30 00:10:40 +0000 UTCThe transformer at the end of the audio amlifier stage - is it needed to get "rid of" the high voltage? Is that the reason all these old devices have so many transformers?
Schlomo Aschkenasy
2017-06-29 18:29:17 +0000 UTCI am totally new to tubes so sorrry if this is a silly question:
Schlomo Aschkenasy
2017-06-29 18:27:34 +0000 UTCThis is correct, there are two probes attached into circuit.
Mr Carlson's Lab
2017-05-13 18:03:26 +0000 UTCYou're seeing the other end of the transformer, on the negative side. (you're seeing a Phase inverting affect)
Mr Carlson's Lab
2017-05-13 18:02:23 +0000 UTCAnother thing that puzzles me: If the flat traces with the vibrator turned off represent zero volts, then why does the trace with the vibrator ON appear to fall below zero?
Paul Dochow
2017-05-13 15:32:51 +0000 UTCSo, would it be accurate to say that we are seeing the same square wave (with "noisy" vertical traces) seen from two different points in the circuit?
Paul Dochow
2017-05-13 15:28:33 +0000 UTCHi Paul. This is quite a common way of thinking, just due to many years of incomplete explanation. Here is the answer: There has to be a full sine on each side to have low distortion audio, if you look at the spacing between the sine of the upper trace, and the lower trace, you will see the upper bump (upper trace) out of time with the upper bump (lower trace). This is indicating the 180 degree phase difference.
Mr Carlson's Lab
2017-05-10 18:48:25 +0000 UTCThe scope trace looks to me like two full-wave traces. I would expect to see two half-waves. What am I missing?
Paul Dochow
2017-05-10 17:35:29 +0000 UTCHello Michael. The isolation transformers I own are all really old. Hammond makes a real good transformer. The best place to find these are ham radio swaps. A good isolation transformer is usually pretty heavy, and costly to ship.
Mr Carlson's Lab
2017-04-04 06:57:59 +0000 UTCThank you for responding! Do you have a specific recommendation for an isolation transformer? Your videos and detailed explanations are truly excellent.
Michael Barg
2017-04-03 18:20:08 +0000 UTCHi Michael. It looks like a neat device, but I have never owned one.
Mr Carlson's Lab
2017-04-03 16:52:02 +0000 UTCPaul, you've mentioned using an isolation transformer on the bench to prevent inadvertent shock hazards, especially when working with power supplies and oscilloscopes; safety must be first priority. There are some on eBay and Amazon, but they tend to be rather pricey. Would you please share your opinion of older devices, such as the RCA TV Isotap WP-25, which are affordable but definitely vintage? Thank you!
Michael Barg
2017-04-03 03:35:42 +0000 UTCLooking for some guidance, Paul. Could not find ratings for the PS transformer or the H/W diode block, so I decided to run some experiments. The transformer was originally on a small chassis and wired to a 7 pin miniature socket, so my guess is that it probably has enough current to work with on a two-tube version of your demo amp, albeit at reduced power. The preamp/splitter tube will be a 6SN7GTB which tests out strong on my B&K. Experimenting with various load resistors and a 270mf Nichion, I got 130ma @ 131VDC with load of 1K for several minutes with no transformer or diode block problems .e.g. diode cool and tranny lukewarm to the touch. Scope shows less than 5% ripple but its hard to tell what is true ripple vs shack noise. I think the tranny will be OK but solicit comments from the group . Q : Looking at the 6SN7GTB data sheet it shows what look like two different voltages for triode A and triode B under the Class A heading. Are they just min/max values or something else? Also, what, if any, software do you use for preparing the schematics? tnx
chuck yahrling
2017-03-31 15:01:31 +0000 UTCLooks like you're on your way! Lost of "locktal" sockets on that chassis. I always liked those tubes, very common in Philco radios and car radios alike.
Mr Carlson's Lab
2017-03-29 13:42:16 +0000 UTC11% Done on my Build-Along. Spent last few days getting parts together and have a basic chassis ready for parts and tubes. "<a href="https://ab1vl.com/" rel="nofollow noopener" target="_blank">https://ab1vl.com/</a>
chuck yahrling
2017-03-28 20:46:26 +0000 UTCGreat link Chuck!
Mr Carlson's Lab
2017-03-27 13:10:50 +0000 UTCTube Guides galore while looking for RCS tube guides I hit on this link, a new one for me: <a href="http://www.bunkerofdoom.com/tube/man/" rel="nofollow noopener" target="_blank">http://www.bunkerofdoom.com/tube/man/</a> Amazing collection of PDFs for many different makes including vintage tubes. HTH
chuck yahrling
2017-03-26 18:35:43 +0000 UTCZooming in on a falling square wave edge. Seems like the angle of attack should not look so different.
Stephen Martin
2017-03-13 04:23:00 +0000 UTCI am not posting this for a response just an observation. Every book I have read talks about how important it is to match impedance but not why and not what cases. That simple statement of when a "significant amount of power is transfered ..." answered a question that has pestered me for a long time. Thanks, because that, I can now calculate and determine when matching is necessary.
Carl Davis
2017-03-10 06:49:11 +0000 UTCThe input impedance match from the signal generator to the grid of the triode is not all that important for testing purpose. The termination (8 Ohm) of the output transformer is though. Any time a significant amount of power is transferred from a source to a load, an impedance match is important.
Mr Carlson's Lab
2017-03-10 03:34:08 +0000 UTCI really like the build, my question is on the input impedance of the amp. My understanding is that it needs to match the output impedance of the signal generator you fed the sine wave from. I am assuming 600 Ohms. Just like you used the transformer to drop to an 8 Ohm output for your 8 Ohm load, How did you work the magic to match the amp input impedance to the output impedance of your signal generator. Or am I just completely off base?
Carl Davis
2017-03-09 23:18:55 +0000 UTCHi Patrik. Impedance conversion is the reason tube amplifiers have output transformers. The impedance of most vacuum tubes is quite high, the impedance of most speakers is quite low. The OPT "transforms" this impedance to match the two devices for maximum power transfer. In OTL service or "output transformerless" service, you need many tubes in parallel to bring the impedance down. The best solution is to use tubes with an already low impedance like the 6AS7, 6336, or a 6C33. Putting a bunch of these in parallel will get you to a target impedance quickly. These tube can be called "low mu triodes"
Mr Carlson's Lab
2017-03-07 08:11:12 +0000 UTCI am kinda new to electronics and interestingly, a few weeks ago I started to consider SMPS as an alternative to OPT, but since I don't know that much about SMPS and very much learning about tubes and glad I found Mr Carlsson's lab and the patrion page, I want to ask a question. Some advocate that a tube amplifier in class A mode or Ultra Linear mode absolutely must have a output transformer. So my question is: Why is this ? As we have seen, SPMS was around in the 50's
Patrik Lövström
2017-03-05 22:41:01 +0000 UTCMr. Carlson, just what we needed! Thanks.
Victor M. Salcedo
2017-03-05 22:36:05 +0000 UTCThanks George!
Mr Carlson's Lab
2017-03-02 18:46:49 +0000 UTCYour style of explanation resonates with my style of learning and I seem to have just enough electronics knowledge/vocabulary to follow along and to be constantly amazed. Thanks!
George Ray
2017-03-02 18:11:07 +0000 UTCI found this fascinating. Huge amount of information crammed in the video.
David May
2017-03-02 16:44:36 +0000 UTCHi Ramcur, I have recently been gifted a Tek 465B scope. You must use a piece of coax to connect and set the scope right. It does work and my friend still may not believe me. I will show him when his motor for his vintage Icom 765 comes in for the tuner and I gift it to him. He said that was unobtanium too. Ok so here is the point, look at pics of the old radios, notice the untouched ones all have the black band on the wax cap installed a certain way. This goes for the "Bumble Bee" type as well. So, even if the difference is minor as our instructor has pointed out, I still prefer to install as original to ensure a best possible result. I always taught my technicians in the maintenance industry "Quality Fit and Finish", and our repairs often exceeded normal service lives.
Ted Copp
2017-02-26 18:27:14 +0000 UTCThe second triode just acts as a phase inverter and is close to unity gain. The action has to be like this, in this configuration due to one part of the inverter acting like a cathode follower. (cathode followers are close to unity gain only) If there was amplification at the plate, there would be an imbalance in the phases.
Mr Carlson's Lab
2017-02-24 08:33:23 +0000 UTCYes, think this needs clarification
Bob Fuller
2017-02-24 08:14:11 +0000 UTCHi Ismael, no need to be sorry. This course caters to many different levels of electronic experience, therefore I mix it up so everyone feels a parts of this. As I get closer to the goal, I will be here on Patreon more often and video's will get more frequent. I'm really looking forward to having the time, to share what I know on a deep level. I hope this answers your questions.
Mr Carlson's Lab
2017-02-24 07:47:00 +0000 UTCAre these videos the actual Electronics course? I thought we would start off with the basics first, sorry I am new to this Patreon
Ismael Cardenas
2017-02-24 04:44:59 +0000 UTCHi Paul. Great video. I have a question about the amplification in this circuit. The 344mv signal is applied to the grid of the first half of the 12ax7 tube with 24 volts ac output at the plate. Now 24 volt ac is available to the grid of the second half of the 12ax7 with what look like about 20 volt ac output at the plate. I understand the phase inversion but I don't understand why the first triode amplifies while the second triode does not amplify ? Thanks for quality and effort you put into your videos.
Martin Malia
2017-02-24 03:31:37 +0000 UTCExcellent videos. I'm enjoying the course a great deal. I never noticed the resemblance between a tube amp and a switching power supply either. It's very nice to look at a schematic and start to understand areas as functional blocks, rather than just a bunch of components connected together. That's exciting! On another topic, in some of your videos you mention lubricating the shafts of pots - what lubricant do you use? Thanks!
Seth Glassman
2017-02-22 21:59:13 +0000 UTCLooking forward to the tube stuff. FETs and BJTs are abundantly documented and explained, tubes not so much, and methinks you're the perfect man to explain it.
Steffen
2017-02-20 00:11:00 +0000 UTCIt is a nice color, the camera is really sensitive to it as well, I have to turn the scope brightness almost completely off when I have the camera pointing at it, yet it looks super bright in the video.
Mr Carlson's Lab
2017-02-19 07:07:05 +0000 UTCLoved the colors of signals in the first scope
Alberto Rusic
2017-02-19 01:02:30 +0000 UTCNew to electronics here. Also, I"m studying for my Technician's "Ham" license. I appreciate the detailed explanations.
Rick Estep
2017-02-18 03:37:28 +0000 UTCThis was great..........really cleared up some of the jargon to physical reality "push/pull".
Shawn Rice
2017-02-17 16:13:50 +0000 UTCThank you so much for this! You are the best..... Looking forward to more...
Geoffrey Wasteneys
2017-02-17 03:26:55 +0000 UTCThank you Paul. Another excellent educational video. Would it be possible to have a pdf of the schematics available to download?
Stephen Studley
2017-02-15 14:41:51 +0000 UTCThanks Paul. Brings back memories of my early tube days. I'm from old school transition from tubes to transistors (ie early 60's.)
Amos McDaniel
2017-02-15 06:57:20 +0000 UTCThanks Paul...
Charlie Tennison
2017-02-15 04:00:47 +0000 UTCGreat vids Paul, not loving the tubes, lol. Greek to me. Ill change it to mosfets for my simple mind.
Roger Kerr
2017-02-15 01:54:29 +0000 UTCSorry Paul, you had already answered that question with Steven , didént se that ....was curious to how much "down" you lowered it :-) and about maximum 100ma you say ....i´ll put this together in my workshop to follow your thinking - have some Tesla QQE03/12 wich should be roughly the same tube and se how this performs :-)
Anders "SM7HCE"
2017-02-14 22:06:18 +0000 UTCHi Ted. I will try to answer questions here as much as possible. You can't use an oscilloscope probe to do this, you need a piece of coax with minimal exposed ends, connected directly to the scope input. Use your scopes highest vertical sensitivity. In many cases the outside foil won't mean much, but in some RF application, and in sensitive AF stages, It can.
Mr Carlson's Lab
2017-02-14 18:20:51 +0000 UTCInteresting, I never made the link before between switching power supplies and tube amps driving the output transformers
Alexandre Côté
2017-02-14 17:15:37 +0000 UTCI have a question somewhat related to this about capacitors. My friend has an O scope and we tried the "Hum" antenna method to identify the capacitor polarity as with the yellow axial often used to replace wax. We could not get a reading. If the black band on an original is polarity, then can I simply use an electrolytic so I don't have to guess which way to install the other types. What do you do if you don't have the equipment to check them? Sanding a spot down to the outside to test which lead is what sounds like a bad plan to me. Also, where should we ask general questions when they come up?
Ted Copp
2017-02-14 16:43:13 +0000 UTCPaul, Great stuff. I really enjoyed this and will revisit it again. Please keep it up.
William R. Klem
2017-02-14 14:52:20 +0000 UTCHi Paul - Great video as usual :-) one question, are you putting a negative voltage on the bias in this schematic, and if so - how much?... / A
Anders "SM7HCE"
2017-02-14 09:48:46 +0000 UTCNot an expert here... so I have few basic questions concerning the signal trace of either channel (lets pick the upper one for convenience) when the center tap of the transformer was grounded (no fats involved). What is the voltage value about the end of the dead time? Is that ground? If so, why does it become -vdc when the other side of the primary is being connected to +vdc? What is the purpose of the .47 uF cap? Is that cap an electrolytic one? Thanks Mr. Carlson.
Matteo Guglielmi
2017-02-14 00:06:11 +0000 UTCVery interesting really enjoying your videos if only you had been the teacher at college would have been easier to understand. I work in electronic repair on guitar amps and synthesisers mainly. Your switch mode work has bern very usefull. my grandad taught me about valve amps especially safety side. I've rebuilt a valve oscilloscope a telequipment S51b but I'm going to check all the poly propylene caps incase any are backwards. Thank you so much for producing this course best cup of coffee yet.
Sam wright
2017-02-13 18:52:26 +0000 UTCWow! I am learning so much. Can wait for another episode. Great work on your explanation. Thank You.
Andre Gopee
2017-02-13 16:22:00 +0000 UTCThanks Timothy!
Mr Carlson's Lab
2017-02-12 23:47:27 +0000 UTCVR tubes are actually quite silent if the design is good. I have used them in my own audio designs. 0B2's look nice as they glow orange.
Mr Carlson's Lab
2017-02-12 23:47:05 +0000 UTCHi Jon. As things progress here, there will be more information available as I have more time to spend on projects. I try not to "over do" the quantitative end of things, as I'm always searching for the balance in the build of these video's (it's a fine line). In an actual amplifier build, there will be quite a bit of quantitative and qualitative data (math short cuts) and more.
Mr Carlson's Lab
2017-02-12 23:44:33 +0000 UTCGreat job Professor !
Timothy W Blocker
2017-02-12 23:39:33 +0000 UTCHi Paul. I like the blue glow of VR tubes. You mentioned your design of the power supply for an audio amp would include a regulated screen supply. My question: Do VR tubes produce too much noise for a high end audio amp?
Douglas Tees
2017-02-12 20:30:09 +0000 UTCI really need to get an oscilliscope,lol....I have built a couple guitar amps, and I love to see these videos going from tube technology, which I understand, to solid state, which is still foggy with me :)
Gary Eggleton
2017-02-12 20:15:25 +0000 UTCI really am enjoying your careful qualitative descriptions of how things work. Those descriptions and the sheer work you put into them really defines you well and I like it very much. One thing I'd like to see more of, and I do not think it would be appropriate to include within the same videos but would either require a separate web page or else a separate video, would be a detailed and quantative design walk-through. I think this is especially needed for vacuum tubes where grid currents are perhaps a little trickier to understand than are BJT base currents (or even MOSFET gate currents) for those of us with more experience in semiconductors than vacuum tubes. (I'm assuming there is a grid capacitance involved here, though, more similar to MOSFETs than to BJTs.) Vacuum tubes also offer, commonly, tetrode and pentode configurations and these are not commonly available in semiconductors. So there is a great deal of interesting design information to pass along there, as well. Is it possible to consider a quantitative design walk-through followed up by an actual build-up of an actual system so that quantitative design estimates can be compared with achieved results, as well?
JonK
2017-02-12 20:13:37 +0000 UTCThanks Mathias! I will be here a lot more often when I reach that goal. I have so many projects to share, really ...don't think I'll ever run out.
Mr Carlson's Lab
2017-02-12 17:44:41 +0000 UTCHi Steven, "about" negative 20V bias. The transformer was about 8.5K p-p, 10 K would be more optimal. The tube did it's best with "slight color" in the plates. Plate current should not exceed 100mA total, slight color showing at about 80Ma @ 285 V B+. I should mention that this Current is "Total Draw" of the entire circuit running, so the Ma meter is in the B+ lead to the entire amp. Stand alone measurements of the 6360 were not made for the demo.
Mr Carlson's Lab
2017-02-12 17:41:46 +0000 UTCThanks for the video never understood all that happened a circuit (more into valves (sorry tubes - across the pond here)) but understand them better than solid state. The 6360 looks like a very versatile tube and it will help with understanding for all of us to use the same tube in different circuits. Very much interested in 40 watt 6360 power amp. Well off to do some research on the 6360 tube right now. What was the A-A load and bias voltage you were using? As I have a regulated Solartron power supply which could be used for this.
Steven Calver
2017-02-12 11:10:07 +0000 UTCLove watching your video's. Thank you very much for your effort!
PJzzz
2017-02-12 11:06:54 +0000 UTCThank you for the great video!
Roberto Abdelkader Martínez Pérez
2017-02-12 10:40:35 +0000 UTCExcellent video, great teaching skills. Had to upgrade my support level! I have an old German Blaupunkt radio from the 1950's, it still works, but with a few problems, I hope to be able to restore it one day.
Mathias Chapuis
2017-02-12 09:58:55 +0000 UTCMy reason for learning more about electronics was to build audio amps, this is great. Unfortunately it also shows me that I know pretty much nothing at present! Haha.
Ash Powell
2017-02-12 09:54:44 +0000 UTCThanks Jurgen!
Mr Carlson's Lab
2017-02-12 06:42:40 +0000 UTCIn a NPN transistor amp circuit if you take the output off the collector it is inverted in phase; if you take it off the emitter it is in phase. In a Vacuum tube same thing. if you take it off the plate inverted, if you take it off the cathode non-inverted
IMSAIGUY
2017-02-12 05:31:14 +0000 UTCMy question is will a signal all ways get inverted when it gets amplified through a tube ?
Grant Fullen
2017-02-12 02:48:41 +0000 UTCGreat video--thanks!😀
Don
2017-02-12 01:09:00 +0000 UTCGreat!
Mr Carlson's Lab
2017-02-12 00:54:42 +0000 UTCI'm looking forward to building circuits with them. The nice thing about this tube.... It works all the way to VHF, so we can build multiple projects with this tube and watch how the circuits change around it with rising frequency, (AF to RF transition.) There may have been a bit of pre-planning there :^)
Mr Carlson's Lab
2017-02-12 00:53:29 +0000 UTCYou are absolutely correct. The square wave is the result of many sinusoidal wave forms all put together.
Mr Carlson's Lab
2017-02-12 00:48:02 +0000 UTCThe B+ runs directly to the center tap, then to the screens through a 4.3K Ohm resistor. As mentioned, If I were to build an amplifier with this tube, I would have a regulated screen supply. The screen Voltage drops when signal is applied to the control grids (the screen is drawing current.) In the configuration you see, the screen is above 200V (zero signal) and will drop below 200V when signal is applied to the control grids. This variation would lead to increased distortion of the wave form.
Mr Carlson's Lab
2017-02-12 00:45:21 +0000 UTCGlad everyone is enjoying, already started on another!
Mr Carlson's Lab
2017-02-12 00:35:18 +0000 UTCGreat video, excellent lesson, nice testgear ;)
Jürgen Driessen
2017-02-11 23:46:11 +0000 UTCabsolutely amazing! what a great vid. thanks
Russell Smith
2017-02-11 23:28:54 +0000 UTCThanks for doing this course in small portions for deeper understanding. Great Job! I'm not sure, but is the B+ Path over the 4.7K Resistor in the schematic, the positive supply for the Screengrid i've noticed in your Video "How A Tube Works"?
Reb Elba
2017-02-11 23:02:59 +0000 UTCSuper video, learn a lot .
Bruce Harwell
2017-02-11 22:30:09 +0000 UTCFunny, my school time is surficing again, building the square wave out of multiple sinusosed waves, math one on one... I remeber an asingmant tracing it of screen from a ZX81. You had to add waves in steps. Tedoius work, with a small program a lot faster.
Joop Terwijn
2017-02-11 21:43:56 +0000 UTCThank You Outstanding video
Wayne Carlson
2017-02-11 20:09:43 +0000 UTCGreat vid! Makes me want to build a radio or something :D .
KW
2017-02-11 18:59:05 +0000 UTCAwesome video!! Thank you!!
James Westhoff
2017-02-11 16:58:51 +0000 UTCThank you for another great video, loved it superb!!!
Billy Cullen
2017-02-11 16:42:54 +0000 UTCGreat video. I was hoping we would build a tube amp. Terrific!
Douglas Tees
2017-02-11 16:37:10 +0000 UTCanother great video, it would be cool to see an audio amp build
Luka Kosanovic
2017-02-11 16:06:28 +0000 UTCThanks for a great video!
Ole André Noss
2017-02-11 15:57:28 +0000 UTCI do hear fan noise, however the voice level seems fine. Maybe the voice level is just not as distance from the extra background noise making it seem lower in comparison? I played this video and a couple older videos at the same volume level and the voice level is the same.
Jacob Peterson
2017-02-11 15:40:46 +0000 UTCThis was a good start to my Saturday morning. The 6360 tube is very interesting.
Michael Lloyd
2017-02-11 15:37:41 +0000 UTCThanks, glad you enjoyed!
Mr Carlson's Lab
2017-02-11 15:33:50 +0000 UTCgreat video !!
larry justice
2017-02-11 15:20:22 +0000 UTCFascinating...great explanation & analogies !
Erik G
2017-02-11 15:05:07 +0000 UTCOutstanding!!!!
Troy Pelton
2017-02-11 14:59:15 +0000 UTCI would love to see you designing an audio amplifier :) to the audio: i didn't notice any other noise than the fans in the background. did you mean that Ole?
Robert Valdimarsson
2017-02-11 14:56:52 +0000 UTCIt seem to me that there is something strange going on with the audio on this movie?! I noticed it already in the first few seconds, quite a bit of white noise - at the same time the voice level is substantially lower compared to all your other videos... I don't know if this is just me, or if someone else can confirm...
Ole André Noss
2017-02-11 14:10:27 +0000 UTC
