Power Supplies, Part 3: Full Wave Bridge Rectification

[@ernestschultz5065]

Uncle Doug is like a genius

[@UncleDoug]

You are too kind, Ernest, or at least that's what my wife says ;)

[@mitchmason8386]

Uncle Doug thank you for your time on these videos I really appreciate it.

[@UncleDoug]

You're welcome, Mitch.

[@sabledriver]

Great explanation. The combined use of drawings, actual components, then, visual with the O-scope brings it all together. You are a talented instructor in many ways. Thank you for your time and effort!

[@UncleDoug]

+sabledriver You're welcome, SD. I like visuals too, so it seemed like a natural addition to a technical video like this. Thanks for your nice comments.

[@misterjimminyman]

I'm 38 now, but watching these transports me straight back to being 12 again, in the company of that wise, knowledgeable uncle filling my head with wonder and fascination and inspration. Thanks so much Doug!

[@UncleDoug]

What a nice compliment. Thanks so much, SP :)

[@TheRandomDave]

Had you been my electrical engineering instructor in school, I'd probably have stuck with it instead of going into life sciences. your teaching methods are top tier.

[@UncleDoug]

Thanks so much, Dave. By coincidence, my education was in Biology and Chemistry.....perhaps this is why we're "in tune" :)

[@DeadKoby]

Uncle Doug: Explaining really nerdy stuff without making it nerdy. Cheers!

[@UncleDoug]

+DeadKoby Thanks, DK. That's a very nice way to put it :)

[@jenniferjohnson708]

As an RC airplane enthusiasts of many years I completely understand the allure of drones. A most welcome inclusion into the videos. Great series of videos. I am still looking forward to your discussion of capacitors. Thanks for the great lesson.

[@UncleDoug]

+Jennifer Johnson You're welcome, Jennifer, and thanks for the very nice comments. The capacitor series is in the works and should be out in the near future.

[@Denvermorgan2000]

Im getting an education without going to school thanks Uncle doug i took an NRI correspondence course when i was young and this ties right into that.

[@UncleDoug]

That's good news, Denver. Continued success with your self-education.

[@Denvermorgan2000]

@@UncleDoug Thanks.

[@pvj300]

Your channel is a gem. I’ve learned so much more from your vids than even from building amplifiers. Keep up the great work!

[@UncleDoug]

Thanks so much, VJ. We will :)

[@NukeClock]

Your submission rate is reaching critical frequency, Dave. If you keep this up Im going to learn something new every day and I dont know if my brain has enough capacity for that. But seriously, I wish I had you as a teacher back in my youth. You are great at this and I want to thank you very very much for your effort.

[@UncleDoug]

+NukeClock You're quite welcome, NC. Rusty and I go through periods of interest in other hobbies and then we return to tube amps with renewed enthusiasm......as you are witnessing. We're really glad you enjoy our productions :)

[@steelcity321pb6]

You will not believe how much I have enjoyed watching Parts 1 to 3 of this series: absolutely superb Doug. Since you have mentioned voltage doublers for part 4, I look forward to my scant knowledge of the Villard Multiplier, the Cockcroft-Walton Multiplier; and the Greinacher Multiplier being refreshed: it was over forty years ago I first learned about those circuits whilst I was at college learning radio, and television, servicing. You were certainly right about Lucas electrical parts being in some ways wanting. I owned a BSA 175cc motor bike: it could have been a very reliable machine had it not been for the Lucas electrical system. I often used to wonder whether Lucas, Hunts capacitors, Mazda valves…and others I could mention, were in league with each other LOL. 73s de Phil.

[@UncleDoug]

+SteelCity321PB Thanks so much, Phil. It's great to hear that you enjoyed the videos. They're all really just a prelude to the Voltage Doubler with Dual Filament Transformers (Part 4), which is a very interesting and useful circuit. As far as Lucas being in league with anyone, I think it's generally conceded to be with the Devil himself (i.e. the "Prince of Darkness").....their products are almost inconceivably unreliable.

[@GuteisFinger]

Why do the Brits love warm beer? Lucas electrics.

[@UncleDoug]

I never heard that one before, Carl.....but can definitely understand it.

[@GuteisFinger]

Uncle Doug Having ridden a 750 Norton Commando w/ the 10:1 head from London to Athens and back when I was little, I can't say to. little about Lucas electrics. Glad to share the grin Uncle Doug.

[@UncleDoug]

That sounds like a wonderful ride, Carl. I assume it was made only during daylight hours :)

[@audiotechlabs4650]

Ah if only solid state rectification would produce the coveted "sag". I welcomed the drone tutorial. Rusty and Jack seem to have a nose for new and exciting things to do in Texas. Great as always! Thankz

[@UncleDoug]

+Audio Tech Labs You're welcome, ATL. Rusty is working on some sag experiments.....but they tend to involve his fat tummy :) Glad you liked the drone digression. I will include some more in future videos.

[@audiotechlabs4650]

Drones are definitely becoming the "high" for people. They go where no one could before. You seem to know a lot. What FUN! Thankz

[@UncleDoug]

You're welcome, ATL :)

[@silasfatchett5693]

An appropriately sized resistor between the rectifier and the reservoir (first filter) cap will result in 'sag'.

[@etheroar6312]

Uncle Doug, so far this is the best explanation I've ever heard. Thank you, Chuck

[@marviosantos]

+Ether Oar Yes to this! I had a good idea about transformers and retification, but after watching this series I now KNOW exactly what each is doing! Marvelous job as usual uncle Doug!

[@jk-76]

one day I am going to sit down and really learn. Fascinating

[@UncleDoug]

+anthony gabaldon It is fascinating, Anthony. Don't wait.......start tomorrow. You'll be glad you did.

[@jk-76]

+Uncle Doug once I can...

[@johncunningham5435]

Again; a great way of showing various choices when considering a power supply.

[@UncleDoug]

+John Cunningham Thanks, John. Speaking of choices, I just uploaded a video that will assist in selecting the proper high-voltage rating in a power transformer.

[@Modwiz125]

Video after video in a series is helping me learn new concepts. I will continue and repeat until how a signal moves from input to speaker is understood. Getting there. Thank you very much.

[@UncleDoug]

You're welcome, MW

[@donaldfilbert4832]

Excellent - very demonstrative video on power supplies. I had previously known of both the full wave and the full wave bridge rectifiers - but had never really reflected on the key differences between them as you so aptly illuminated them !! I really love the way you highlight key points and relevant techical details in your videos - as well as the associated terminology. Thanks for all the videos Uncle Doug !! P.S. - I'd love to see a video of you and Rusty "racing" out to the workshop - smile !!

[@UncleDoug]

+Donald Filbert You're welcome, Donald. Rusty and I (rested up from a recent race to the workshop) really appreciate your comments and input :)

[@sunnysart7913]

I'm so excited ! After watching your Power Supply series I was able to visually trace and identify all the components in my amps rectifier circuit. I have a full wave bridge. Doug, you rock ! Thanx

[@UncleDoug]

That's great news, SS. I'm glad you were able to use the information in the video for a better understanding of your amp circuit.

[@bullthrush]

The hand acting make up still got a chuckle. :)) I'm still happy with my bridge rectified 5F1, one less tube to worry about.You're copter is very impressive. I'd love to see some aerial photos of the Franklin Mountains and the city, just yesterday I was looking at slides from 1963-'65 when we lived there.

[@UncleDoug]

+bullthrush Thanks so much, Andrew. I concur with the benefit of simplicity provided by SS rectification. I do indeed have some exceptional video of the surrounding mountains that I may include. I just wanted to see if the viewers were at all interested before inflicting another "hobby" on them :)

[@td7456]

Another great video Uncle Doug, just like they taught us in tech school! Only our teachers did not make the ultimate sacrifice of decorations on their digits....The drone is fantastic! Can't wait to see some of your videos!

[@UncleDoug]

+Tim Dockery Thanks, Tim. I am always willing to suffer for the good of the viewers :) Glad you liked the drone. I'll try to work it into the videos from time to time.

[@DennisMurphey]

Again fabulous lecture and demo. Wow! I am gonna built that test this weekend. Don't have a Variac yet but working on it. Great stuff, Dennis

[@UncleDoug]

Thanks, Dennis. Glad you enjoyed the video.

[@AndyWragg]

Another bombproof explanation Uncle Doug. And I have some news of my own. I picked up a variac and some more test gear last night courtesy of a good friend. I also have access to his supply of vintage parts just as soon as I can clear our my garage/workshop.

[@UncleDoug]

+Andy Wragg Thanks, Andy. Congratulations !! That's great news. I really think that the best way to learn about amp circuitry is to get the proper equipment and then perform experiments, much like I do in the videos, to investigate different principles. An oscilloscope is a nice addition if you want to see the waveforms.......which often clarifies things.

[@tobortine]

Another excellent episode, thank you. Looking forward to the next part.

[@UncleDoug]

+tobortine You're welcome, T. Glad you liked it :)

[@cassvirgillo3395]

Hey Uncle Doug, Rusty & Crew, Very good explanation of the FWBR. Your graphic's are excellent, as they look hand drawn, very talented. I am probably your biggest fan in, what is now, Sunny Oregon. I'll take the Winter's, for the Summer's. I meant to mention, I saw a heard of Roosevelt cow Elk on may 1st, a little late for them this year. They are quite migratory and come around periodically, always nice. Excellent series on rectification, look forward to more. You really must have been an excellent teacher, because I am learning so much. Awesome Drone, nice Gimble, mass talented individual. I hope doing good & having fun. Peace & Happiness from Oregon, C.

[@UncleDoug]

+Cass Virgillo Thanks for your very nice comments, Cass. Rusty and I really appreciate them and wish you the very best that Oregon can provide :)

[@PrinceOfBodom]

The first second i saw your quadrocopter i thought: you should put a camera on it! Of course you already did. I am really looking forward to see some flying clips! Also the video was very interesting and gave a lot of answers to me.

[@UncleDoug]

+PrinceOfBodom Thanks, PoB. We're glad both topics were of interest :)

[@GLuft3]

Always with the negative waves, Moriarty. Always with the negative waves!!

[@UncleDoug]

Not sure I comprehend, thanks for your input, George.

[@GLuft3]

@@UncleDoug it was a reference to the movie Kelly’s Heroes.

[@UncleDoug]

@@GLuft3 I'm sorry I missed it, George. kzbin.info/www/bejne/jqrLXn2mjMl6o7M

[@MichaelLloyd]

Great series!

[@UncleDoug]

+Michael Lloyd Thanks, Michael :)

[@kloner]

Thanks. I can't wait until we get to the tone stack. Also, I was impressed with Jack's control. I know he wanted to chew on a propeller.

[@UncleDoug]

+kloner You're welcome, K. I have already posted videos providing a detailed overview of Tone Stacks. Please see my video list and check them out. By coincidence, Jack has indeed chewed on some propellers, forcing me to keep all my quadcopters behind a closed door for safety.

[@kloner]

I found them. Wonderful! Perfectly explained the tone knob sounds of my Victorilux vs. my 1970 SuperLead.

[@UncleDoug]

Thanks, K.....glad the videos were helpful :)

[@otteronbass]

doug, you're on fire releasing these. love 'em!

[@UncleDoug]

+otteronbass Thanks, Otter :) The weather lately has been real windy, so Rusty and I have been staying in the workshop.....makin' videos.

[@rubber20021]

I do agree!

[@tonymanns8249]

Great video Doug! As usual your videos are informative and entertaining. I find it interesting that you use "conventional current flow" to explain current flow. Not usual in electronics but very usual in electrical instruction. As you surely know, it doesn't make any difference, positive to negative, or negative to positive. Just an observation of mine. :)

[@SkyscraperGuitars]

Fantastic video as usual. I can't wait to see the drone footage. -Greg

[@UncleDoug]

+SkyScraper Guitars Thanks, Greg. Since there appears to be interest, I will definitely include some aerial footage in future videos.

[@saturn5tony]

Wow Doug, awesome explanation of the ps but even more, thumbs up on a very nice quad! I am sure Jack loves to be near it when you throttle up...hehe!

[@UncleDoug]

+saturn5tony Thanks, Tony. Yes indeed, Jack has no love for the drone, except for chewing on the propellers when I'm not around :(

[@tectalabyss]

Hi Doug. Thank you very much All the best from Molly and I. :)

[@UncleDoug]

+Bobby Tectalabyss You're welcome, Bobby, and warmest regards from Jack, Rusty, and your old Uncle.

[@montygore]

Love that rec tube sag.

[@UncleDoug]

Glad you liked it :)

[@lelandclayton5462]

Great video.

[@UncleDoug]

+Leland Clayton Thanks, Leland :)

[@Funnygalsproductions]

Custom drone ! Love that !

[@UncleDoug]

Thanks, HL :)

[@donaldfilbert4832]

Love the quadcopter !! That is also a passion of mine. Tho - I have not yet gone to aerial video and First Person View. I'd love to see some of your flying video footage !!! Also - you have built some seriously nice features into your copter - like the voltage monitor and feedback, and auto return to base capabilities !! I'd love to see a video on the build !! I know they can get very technical - and would love to see some of your technical references !!

[@UncleDoug]

+Donald Filbert Thanks, Donald. It's a very complex and challenging hobby, much like amplifiers :) I also have a FPV system for this quad which features OSD of telemetry data. I'll demo it in a future video.

[@joegile]

Excellent. Thanks UncleDoug

[@UncleDoug]

+joegile You're welcome, Joe :)

[@charleslaflamme2691]

Nice job! as usual.

[@UncleDoug]

+Charles Laflamme Thanks, Charles :)

[@predicadorhd]

Thanks a lot for the interesting video. Can you please incorporate a filtering/smoothing video to the series? And if you can, a basic notions of how to calculate the optimal circuit.

[@UncleDoug]

+juan rafael cubero rollán I have already posted a video on Filter Capacitors, Juan. Please see my video list. I am also considering the creation of a video explaining the substantial B+ voltage increases provided by the filter caps.

[@curtisprice9806]

EXCELLENT! 👍😀

[@UncleDoug]

Thanks, Curtis :)

[@NotMarkKnopfler]

Great video - you're really cookin' with these videos! If I ever get around to building an amp I'll probably use a simple bridge rectified power supply, or even a switch-mode power supply (though some of them can induce noise from the high-frequency switching). I stared somewhat slack-jawed at the copter. You've GOT to upload some camera footage from that bad boy!

[@UncleDoug]

+NotMarkKnopfler Thanks, NM :) It's been really windy around here, so Rusty and I have been seeking refuge in the work shop, grinding out videos and waiting for the weather to change. Since there seems to be some interest in the quad, I will indeed include some aerial video in future productions.

[@bertuspa3grn]

Hallo Good evening Thanks for the video Like the drone i think you have lots of fun whit it Bertus

[@UncleDoug]

+Bertus pa3grn You're welcome, Bertus. I do indeed enjoy building and flying the drones :)

[@budandbean1]

HI Uncle Doug, I enjoyed your video and really enjoyed the part about your quad, I'm also a drone guy but certainly not as advanced as you. I don't have a gimble and my flight computer doesn't do return to home. I'm working on long range FPV. I'd love to hear more sometime, it looks like you have a great handle on things.

[@UncleDoug]

+Buddy Martin Thanks, Buddy. I started out with a $75 basic quad and gradually worked my way up to designing and building my own.....which seems like a natural progression in most hobbies. Like amps, there is SO much to learn and SO many mistakes to be made (believe me, I know), but it's ultimately possible to work your way up to reasonable competence. I also developed an FPV system for this quad, including OSD of telemetry data, which I may demo in another video. More to come.

[@budandbean1]

+Uncle Doug , I don't want to ask a bunch of questions but I am curious where you get most of your information. Everything that I have gotten has been through KZbin's Painless360 channel. Any others you know of that have a lot of info? Thanks!

[@UncleDoug]

A lot is through personal experimentation, but the P360 channel is my favorite source of accurate info also. His videos are superb. I generally do Google searches and then weed through the junk, which comprises about 80% of the so-called "info" I see.

[@budandbean1]

Thank you!

[@BrianClem]

Expert at tube amps and history, auto fabrication, flying drones.... Where you always this high level or did it accrue over time?

[@UncleDoug]

Just skills and knowedge I've accumulated over the many years I've been alive, Brian. Thanks :)

[@raymondbailey7045]

I will thanks

[@ildarmingazov5189]

Спасибо!

[@UncleDoug]

Добро пожаловать!

[@ThomasACarlos]

Thanks for the video. At 20:42, you install the 4.7K resistor "after the filter capacitor." Does that mean that you removed the 2K resistor and replaced it with the 4.7K resistor? I did not understand when you said "installing capacitors with internodal resistors. Can you please explain this? Thanks!!

[@UncleDoug]

After rectification the DC still has AC ripple and must be filtered by several RC (resistor and capacitor) pairs. In between each big filter capacitor is a resistor. Look at any Fender schematic and you will see this.

[@ThomasACarlos]

@@UncleDoug Got it. Now I know what you are referring too. It looks like the 4.7K would connect to the bridge, and the plus side of the Cap goes to the 4.7K. That is also the point where the load is connected. This is how power supplies are designed with a choke and multiple (+) dc points. So I would expect to see a voltage drop at that point. Thank you!

[@UncleDoug]

@@ThomasACarlos You're welcome, Thomas. Think of the DC power rail as a street with several intersections that have resistors to reduce traffic. Between each of the paired intersections is a side street (capacitor) to smooth down the ripple in the traffic (DC).

[@thorpejsf]

A point of clarification -- the reason you can't use vacuum rectifiers for full-wave bridge rectification is because the common double-diode tubes share a common cathode! I think you could do it if you had 4 separate single-diode tubes and 4 separate rectifier filament windings (or, if they were indirectly-heated, you could use a single filament winding).

[@UncleDoug]

Excellent point, Jason. Thanks for clarifying this issue. I have added a note to the video explaining this.

[@blueties1]

The peaks of the "Rippled" DC voltage are going to be the same as the peaks of the AC voltage applied to the bridge, less 2 diode forward voltage drops. That is the DC ripple peaks will be very nearly 460 volts. When you apply the filter capacitor it will fill in the gaps between the peaks, giving you a "Smooth" DC voltage of 460 volts, and not 325 VDC as you have shown. The rms value of the rippled DC is indeed 325 volts as shown, but with the energy stored in the filter capacitor, the smooth DC rises to ~460 volts (allowing for small losses). Your own demonstration illustrates this very point at 17:10 when the ~17 volt DC ripple peaks produce an rms voltage of ~12 volts, but when the capacitor is applied, the oscilloscope clearly shows a smooth 17-volts DC, equal to the ripple peak voltage. If you had measured this smooth DC voltage with your voltage meter it would have indicated ~17 VDC. In conclusion, your "Smooth +325 VDC" is wrong and quite misleading.

[@UncleDoug]

Thanks for your input, BT.

[@r.charbon2028]

Wow, great vidéo séries, thank you, I finaly understand ; )

[@UncleDoug]

You're welcome, RC :)

[@brandonjay1086]

Awesome videos. My only question.... After the signal is passed through the amp circuit, and makes its way back to the transformer, does it not try to make its way through the second diode of the opposite coil? And if it doesn’t, what prevents that? Hope I’m phrasing the question correctly...Thanks.

[@UncleDoug]

The AC music signal never returns to the power transformer, only the high voltage DC returns.

[@brandonjay1086]

Uncle Doug thank you. I’m studying these videos as much as I can in my spare time. Hoping to one day take some courses on basic electronics. I’d like to design boutique amps and effects pedals someday.

[@UncleDoug]

@@brandonjay1086 You're quite welcome, Brandon. Best of luck with your education and business plans.

[@timsterz1]

Uncle Doug, I'm having a bit of trouble understanding why the signal, on its return is "bumped" by the one diode which is facing in the same direction of passage as the other is not letting the signal pass. Does this mean that, once a diode has "Blocked" a signal, a returning signal cannot pass through it? I'm sorry if this is a dumb question, but I would not waste your time if I simply missed something. I hope you can make sense of my dilemma.

[@UncleDoug]

I think you should watch the video again and listen carefully to the explanation, Tim. It's the best I can offer.

[@rlamb51]

Novel Idea - using the polarized finger tips. :)

[@UncleDoug]

+Roger Lamb Thanks, Roger. We go to great lengths to provide high-quality visual learning aids for our viewers :) :)

[@steveone]

GDay Doug . Did you build that gimbal platform from scratch or adapt something to suit ?

[@UncleDoug]

+Steve Smith The blue parts were 3D printed, the motors came from RC Timer, and the Control Board came from Ebay. After assembly, I configured the board using BGC 2.2b2 for the Mobius-style camera (its reduced size and weight, compared to a GoPro, necessitated special settings). I have designed several different vibration-reduction mounts, but so far am getting a bit too much "jello" for my liking. The engineering, research, and development, however, are my favorite parts of the hobby.

[@steveone]

Wow , colour me impressed !

[@UncleDoug]

Thanks, Steve :)

[@bucyruserie1211]

Hi Uncle Doug, Rusty and Jack, ( did the birds union go on strike?).... This series is Great! I also think you did an outstanding job on the 57 Vibrolux.... The 10" Alnico sounds really good. It took me by surprise, I expected the tight/treble/shrill sound of a typical new speaker, but instead it was warm and loose right out of the box. I don't want to beat a dead horse, but I've been thinking about this since I first watched this video last month. I went to an auction last year with my Parents where they live in Delaware, and bid then won a box of old tubes (I was the only bidder :) So for $15.00 I got about 100 NOS RCA and maybe 70 other tubes of various makes. There are 3 each of the RCA red tubes 5690-5693, The 91-93's are 6SL7,6SN7, and 6SJ7 respectively. The 5690's as far as I can tell is it's own entity, having no standard counterpart. It is a rectifier tube with 2 cathodes, 2 plates and 2 heaters. Just wondering if you think a pair of these would be able to work for full-wave bridge bridge rectification? www.tubebooks.org/tubedata/hb-3/receiving-type_industrial_tubes/5690.PDF Thanks for taking the time to look if you do, Tom Oh yea, really curious as to how the B&K projector amp is going to come out.. Take care

[@UncleDoug]

Thanks, Tom. The birds have refused to renew their contract pending a cleaning of their cage, so it may take a while :) I too was impressed with the new Jensen speaker. It truly does sound good right out of the box.....which isn't common. If the rectifier tube you described truly contains two completely separate diodes, and the tech manual certainly says it does, then I would imagine that a pair of them could indeed form a FWBR. You should cook up an experiment to see how well they can accomplish this challenging task. Thanks for your input.

[@psu2xj]

Hi again Uncle Doug! Is there anything to watch for in buying a Variac? I've seen many different power and current ratings, and I'd imagine amp work doesn't require a very heavy unit. What would you recommend? Some are available as just the autotransformer itself (maybe $15), scavenged from old equipment. They'd need a housing built and leads made up, at least. Would that be a fun project, or better just to buy a complete one and save the headache?

[@UncleDoug]

+Sam Owens Greetings, Sam. Some Variacs are capable of boosting voltage, but mine is a fairly simple 0 to 130VAC unit with about an 8A output capability, which is probably more Amperage than you would ever need. I agree that building your own would be a fun project, and you would learn while doing it.

[@psu2xj]

Thank you! :)

[@Cablexman2k]

Hi Doug, enjoy your videos. I have to ask, will using full wave bridge vs center tapped change the capability of maximum current production from the power supply?

[@UncleDoug]

+James Brown A center-tapped secondary has twice as many windings as a non-CT transformer, but since only half of the windings are producing current at any one time, the number of functioning windings would be the same in both transformers......so I would say that the current production would be about equal.

[@Cablexman2k]

+Uncle Doug OK, I get your reasoning. But it is my understanding that, while the number of windings determines voltage step up/step down, the load would determine the current drawn. How much current could be drawn safely should be determined by the gauge of the winding. So, if a center tapped transformer winding is only in use half the time, shouldn't both windings be able at least theoretically safely deliver almost twice the current? Please correct me though if I'm wrong here, I don't have a lot of hands on experience yet, just some reading.

[@UncleDoug]

From a heat dissipation standpoint, having two alternating half-windings would probably be superior to a single winding, simply because of the increased mass of wire, so ultimately a CT PT could probably withstand a higher current output over a longer time.....but I'm not sure that that it would be double. As you say, the current capability is dictated by the wire gauge, which is (to the best of my limited knowledge) about the same in both PT's (I am going by observation, not precise measurement). The load (amp circuit resistance) would be the same on both so that's not an issue.

[@megwatts1903]

I've been watching these technical vids for some time now. Just one thing I'm not clear on: why does the load on the circuit affect the waveform (ripple)? Also, wouldn't the resistor you put in the circuit lower the voltage through the circuit?

[@UncleDoug]

I don't recall saying that load affects ripple, Meg, but this video was made several years ago and my memory isn't the best. All I can think if is that when an amplifier circuit is driven hard, current demands increase and stresses the rectification circuit. Yes, any resistor placed in a circuit through which current is flowing will cause a voltage drop across the resistor and reduce the amount of current that can flow within the circuit.

[@silasfatchett7380]

Between each pulse of current from the rectifier the capacitor discharges supplying current to the load, so that the voltage at its positive terminal falls until the next pulse of current arrives to charge it up again. You can see this happening in the oscilloscope screenshot at 19:56 in the video. If the capacitor is required to supply more current the voltage falls further between each pulse resulting in more ripple.

[@daleburrell6273]

22:36...although I have no personal experience with vacuum tube rectifiers- I'm pretty sure that the voltage drop(s) across vacuum tube rectifiers is a lot higher than the .7 volt drop(s) across the silicon diode rectifiers.

[@UncleDoug]

Yes, it is.....and the figure varies depending on what rectifier tube is used.

[@daleburrell6273]

@@UncleDoug ...I vaguely remember that the old mercury-vapor rectifier tubes had a voltage drop of 15 volts(?)

[@hamedkhalilian6882]

dear uncle, if the full wave diode and full wave bridge rectifier do the job, why we use tube rectifier instead of two diodes? for example, I'm building a 5e3 amp now and I'm going to use a diode rectifier instead of 5y3 tube. some says I can use full wave diode rectifier, but you cannot use a bridge, and some says I cannot use any of them but tube. what's your suggestion and advice? what's right and what's wrong?

[@UncleDoug]

There is no right or wrong, Hamed, you simply use the method you prefer and can afford. Tube rectification offers a vintage-sounding effect called "sag" that many people really like. Diodes are cheap and efficient. You can use a FWBR, but you need a power transformer that is compatible.

[@raymondbailey7045]

Uncle Doug your videos are great I've learned so much from them. I was wondering if you can do the next circuit stage after the rectification stage and explain even like the basic workings of a Fender champ. Thanks again Ray PS say hi to Rusty and Jack.

[@UncleDoug]

+Raymond Bailey Thanks, Raymond. Please check my video list and you will see a series on how tube amplifiers work......it is based on the Fender Champ. Also see my series on scratch-building a Fender Champ from scrap parts.

[@michaelkoch5613]

Thank you, Rusty & Jack, for yet another informative video, rich with knowledge. And, of course, a big thanks to Uncle Doug as well! I'm trying to get my head around the concept of the center-tapped secondary, regarding phase and ground. I.E., how does the grounded center-tap throw one half of the secondary coil out of phase with reference to the other? (As opposed to creating two AC waveforms of equal polarity, with the grounded center-tap having the opposite polarity. Which, of course, we know not to be the case.) Keep up the outstanding work! P.S. Ever consider combining the Old Technology with The New? Meaning, of course... tube-powered quad-copter!

[@UncleDoug]

You're welcome, Michael. I look at a center-tapped transformer winding, either in a power transformer or an output transformer, as if the two separate windings are mirror images of each other, with the center tap between them. It seems natural, therefore, that signals each produced would be mirror images of each other.....and they are, except we say that they are "180 degrees out of phase".

[@michaelkoch5613]

Uncle Doug Well put; thanks again!

[@silasfatchett5693]

180 deg. out of phase since the current in each winding is flowing in the opposite direction with respect to the grounded center tap.

[@IFoundMyUsername]

Where did you connect the negative of the scope probe?

[@UncleDoug]

Probably to the chassis of the amp.

[@AsaBay2]

Loving these videos! I apologize if you answered this somewhere else and I didn't see it yet, but how does one determine the value for the filter capacitor?

[@UncleDoug]

+Stratton Yatron You can perform your own experiments, as I am doing, or you can access some good advice in vintage tube manuals. Also, you can see what the manufacturers used in their power supplies.

[@tectalabyss]

Hi Doug. I would like very much to see the videos of you flying your drone. It looks awesome. Does your camera setup use servos to keep it steady ?. I have been thinking of getting one to do some experiments with voltage collection. I have just watched your video again has I had to many things going the first time. Has always I enjoyed and learned a lot. Thank you again. All my very best. Bobby & Molly :)

[@UncleDoug]

+Bobby Tectalabyss You're welcome, Bobby. The gimbal uses brushless motors and a dedicated computer-control board to maintain a precisely stable platform for the video camera. I will indeed include some aerial photography in future videos. Our best to you.

[@CIPHER7968]

Hi Uncle Doug.. been following this series with interest. I have a question though.. Marshall use bridge rectification but the secondary has a centre tap that is placed between two capacitors in series.. what does this achieve?

[@UncleDoug]

+CIPHER I would need a schematic to be sure, Cipher, but perhaps they use this to get a reduced-voltage output for biasing purposes.

[@CIPHER7968]

+Uncle Doug I think I have actually worked it out.. it's a voltage doubler that moonlights as a bridge rectifier! My PT puts out 170VAC either side, and yields a B+ of 470VDC thanks to this smart little network. It would be cool to hear a proper description of what is going on in one of your videos instead of my hobbyist level of understanding. It's a Marshall Super Lead 100w amplifier.

[@UncleDoug]

By coincidence, I am currently working on a video explaining how a Voltage Doubler works. It should be posted in the next day or two.

[@silasfatchett7380]

​@@CIPHER7968 Referring to the circuit at: el34world.com/charts/Schematics/files/Marshall/Marshall_100w.pdf Although it looks like a bridge rectifier (and could be a bridge rectifier package) it is acting as two full wave rectifiers. The two leftmost diodes are configured to allow the negative excursions of the AC current to pass, charging the bottom capacitor so that its negative terminal is at -235V with respect to the center tap, so that the center tap is at +235V with respect to ground. The two rightmost diodes are allowing the positive excursions of the AC current to pass, charging the top capacitor so that its positive terminal is at +235V with respect to the center tap. The voltage across the two capacitors in series, each charged to +235V is +470V.

[@geraldhinson]

One thing I found myself wondering about as I watched this (around 22:30 in) was what happens with the negative part of the signal? Based on your (excellent!) explanation I would assume that the 4 diodes prevent the negative circuit from flowing at all based on their arrangement. It looks to me like the negative part of the AC signal would always wind up in the bottom of the diode triangle unable to proceed further. Is this the case? I really enjoyed your cost-based explanation as to why most amps don't use this the full wave bridge rectification. I've wondered about that in the past. Do any of your videos explain the term RMS? This was my first encounter with the distinction between RMS and peak. Usually I just hear about AC and DC. Great video!

[@UncleDoug]

+Gerald Hinson I've wondered about the negative portion of the wave form also, Gerald. It's easy to imagine that it's simply blocked, like water that is held back by a half-closed faucet, but I don't think that's the case. Wikipedia says that "Full-wave rectification converts both polarities of the input waveform to pulsating DC (direct current)", which would indicate that the negative wave form is actually inverted and placed above the center line (i.e. it "becomes" positive), in between each pair of positive wave forms. This is still confusing to me, but I am accepting it for now.....until a better explanation comes along. Yes, I explain RMS in Part 1 of this video series, and in another video entitled RMS. Please check out my video list.

[@geraldhinson]

+Uncle Doug Hmmm. That's interesting. I wonder what would cause that to happen if so. Also, it seems like your oscilloscope would show something different (strength or size of the wave or something else maybe) if that was the case. But, it seemed like it did not from viewing it on the video. Now you have me even more curious! Maybe Rusty knows.

[@UncleDoug]

I've looked hard for a diagram or clear explanation, Gerald. If you can find one, please let me know. Meanwhile, as you noted, the oscilloscope (which never lies) shows no negative wave forms.....so they must be incorporated into the DC.

[@geraldhinson]

+Uncle Doug Will do! I love a challenge, especially a geek challenge. :)

[@UncleDoug]

Good luck :)

[@docalex0]

Please can I ask a question. If you are building an amplifier with full wave bridge rectification and you don't have the correct filter capacitor , can you use one with higher capacitance [ with correct voltage rating ]? Many thanks in advance . I love your videos

[@UncleDoug]

Electrolytic capacitors are not expensive, D0. Why not simply buy the right one? If you are unable to afford a few dollars for proper filter caps, then you can use ones with around 25% higher capacitance, but definitely not double or triple. Good luck.

[@docalex0]

Thanks. So far I be stuck to values but noticed upgrades for blues junior sometimes changed values. Once again thanks for your videos. I’m an avid fan since my semi retirement

[@UncleDoug]

@@docalex0 You're welcome, D0. Best of luck with your projects.

[@michaelmcevoy4551]

hi great to see team Doug back on line.can I ask if it would be ok to record some of your videos for my own personal use.

[@UncleDoug]

+Michael McEvoy Thanks, Michael. You are welcome to record my videos for personal use :)

[@jimjewell2151]

so... if you already HAVE a 650VAC w a center tap on the 2ndary of your transformer, can you just run the amp off 1 "leg" ? from one side to the center tap? theres 325v there... just tie off the unused "leg?

[@UncleDoug]

You could do this, but you would have to use a full wave bridge rectifier because there would be no center tap for the half winding you are using. Also, the current capability of such an arrangement would be half of what it would be when using the full winding.

[@iroffman]

Would it be too complicated to add two diodes to a tube rectifier circuit and convert it to full wave (bridge)? Would the smoother current be more gentle with older devices?

[@UncleDoug]

A tube rectifier is full wave rectification, Kort. No need to add anything.

[@iroffman]

@@UncleDoug I left out the word Bridge. Sorry. I was thinking about a way to extend the life of older circuits but now I'm wondering if that would mess with their tone character.

[@UncleDoug]

@@iroffman You can't simply add diodes to an existing circuit to make it a FWBR, Kort. You would also have to change the power transformer. Also, there is no inherent benefit to FWBR, so the conversion is without cause or benefit. Thanks, however, for thinking about circuits and their properties.

[@iroffman]

@@UncleDoug I didn't think long enough. It was a half-baked idea. Thanks for your patience and inspiration. Cheers!

[@UncleDoug]

@@iroffman No problem, Kort. You were thinking......which is never half-baked.

[@scottjohnson7774]

maybe I missed something but if I recall correctly shouldn't your AC into the bridge be multiplied by 1.4 to get your filtered DC output?

[@UncleDoug]

+Bryan Sullivan Greetings, Bryan. Yes, the 14.08VAC RMS AC into the bridge was multiplied by 1.414 to get 19.9VAC peak input. The oscilloscope verified this voltage as well as a virtually identical filtered peak DC output.

[@scottjohnson7774]

+Uncle Doug does tube rectifier diodes exhibit the same voltage gain as silicon diodes?

[@kardRatzinger]

+Bryan Sullivan Vacuum rectifiers have much higher (and load-dependant) voltage drop. Please remember that the "voltage gain", if you want to call it that, is a result of the filtering cap, not the rectifier.

[@UncleDoug]

I agree, Kard. The diodes themselves cannot create an output that exceeds their input. Indeed, the output is actually a bit lower.....more so with tube rectification (as you stated). I intend to address this issue in a companion video to Part 2 & 3, which will seek to explain why the post-smoothed output in a functioning high-voltage amp circuit is significantly higher than the PT secondary input to the rectifier. Hopefully, this will also address Bryan's concerns.

[@supyrow]

Uncle Doug, letting Rusty paint your fingernails with sharpie.... priceless! :) Very good! 73

[@UncleDoug]

+su pyrow Yes, Rusty is a budding makeup artist and I sometimes let him practice on me :)

[@supyrow]

very clever idea regarding that BTW! never seen that before! 73!

[@Dutchamp]

Nice teaching Doug. Always laughably with your animals as a pauze in the video. I have a question : My tube amp 6550 pp still has some 50hz hum is it correct to add a wirewound 100ohm potentional meter 4watts between the 6,3v fillement wires at the transformer ofcourse on 6,3vac now I have earthed one of the 6,3vac to ground. Is 100ohm 4watt efficient?

[@UncleDoug]

Glad you enjoy the videos, WW. Connect the 6.3VAC wires to the outer lugs of the pot and ground the wiper, then adjust to balance and eliminate hum. Nothing will help if one of the 6.3VAC leads is grounded. They should both be ungrounded, twisted, and connected to the filament lugs on each tube socket.

[@Dutchamp]

@@UncleDoug yes understude Thx but 100ohm at 4watts is save enough? Wires are twisted and away from signal ac

[@UncleDoug]

@@Dutchamp The current flow through the resistor is negligible. I would think 4W was more than enough.

[@gardengnome4208]

Hello there Uncle Doug, I hope you are in good health when seeing this and hope you are having a good day, I found an old vacuum tube reel to reel player that was fully repaired except the old can filter capacitor, there was a date code that said 08/1970 it was a 50+50 uf 350v, the ESR was fine it didn't show any signs of dc leakage, I even did the capacitor in series with a speaker wire test and the music sounded fine on both sides of the cap. My question is do i let it stay, or do I throw it in a campfire for new year's :) (if my constant questions get annoying please tell me, I will stop)

[@UncleDoug]

I tend to leave fully functional capacitors in the circuit, GG; however, if the amplifier is going to be used a lot, especially for public performances, then you should probably replace the old electrolytics to ensure reliability.

[@gardengnome4208]

Thanks Uncle Doug! :)

[@CherryKirktown]

hey hey Uncle Doug. As a digital girl, I have loved watching your videos. This video addresses a question that I have had for some time, but doesn't quite answer my concern. You mentioned that most all vintage amps use tube rectification while modern amps use diode bridges. Ok, cool. It seems to me that the power supply section of an amp does not have any direct effect on the signal being amplified. And that only once the rectified and filtered power leaves the power supply stages does it begin to affect signal path. So, does it really matter, other than for aesthetic reasons, whether to use tube rectification or diodes? Thank you. Cherry K. Computer Engineer BTW, I have other dumb questions for a later time.

[@UncleDoug]

Not a dumb question, Cherry. One of the revered qualities of tube-rectified vintage amps is a tone condition called "sag", in which the power supply lags a bit behind the current demands placed upon it when the output tubes are driven hard and/or at high volumes. Diode rectification virtually eliminates this condition and many people find the result a bit too "sterile" for their tastes. Thanks for your input and nice comments.

[@jjheaphy]

Excellent. Thanks! Have you tried giving Jack a ride in the chopper?

[@UncleDoug]

You're welcome, John. Jack is quite wary of any flying devices since they tend to torment him in the house.

[@douglasRbrown]

Do a video on the build up of your quadcopter

[@UncleDoug]

It would deviate significantly from the topics that our viewers expect from our videos, Doug, but I'll keep your suggestion in mind for the future.

[@georgekrabs6948]

Please do a video on the drone.Now you've shown us the candy we want more.I'm sure you will get many viewers.Excellent series btw and love how messy wiring gets your appetite going for pasta.You've always got a beaut one liner that cracks me up.

[@liumander]

Very good one! Thx! We missed more appearances of Rusty and Jack in this one. I strongly suggest you to do a new KZbin channel called "The Rusty and Jack's Show" XD Good to know about ur drone avocation.

[@UncleDoug]

+Edu "Turupá" Sánchez Thanks, Edu. I like to offer a little change of pace every once in a while :)

[@Yupppi]

Two diodes in exchange for doubling the requirements of the power transformer? Count me in. Now if only there was a method where you could reverse the phase of the negative parts of the wave to add it up to the positive wave.

[@cassvirgillo3395]

Hey Uncle Doug & Rusty, I multiplied the 14.08 by 1.414 and indeed got 19.90912. Therefore, the .707 must be used for 1/2 wave rectification, is this correct? I will re-watch the 1/2 wave video. Great series. Be good, C.

[@UncleDoug]

+Cass Virgillo Actually, they are two ways to accomplish the same purpose. To change Peak to RMS you can either multiply by .707 or divide by 1.414. To change from RMS to Peak you can either divide by .707 or multiply by 1.414. The two numbers are reciprocals of each other. To prove it, multiply 19.90912 by .707 and see what you get.

[@krang07]

boy that drone thang looks top shelf. would love to see it follow you and looking down as you drive your truck around some trails or something cool. one youtuber did that and landed it on top of the car, then reached up and grabbed it. next thing you know they`ll be using these to do sky art with smoke trails or some shit.

[@UncleDoug]

+August Lyons Thanks, August. Yes, there is a flight mode called "Follow Me" in which the quad follows the transmitter, maintaining a constant distance. There are all sorts of other practical applications and the technology is advancing at a very rapid pace.

[@krang07]

+Uncle Doug Hey Doug, You could be the maker of the first flying tube amp. build like a tiny 3 amp unit and hook that up to an mp3 player and rock the skys in your neighborhood. :-) to add: I bet you've already thought of this huh. lol

[@UncleDoug]

What a great idea, August, and I could play the old Who album, "Quad"rophenia :)

[@megwatts1903]

Ok, sorry, I went back and watched the end again and grocked it. But when you put the inter-nodal resistor in the circuit, wouldn't that cause a slight voltage drop and wouldn't you have to design your power supply with that in mind?

[@UncleDoug]

Not at all, MW. If you notice, each node produces a progressively lower voltage that is suitable for the tube it feeds. Pre-amp tubes operate at much lower voltages than output tubes.

[@montygore]

WWow I like the drone. Are you using a buck on the motors?

[@UncleDoug]

I'm not familiar with that term, Monty.

[@Bigjoedo66]

Your are a great teacher, taking complex subjects and making them simple. With extraordinary finger puppetry . Thanks as alwaysPS. I don't think your assistants Rusty + Jack have a good work ethic. LOL

[@UncleDoug]

+Bigjoedo66 Thanks, Big Joe.....glad you enjoyed the "hand acting". Rusty and Jack are only playing their roles when the camera is on. When it's off, they are dynamos of creative energy......I swear ;)

[@davidlegault9745]

Great video again. Say hi to Rusty and Jack from Bear (in the photo)... Regards, Dave

[@UncleDoug]

+David Legault Thanks, David. We had a family member named Sparky, who looked a lot like Bear. He was one of our all-time favorites :) Regards to you all, too.

[@rheidtech]

awesome squared

[@UncleDoug]

+R HEIDEMAN Thanks to the third power :)

[@sixstringmarauder]

so is that what they call a Wien bridge, and why dosnt the voltage go through the lower diode? is it because the voltage is in phase with its own stream?

[@UncleDoug]

I'm not sure which power supply you are referring to, David, but it may well be the full-wave rectifier, which consists of four properly oriented diodes. The Wein Bridge consists of 4 resistors and 2 capacitors and is used to measure capacitance, not rectify AC.....so it really doesn't relate to the FWBR.

[@sixstringmarauder]

ok uncle doug i watched it again, at about 5;30 you stated because it bumped into it on the way out this diode is now closed, now i think i understand. thank you once again uncle Doug. I hope you don't mind me asking you questions that may seem a little stupid but I have no classical training in either math or electronics outside of high school and I am very eager to learn all you can teach.

[@UncleDoug]

You're welcome, David. Don't sell yourself short and don't hesitate to ask questions. As Rusty always says, "The only stupid question is the one that wasn't asked."

[@silasfatchett7380]

The bridge rectifier got its name because its schematic resembles that of a Wein bridge.

[@silasfatchett7380]

Oops! that should read 'WIEN bridge'!

[@mtabernig]

RMS in CC? Doug, I herd of RMS on AC bur how do you mean RMS on CC. Could you explain a bit more?

[@UncleDoug]

I'm not sure about the meaning of your question, MT. What do you mean by "RMS on CC"? What is "CC" ?

[@mtabernig]

continuous current= direct current@@UncleDoug

[@rayford21]

22:25 apx. 0.7v loss is true for germanium diodes but silicon diodes are much better with apx. 0.05v loss. Most power supplies use silicon diodes nowadays.

[@UncleDoug]

Thanks for the knowledgeable input, Rayford.

[@silasfatchett5693]

Silicon diodes have a forward voltage of around 0.65V, while germanium diode's forward voltage is around 0.25V.

[@dennislarson9560]

I have a power transformer from an Ampeg V-22 circuit. There are no center taps so I will need to use full wave bridge rectifier. What power rating will I need, 1A, 3A, 6A? And 1000 V PIV. What is PIV? Yes, I will become a patreon ?? pal soon.

[@UncleDoug]

You're correct about the need for a FWBR, Dennis. You must also be certain that your final DC voltage output is appropriate for your circuit......not much higher than needed. Since the current flow in the HV DC circuit is so low, depending on your output tubes and number of amplification stages, you can get by with a low-amperage FWBR, but I tend to go much higher than necessary, because they are inexpensive and to give a nice safety cushion. Either the 3A or 6A should work just fine. Think of PIV as an indication of the voltage which a diode, FWBR, or rectifier can tolerate before its ability to block either the positive or negative wave forms (depending on how it's wired in the circuit) starts to break down. 1000V PIV is about double what the rectifier will face and therefore is a good choice.

[@silasfatchett7380]

@@UncleDoug Just for completeness: PIV = Peak Inverse Voltage.

[@TheOriginalEviltech]

Use LEDs instead of the diodes and a slow motion camera to show them blinking while every pair is being used to rectify the current. 120 fps will in theory be enough...

[@UncleDoug]

+Eviltech That's a very interesting Idea, ET. It would be an excellent display. I'll keep it in mind.

[@patrickford9615]

I woke up the wife laughing out loud.

[@UncleDoug]

+Patrick Ford Tell her we're sorry, Patrick :) Seriously.....glad you enjoyed the video.

[@marcosorto7669]

where can I talk to you man!!

[@UncleDoug]

+Marco Sorto Either on my Facebook page: Uncle Doug's Vintage Amps or via personal message. Please keep in mind that I get a huge amount of correspondence, so my ability to provide lengthy answers or conversations is limited.

[@curtislowe4577]

"Used" electrons after running through the circuit of the powered device flow to the common negative circuit which is connected to the chassis ground. All of these discarded, low potential, used up and tossed away Direct Current electons must find their way back to the other lead of the xfmr. Better diagrams: www.circuitstoday.com/full-wave-bridge-rectifier Diodes allow current in one direction and block almost all of it in the other direction. From the diagrams referenced above the current returning from the circuit can't flow through D4 (1st half wave) or D3 (2nd half wave) to the same xfmr lead. Is this because of the higher voltage of the originating half wave? I.e. Does a diode use voltage to sort between two opposing current flows in an electrical analog of might makes right? If a higher voltage current reverse biases a diode an equal current in the opposite direction but at a lower potential cannot flip the diode to forward bias?

[@UncleDoug]

Unless the voltage rating of a diode is exceeded, it will only allow either positive or negative wave forms to pass, depending on its biasing (direction in the circuit). It has nothing to do with higher voltage being on one side or the other.

[@TheOriginalEviltech]

you'd need 3 tubes or at least 3 filament tube...

[@sworgan1]

Hi Doug, Good stuff as always Diodes can be interesting as we know, perhaps you could initiate the ampliholics on the wonderful world of Zeners sometime in the future and how they are sometimes used in amps. with regard to voltage doublers have you checked out the Australian site www.valveheaven.com and the marvelous Lamington Amp built on a cake tin its worth a look there are also other interesting projects that i am sure would peke your interest

[@UncleDoug]

+Steve Worgan Thanks, Steve. My experience with Zeners is limited to their voltage-regulation function in the charging circuit of British motorcycles.....but I have heard tales of their use for the same purpose in amplifier circuits. Thanks for the link, I will check it out and post it on my Facebook page: Uncle Doug's Vintage Amps for others to see.

[@painkillermc]

Hi Uncle Doug, thank you so much for your great, enjoyable, great structured, humorous and very much practically useful lessons! You must have been a great teacher - or are at least by now... One question here (for Rusty truly): you explain in your video, you mention about differences in the output voltage of trafos, that the AV to DC rectification will produce DC in the amount of AC peak voltage, since the capacitor fills the gap from top to top off the gap. Why does here DC equal to the trafos RMS Voltage then, rather than the peak Voltage? Is it a mistake, or did I get something wrong (more likely ;) ) Here it seems to be fine. The Smooth DC Voltage should be higher, peak voltage, like in this video of yours, right? kzbin.info/www/bejne/pKiXk4x4o6eSfZY

[@UncleDoug]

Thanks, PK. The rectified, smoothed DC should be at peak voltage. If I said anything else in an earlier video, it was incorrect and I apologize. Like you all, I am steadily learning as I proceed.

[@painkillermc]

Thanks for the reply, I got it sorted out. I have to emphasize, how much you help us out with your great effort. One thing I feel lost though (and maybe other viewers as well, so might be a good idea for a new project for Rusty, or Jack, if he is more anxious): How to pick/order the right parts? There are so many different choices in just in resistors (with more than 10 parameters), that even if I know, I need e.g. 100K +-10% and say 1/2W its hard to be sure, that what you order is right, since the other parameters confuse. So I would love to start to build - but I'm just stuck there. In former day I just would go to the electronic store and talk to the guy and he would know, what I need. Nowadays.. well.. we need you to help us out, I guess. You did mention to give some aid into this direction in your tremo-drive videos, but it kinda seems to got forgotten. Also a major problem this direction: I seem to find transformers 230V to 12 or 12,6 V, but not the other way round. Can I just "turn them around" and use the same transformer twice, wired mirrored? (e.g. in the tremolo-drive)

[@UncleDoug]

I buy all my components, except transformers, from Antique Electronic Supply. Their Internet store offers the exact resistors, caps, etc. that you need to build an amp.....and their descriptions are very helpful. With regard to the transformer, they don't really make 12.6V to 230V transformers, PK. As you suggest you simply use two of the 230V to 12.6V transformers and turn one around 180 degrees.

[@painkillermc]

Thank you.

[@rubber20021]

Kitty Jack needs some knorppel to nibble on! (German- sorry)

[@UncleDoug]

I believe that knorpel is cartilage or gristle, Harry. Jack prefers filet mignon with a fine Cabernet Sauvignon ;)