Power Supplies, Part 4: The Voltage Doubler

[@peteleoni9665]

I watched this, then immediately fixed a 2× 50L6 record player that had 2 selenium rectifiers understand completely why it began humming. World's greatest electronics teacher right here on KZbin. So grateful for you.

[@UncleDoug]

That's great news, Pete. Thanks !!

[@markcaruana7233]

Your educator skills are far beyond that of a teacher. You are a naturally born mentor and absolutely responsible for the majority of the knowledge and understanding I now possess for tube amps and complex control circuits circuits. As a note, I am a retired public educator for electrical technology and maintenance from which I learned and honed my instructional skills and mentored many high school and adult students into their own careers in the electrical field. After I retired I then took on a second career as a Nuclear Electrical Maintenance Training Specialist at a dual unit Nuclear plant in the NE from which I am now retired from. My knowledge of electrical theory is very strong and secure although my knowledge of vacuum tube and transistor amp circuits was in need of the guidance of a superior mentor. While searching and educating myself online, there you were and I haven't let up yet. You Uncle Doug are an amazing presenter of knowledge and the immense skills you possess. Since finding you I feel as though my knowledge acquisition is supercharged. THANK YOU for everything I am on a journey that lives in the fast lane. One last thing, I am also a musician and motor head. Been playing in bands for 40+ years and wrenching even longer. Built a couple sweet street rods over the years and still have an ongoing 44 year love affair with my 73 Big Block Z/28. Again thank You for everything. Mark

[@UncleDoug]

Wow.....thanks so much for all your very nice comments, Mark. We're really glad to hear that the videos have been helpful. Have you visited our second YT Channel: Uncle Doug's Hot Rod Garage? It's a perfect site for those who really love hot rods and mechanical work.

[@markcaruana7233]

Uncle Doug, I have indeed but only a couple times. I have been consumed with educating myself in analogue, (and some digital) electronics for the past several months. I have always enjoyed the field of electricity, enjoyed a career in the field not only doing but educating students and trainees. My career experiences where in residential to industrial design and construction, power distribution and system controls. Spent the final 16 years training and qualifying maintenance electricians at a Nuclear generation plant. This job also required troubleshooting and root cause failure analysis of some very complex systems. Turns out my strength is in print reading and troubleshooting. Still with all that, My career never required that Deep dive into the world of electronics. Plus I never had time to self study it. Heck, I worked ridiculously hours, raised a family, built two houses myself, always had muscle cars that I built and maintained completely as a hobby and continuously played guitar in bands which I still do. Had several tube amps since I was 17 and not once over all these years, repaired one. This has changed since studying under you and some other Einsteins on KZbin. I have troubleshot and successfully repaired several tube based amps a Hammond organ, a HiFi consoles and jukebox. Battery chargers galore although a microprocessor controlled SCR driven one has me out in left field. But, I will not let it get the best of me. On a final note I will be purchasing back my 1st tube amp. A Marshall JMP 50w head. Bought it used in 1972, sold it to a friend in 1980. Apparently a few wire biters worked on it over the years and it's now a cross between a Marshall, Fender and Vox. It is also not at all reliable and apparently sounds like dog excrement. I am going to restore it back to its original glory. It is however a plexi although until I get it on my bench, I am not sure what the original circuit was. So after this dissertation of a response, again, thank you for sharing your knowledge with Me and the world too. Now since I retired 2 years ago I am able to take advantage and enjoy learning the skills and specific tricks towards something I have wanted for many years. Looking forward to viewing your Hot Rod channel as well as I am not done there yet. Got my eye on a numbers matching 72 Vette in need of complete restoration. She spent her life in the SW FL sun, and has been under a tarp for the past 15 yrs. Oh, question, I am in the market for a used O-Scooe and noticed you use a Techtronics 220?. Good choice for an ole schooler like myself? Again thank you so much Be safe

[@hadireg]

The best professor ever! Thanks Uncle Doug!

[@UncleDoug]

Wow, thanks, Hadi :)

[@YeeThirty]

I love that you left in the error with the positive negative

[@UncleDoug]

Thanks, YT :)

[@OIE82]

I suspect that was for comic relief. Uncle Doug has a way of using laughter to keep his videos interesting and enjoyable. I had to back the video up 30 seconds to hear what I missed after that sigh! 😊

[@dkysimcox5662]

I have learned more, watching a few of your videos than I learned over the past 3 years combined! Thanks!

[@UncleDoug]

You're welcome, Riloh. We're glad the videos are informative :)

[@JoaoMartinsguitar]

Has anyone already said that you have a supperb diction?? Your english is very easy to understand even for me and I am not a native english speaker. We in the third world feel gratefull when you bring saving money solutions like this one.

[@UncleDoug]

+Joao Martins Thanks so much, Joao. I try to speak as clearly as possible, since I really hate it when people mumble :) Glad you liked the video and its economical alternative to the purchase of an expensive power transformer.

[@ryan98408]

Hi Uncle Doug, I'm a huge fan! I've since employed this method in a (dual) Altec 1566A mic preamp clone, which was on the Ricktone website. I also built a Trem-O-Drive into a large guitar pedal. Many thanks for your expertise! Your videos have been and continue to be an invaluable resource and reference.

[@UncleDoug]

Greetings, Ryan, and welcome to our channel. Thanks for your nice comments :)

[@budandbean1]

Uncle Doug, this has been a really fine group of videos about Power Supplies, transformers, and rectifiers, better than any class or course or general study that I've done. You really did good! Buddy

[@UncleDoug]

+Buddy Martin Wow, high praise indeed, Buddy. Thanks !!

[@jimhart6867]

thank you uncle Doug, your videos are the best, best speaking, best demos, best pets always ready and willing to help you

[@UncleDoug]

Thanks so much, Jim.

[@haroldhayesiii5846]

Blathering, especially yours, is cherished and gratefully accepted. Blithering, from others on subjects like high voltage is not. Thanks again, can't wait for the next installment!

[@UncleDoug]

+Harold Hayes III You're welcome, HH, and thanks for the kind words of support :)

[@donniebrite9170]

I am a commercial electrician and I hate trying to read schematics I am a visual learner I appreciate you going out to the workshop and putting it into action I just learned something new, this isn't learning for work though what I'm trying to do is hook up a couple transformers in series from the secondary so I can get a stepped-up primary to use as a AC stick welder because I've been needing one desperately

[@UncleDoug]

I hope you can apply the principles in the video to your application, Donnie, but the current demands of an arc welder are much, much higher than any tube amp circuit. You will have to do more research on sites dedicated to arc welding circuits. Good luck.

[@johnsalaman503]

I am going to need a 12 step program to get off these lessons..nah..these are great..very addicting..im loving every one..cheers

[@UncleDoug]

It's a good addiction, John, unlike most :)

[@cass2771]

Still getting value out of these in 2018! I’ve just reviewed Power Supplies Parts 1-4. Thank you again, UD.

[@UncleDoug]

You're welcome, Cass. It's like a convenient library that you can visit any time :)

[@mitchellpurelife]

Thank you Doug! Excellent video and explanation. You really make this easy to understand! So useful.

[@UncleDoug]

You're welcome, Mitch. Glad the video was helpful :)

[@audiotechlabs4650]

After reviewing your past videos, which in my opinion, brilliant, I would like to request a topic of great interest.The in-dept explanation of the output section of a double ended guitar amp. You have explained how to bias the output tubes and a further look at the circuit components before and after the output tubes and their function. If you have already posted such a video, I could not find it. You are the #1 person to do this kind of analysis. Thank you for your sharing. Thankz

[@UncleDoug]

+Audio Tech Labs Thanks so much, ATL. I believe that my Output Transformer video will address your question. In it, I discuss the relationship between the output tubes and the OPT in a push-pull relationship. I hope it is adequate.

[@UpcycleElectronics]

* Voltage Doubler Note*: If you keep the 4 diodes from the full bridge rectifier, all you need to do is add a switch and an extra filter capacitor to make a voltage doubler. The capacitors are connected in series between the rectified positive and negative rails. One side of the switch connects to one of the AC secondary terminals of the transformer. The other side of the switch connects at the center point between the two capacitors. When the switch is closed the voltage is doubled. Alternatively, if the switch is closed and the center point of the capacitors is connected to the load, this will create a dual polarity supply from a secondary without a center tap. I haven't played with the dual polarity configuration yet but I believe the ESR of the caps can become problematic in this configuration when loaded. Thanks for the upload :)

[@UncleDoug]

An interesting idea, UE. Thanks for your input :)

[@pacerodi]

I`ve seen someone playing with this circuit on a SMPS, but unfortunately, he didn`t show what happens to the amperage.

[@rich1051414]

There is a reason 'audio' grade capacitors have ultra low ESR.

[@chrisreynolds6331]

I made an isolation transformer for my workshop only yesterday using a couple of old hi-fi power transformers back to back. Works great.

[@UncleDoug]

That's good to hear, Chris.

[@youme112233]

Hi U D , I love your straight forward explanations . I wish all people in the world could get along as well as your Voltage Doubler does .

[@UncleDoug]

Thanks, Herg. All hail the voltage doubler :)

[@skycarl]

That was a excellent explanation of a voltage doubler. Read about them but never put one together on the bench. Will have to do that for some fun. Thanks as always. Kudos to Rusty on his math exam. A student. Carl

[@UncleDoug]

+skycarl You're welcome, Carl. I'd forgotten how much fun it is to perform experiments in the workshop. Seeing is always better than just hearing about something :)

[@sootikins]

+Uncle Doug I agree with Carl. That was the clearest explanation of a doubler that I have ever watched or read. Thanks!

[@UncleDoug]

You're welcome, Sooti. Rusty and I really appreciate your kind words :)

[@davidhendrox]

This was a life saver for me. You showed a very convenient way sir. Thank you

[@UncleDoug]

My pleasure, David.

[@hernancoronel]

Hey Uncle, thank you very much for your excellent and very clear videos with clear explanations for all of us to understand! Keep up the great content!

[@UncleDoug]

It's our pleasure, HC. We will :)

[@hernancoronel]

Uncle Doug I am looking for part 5 and can’t find it. Is it done or is it just me being dumb? Thanks!

[@DaveHilts]

wonderful concept and very useful!! Rusty once again shows his street smarts. Thanks UD!

[@UncleDoug]

+Dave Hilts You're welcome, Dave. We appreciate your nice comments :)

[@stefanvaneylen9488]

Fantastic Uncle Doug. Before this vid i couldn't understand my measurements on the power supply of my fender champ 12. Turns out that its a voltage doubler. I fully understand now my measurements and how it works.

[@UncleDoug]

It's great to hear that the video was helpful, Stefan.

[@garyeggleton1142]

I am waiting for next video, because I so want to build that tremolo, I learn so much from these videos

[@UncleDoug]

+Gary Eggleton That's great to hear, Gary. I think you will really like the project.....so stay tuned :)

[@JuanLega]

You explain everything so well it makes it simple. Thanks for sharing your knowledge.

[@UncleDoug]

Thanks so much, Juan. It's a real pleasure.

[@Nmojo]

I looked almost all of your videos . thank you very much Uncle Doug!

[@UncleDoug]

+Paris Minton You're welcome, Paris.....your eyes must be really tired :) Thanks for watching :) :)

[@Nmojo]

+Uncle Doug )) very informative and interesting

[@cassvirgillo3395]

Hi Uncle Doug & Rusty, Very informative power supply series, great explanations and demo's. Look forward to next part. You are the tops in Amps. I hope all doing well. A really great channel you have, learning a lot. Take care, C.

[@UncleDoug]

+Cass Virgillo Thanks, Cass......glad you enjoyed the video and are learning a lot :)

[@rsdmag]

Fantastic explanation of a concept that I never really fully understood. I have a 70VAC transformer I was wondering what to do with, now I know how to calculate what I can do with it. Thank you!

[@UncleDoug]

+Dan K You're welcome, Dan. Best of luck with your project.

[@eugenepohjola258]

Howdy. Really nice walk-through. My experiences: My location is Finland, Europe. The mains voltage is 230 V 50 Hz. In my 4 x EL34 PA I use a 230 V / 115 V 350 VA transformer. With a tripler I get abnout 500 V anode voltage running idle and about 460 V at full power. I made sure the item complies with Protective Separation. Voltage multiplying is usable up to maybe 4 or 5 times. No more, because as the voltage climbs, so will the impedance do squared. For filaments I use a separate 12 V 50 VA transformer. This also powers another tripler circuit for biasing the tubes. I use individual fuses for both transformers. This way there will be complete overcurrent protection. The transformer is a SELV item. A hybrid transformer will not provide full overcurrent protection in case of a partial short in the filament circuitry. The 3 phase voltage here is 400 V 50 Hz between two phases. There are 400 V / 230 V transformers easily available intended for floating control voltages in 3 phase switchgear with no Neutral. I use a 450 VA piece connected backwards in my 4 x KT88 PA. Because the inherent loss compensation now works backwards I only get 395 V AC for the anodes. Full bridge rectification and filtering yields about 540 V running idle and just a little over 500 V at full power. Regards.

[@UncleDoug]

Thanks for sharing your rather elaborate power supply considerations with us, Eugene.

[@PatrickInCayman]

Another great, crafty and very useful video!

[@UncleDoug]

Glad you enjoyed it, Pappa.

[@MegaWimberly]

That was really cool! Can't wait for the term/overdrive unit!

[@UncleDoug]

+MegaWimberly Thanks, MW. Other than the portable Leslie unit and some electromechanical tremolos, I have never presented an effects build, so this will be something new and hopefully interesting......not to mention inexpensive.

[@shawnhale2631]

Been planning on a champ circuit recently! The transformers for the generic power/output have been really nicely priced, but this definitely allows me to use some of my spare 12v transformers for sure! However, I do want to get into adding some lower voltage IC preamp elements, and I'd love a video about how to convert those high B+ voltages into reasonable audio IC voltages, if you wouldn't mind! Love the stuff you do! Very palpable and understandable! keep doing what you're doing!

[@UncleDoug]

Thanks, Shawn. I deal strictly with vintage tube amps and circuits, so modifications for an IC pre-amp is not in my repertoire. Perhaps a Google search will turn up some helpful information. Good luck.

[@Modwiz125]

Please indulge me another comment. Love how your ideas have so much applicability to amp building concepts combining practicality of weight reduction without any compromises to tone. This is fun to learn too.

[@UncleDoug]

Thanks so much, Mod. Yes, I try to minimize size and heft when designing amps. To me, there is no benefit in lugging around a 90-pound behemoth if you can achieve the same power (especially when miked, if necessay) and tone with a 20-lb. gem :)

[@EzeeLinux]

Very much enjoying these videos. :)

[@UncleDoug]

+Joe Collins We're glad, Joe. Thanks for watching :)

[@johnsawyer455]

Here we have a rare look at Uncle Doug's fingers. Again, well done, sir. Thank you!

[@UncleDoug]

All those years in Hand Acting School certainly paid off ;)

[@rolandberendonck3900]

Very nice tutorial on voltage doubling! Thanks!

[@UncleDoug]

You're welcome, Roland.

[@tonysfun]

Love the + and - symbols on your fingertips/fingernails ! Very nice idea! Love your videos!

[@UncleDoug]

Thanks, Tony :)

[@TheRandomDave]

this was a great series of videos. thank you

[@UncleDoug]

Glad you liked them, Dave :)

[@virpz]

I can't resist, I just hit like on every video of yours ! Ty so much for the great work.

[@UncleDoug]

We like that, V......by all means don't resist :)

[@cawfeedawg]

im learning so much from this series... THanks Doug!

[@UncleDoug]

+Cawfee Dawg That's great news, CD. You're welcome :)

[@DennisMurphey]

OK working my through your awesome lectures and i have 2 old transformers. I think I will set them up ad you show and just do the math and hook up a scope and practice all this stuff. 300 VDC out is amazing. And then ad the bid cap to smooth it out. I am so excited thank You Doug. Hope the Hot Rods are still chugging along too. Dennis

[@UncleDoug]

Good luck with your project, Dennis. Be careful !!!!!

[@DennisMurphey]

It failed, I had wired the the transformers wrong. Will try again later. I gotten bitten a couple times and I think now I will be extremely cautious. Got some old boards to screw it all down to. D

[@pyroman6000]

Careful, Uncle Doug- if you keep this up, I might become edumucated... Great way to explain the theory here!

[@UncleDoug]

Thanks, Pyro.

[@richardhaneberg6278]

Love to watch your videos. First you deliver a lecture then a practical demonstration. That is the hallmark of an experienced educator. So I get a two fer when I watch, my interest in electronics and pedagogy are both covered. One question: why don't you use a breadboard for your demos?

[@UncleDoug]

Thanks so much, Richard. We're glad to hear that the videos are effective teaching tools. I have never used a breadboard. I can see their benefit, but since I generally experiment directly with existing amplifier circuits, mock-ups are not necessary.

[@tectalabyss]

Hi Doug. Very well explained has always. If you get the time I would very much like a series on Watt's,Amps,mA's and uA's Thank you for this great series. I am looking forward to your next video. All the very best. Bobby&Molly.

[@UncleDoug]

+Bobby Tectalabyss You're welcome, Bobby.....glad you liked it :)

[@SNORKYMEDIA]

I fondly remember visiting the local Radio Shack ( or Tandy as it was branded in the UK) for the electronic kits with the spring connectors

[@UncleDoug]

+SNORKYMEDIA Yes, they used to carry all sorts of great components, but sadly have slipped into virtual oblivion recently. I bought the two filament transformers from them many years ago for something like $5.99 and $8.99.

[@davkdavk]

Greetings from Australia! Keep up the good work mate, really enjoying these videos. Cheers, Dave

[@UncleDoug]

+davkdavk We will, Dave.....glad you enjoy the videos :)

[@kimahlmann6707]

Rusty is such a smart good lookin boy :P really like your stuff, waiting for the postman to give me my EL34 kit.. love to hear all your tips&trick

[@UncleDoug]

Rusty and I thank you for your kind words, Kim. We know the feeling of waiting for the postman.....who always seems to come very late in the day, if at all, whenever he is carrying precious parts we need desperately :)

[@BrianOfAteionas]

Very cool! It would be awesome to see some videos about output transformers as well. It seems to be an often overlooked aspect of tone, and expensive part of the amplifier.

[@UncleDoug]

+BrianOfAteionas You're in luck, Brian. I have posted a video on Output Transformers. Please check my video list.

[@JohnSmith-ir4re]

Thanks again Uncle Doug. Just Subscribed. Could you and Rusty please do a vid about using the oscilloscope to check audio signals, such as a sweep. Something simple for people like me.....

[@UncleDoug]

Thanks, John. I've been asked several times to do this, and I have included the oscilloscope in several of my videos....but so far, I have not made an video exclusively on the scope. I will keep this suggestion in mind.

[@3gdosrsfs]

Great vids Doug. Reminds me of when I used to know all of this stuff...and Rusty is a great feature! Good boy! Good Boy! Please give him an ear scratchin' for me!

[@UncleDoug]

Thanks, 3G. Rusty is indeed a great inspiration to us all :) I will

[@planespeaking]

Fantastic, de-mystifying videos, looking forward to the ongoing valve, inductor and output transformer circuit videos! (Hopefully!)

[@UncleDoug]

+robleake Thanks, Rob. I have already posted videos on all of those topics. Please check my video list :)

[@planespeaking]

Thanks, will watch!

[@ImTheReal]

Shared 😸! Really, we can be called amphollic or "amp addicted" Thank you for another great video master!

[@UncleDoug]

+Humberto Martins Ferreira Junior You're welcome, Humberto :)

[@saturn5tony]

Wow great review of voltage dubblers Doug, thanks 4 sharing, and Rusty must have taken intro to math when he was a puppy! Smart dog, but he knows we don't develop film anymore and does not care how much room you have left, also,a bright move. haha

[@UncleDoug]

+saturn5tony You're welcome, Tony. Glad you enjoyed it :)

[@davemassie3726]

THANKS UNCLE DOUG, EVERYTHING SEEMS TO BE TWICE AS GOOD!

[@UncleDoug]

You're welcome, Dave......that's how "doublers" work :) :)

[@lobodiablo9971]

I appreciate you Uncle Doug

[@UncleDoug]

That's good news, Lobo.....Thanks :)

[@MisterTalkingMachine]

I remember doing this kind of stuff when I was very young, actually did it the first time I got some spare tubes to play with. Actually remember the first tube which I used to experiment a lot as a kid was an EBC91 made by Phillips, which I still have, though it seems to be pretty much dead. Placed two trasformers back to back, though back then I didn't use a voltage doubler. I just rectified half of the wave, which gave me a cap with about 120 volts. It was enough for my first experiments with vacuum tubes. You can also feed the secondary of one with an oscillator driven by a 12V battery. You could power tubes with low voltage sources, not unlike old car radios did.

[@UncleDoug]

+MisterTalkingMachine It's good to hear that others get a kick out of experimentation, Mr. T. Thanks for your input.

[@thomaslines8489]

I miss your valued and informative videos. Please come back to us.

[@UncleDoug]

Sorry for the long delay in our return, Thomas. We appreciate your kind comments.

[@fightingzero]

Your videos rule. Thank you for making them. Also, am I the only one that yells "Hi Rusty!" When he pops on screen!? Lol cheers!

[@UncleDoug]

+fightingzero You're welcome, FZ. Probably not, since Rusty seems to have quite a fan base :)

[@mrmoon7484]

Superb video uncle!

[@UncleDoug]

Thanks, Mr. M :)

[@MarkErikEE]

I have a trove of ATX power supplies (transformer: 230v primary, 2x 5v and 2x 12v center tapped secondaries) laying around and I thought that if I connect the second transformer 5v secondary winding (ratio 1:46) to first transformer 12v secondary winding (ratio 1:19) then my voltage on the second transformer primary winding will be about 500 volts?

[@UncleDoug]

Yes, if you apply 12V to 1:46 transformer, the output should be around 552VAC.....with very little current capability.

[@williamnichols6253]

This is exactly what I needed! How do you determine the value of electrolytic capacitors for the voltage doubler assembly?

[@UncleDoug]

Filter cap values for the 1st (reservoir) cap are provided in Tube Handbooks. The values for the remaining caps are based on the tubes used, current flow, voltage, etc.

[@williamnichols6253]

@@UncleDoug Oh I see. So the caps that are replacing Diode's to make the voltage doubler should be sized the same as filter caps would?

[@UncleDoug]

@@williamnichols6253 If the AC supply is 120VAC, see if three 20uf @ 350VAC caps work.

[@williamnichols6253]

@@UncleDoug Thanks!!

[@bertuspa3grn]

again an educational video Thanks. Bertus

[@UncleDoug]

+Bertus pa3grn You're welcome, Bertus :)

[@SuperCarver2011]

Sorry to be so verbose here, Uncle Doug; but this circuit interests me quite a bit, since I used it in my own circuit designs over the years, using lower transistor voltages and transformer windings for transistor guitar power amps. In my case I used the 4 diodes in a full wave bridge configuration and massive power filter caps (4000 uf) to serve as the voltage/current source for the power transistors. However it was not configured as a voltage doubler supply but instead as a bi-polar supply, using the centre tap of the power transformer tied to chassis ground. At the junction of the two (stacked) power caps it was 0V (ground. The negative side of the diode bridge and the cap provided the Minus voltage (-40v) for the collectors of PNP power transistors, and the positive side of the diode bridge and the filter cap, provided a positive voltage(+40v)for the collectors of the NPN power transistors when referenced to the centre tapped ground. This type of power stage was labelled full complementary with the power signal taken between the emitters ( of the centre point of the O/P power transistor set) and ground.

[@UncleDoug]

Very interesting, SC. Thanks for your knowledgeable input.

[@dispersemedia]

Hi Uncle Doug! If caps block DC, how do they work and give 305vdc after the diodes at this part @10:00 ? Sorry for the ignorant question. I'm only a hack who have done only simple guitar pedals.

[@UncleDoug]

Watch and listen carefully to the video, DM. It is all explained quite thoroughly.

[@MrBrymstond]

All of the other videos on KZbin parrot or mimic what they seen they can't answer a simple question. Uncle Doug understands, he gets it.

[@UncleDoug]

Thanks so much, Mr. B. I hope we can continue to do so :)

[@markustak6652]

As always a great video! I was wondering whether this could also be applied to an unused 5V filament winding of a regular HV power transformer for tubes to obtain a separate 9V supply for effect pedals that consume 100-200mA. Can such current values be achieved by raising the capacities?

[@UncleDoug]

Since 5VAC windings of guitar amp power transformers are generally quite robust, i.e. in the 3A range, this winding would have no problem providing 9VDC power for pedals......but you would need to incorporate a well-regulated, rectified power supply to modify the 5VAC to 9VDC and keep it quite stable.

[@daleburrell6273]

6:34...another thing to remember, is once the rectifier tube filaments are connected to the 12 volt winding(s), the output on the right transformer is going to be even LOWER.

[@UncleDoug]

It's true that the HV of the PT is much higher without anything attached to the output wires. This is because of the inverse relationship between voltage and current. The moment that current can flow, the voltage drops considerably.

[@daleburrell6273]

@@UncleDoug Absolutely- and a major factor to keep in mind, is the "internal resistance" of the power supply...

[@dbingamon]

I came across some Stancor P-8364 transformer that have three secondaries each at 12V 0.5A. I was thinking that two secondaries on the first could be series wired making 24V and then fed into two secondaries on the second transformer in parallel for even current distribution. It might be enough to run a preamp without a voltage doubler. The dielectric strength si 1500VRMS.

[@UncleDoug]

This seems like a roundabout way to build an amp circuit, Daniel. Let us know how it turns out.

[@bookguitarguy]

Appreciate your videos very much, and I LOVE dogs. Have a cattledog mix myself named Yoda. I do have to say that I think your mistaken in your interpretation of dog behavior (at least in this case) however... I speak dog. :O) First (being an older dog, and rudely awakened from his nap), when he came over to please you, and you were asking him which he preferred (when what he really preferred was to be taking a nap, and being overweight didn't really need the biscuits), what he was saying was, "Dude, I'm not even awake yet, this is what you bothered me for??? Let me think for a minute and stop rushing me." Eventually after being pressured to make a decision, he went with the 1 1/2 biscuit option (not necessarily knowing whether he had to choose or not, since he probably figured he could eat the other biscuit later), mainly because being an old dog with old teeth (and being smart), he recognized that there was less chewing involved (since they were already broken). He's no dummy! Rusty looks pretty old here, and again I deeply love dogs, so I hope he's still with us. If he is, I respectfully *urge* you to buy him a bag of Missing Link food supplement ASAP and add to his food (it's a powder, just sprinkle on top), it's absolutely amazing... over 1,000 reviews on Amazon with a 4.7 star rating last time I checked. It will add to his quality and length of life, absolutely, and I have no financial connection to the company. I just love dogs, and older dogs need a boost (contains high quality nutrients not found even in good dog foods), so I feel an obligation to tell every dog owner I meet about it, if they have older (or sick) dogs. I'd recommend trying a 1 pound bag of Ultimate Hip and Joint formula, though the Senior formula would work also, very similar but a few different ingredients. You can get this on eBay for a little less if you look around, usually... and follow directions on the package, giving him a little less for a few days until he adjusts to it, then the regular amount (probably around one teaspoon/day for him or so). If you try it (and trust me, if you love your dog you'll be glad you did), make sure you get "Canine", they make it for cats, horses, and birds now also. Please try one bag (which will last about two months), and see if you don't see a change for the better in his over all well being, and anything he might be dealing with (including arthritis, it contains Omega 3 oils and other great ingredients). It can only help (and improves energy level, digestion, and skin and coat also)... and read some of the reviews if you have any doubts about it. Thanks again for the videos, and best wishes.

[@bookguitarguy]

Here's a link with reviews, and a pretty good price, also! eBay prices are usually similar to this, and Senior vs Hip and Joint formula is your call, you can read the ingredients of each online and see which you think is best for him. Again I truly hope he's still with you, I know this video was two years ago. He looks like part Australian cattle dog, but a great dog either way. :O) www.amazon.com/Missing-Link-Superfood-Supplement-Glucosamine/product-reviews/B000SSN04M/ref=cm_cr_dp_d_acr_sr?ie=UTF8&reviewerType=all_reviews

[@bookguitarguy]

This might be better for him since it's designed specifically for the needs of older dogs. If you click on "See full item description" there's a lot more info about it. Depending on where you live, local pet stores may also sell it--I believe PetSmart does. There's a 5 pound bag also, but it's supposed to be used within 90 days of opening, so unless someone has several dogs, they can't use it all in that time. Just a small 1 pound bag is easy, and keep in refrigerator after opening (ie, just follow instructions on package). Food in bowl--sprinkle Missing Link on top--done. Blessings. www.ebay.com/itm/Missing-Link-Ultimate-Canine-Senior-Health-Formula-1-lb/132330650927?epid=664069189&hash=item1ecf857d2f:g:VW8AAOSw4HVWDuhm

[@UncleDoug]

Thanks so much for your very kind and helpful advice, BG. Sadly, Rusty passed away several months ago, just shy of his 19th birthday, peacefully and at home with his family. He was a loyal friend and companion every day of that time and I still grieve his loss.

[@bookguitarguy]

Truly sorry to hear that... I know what that's like. Wow, 19 is an amazing age for a larger dog-WELL DONE. Obviously he was well-loved and cared for, and if you get another dog, you (and/or any other dog owners out there) will hopefully benefit from the information. It's amazing stuff, I should buy stock in the company. :O) Rusty was lucky to have you for all those years. All the best- Fred.

[@bookguitarguy]

Do you think Rusty was part Australian cattle dog?? He looks like it to me. My dog Yoda is 50% (his father is a pure blue heeler/Australlian cattle dog). This might cheer you up a bit, if you like slow motion dog action. Yoda is in white, and he eventually gets a takedown of the other dog three times his size. LOL. Hope you enjoy it. kzbin.info/www/bejne/qX-1n2l-qbl_mqs

[@johnruscigno5738]

I like the isolation concept using two transformers, you can experiment without tripping the breaker

[@UncleDoug]

Also, you can use a current limiter......see my video on how to make one.

[@grantfullen9559]

Thanks for these videos.

[@UncleDoug]

+Grant Fullen You're welcome, Grant.

[@lelandclayton5462]

Hey Uncle Doug. Great video as usual. I think I may know why the sine wave on the output was a bit flat. The term is called clipping. It's trying to suck out more current then the transformer can push out. Maybe a load can be added to the 12volt filament line to make the first transformer to produce more current so the second transformer can rob from it. Honestly I never tried this form of a voltage doubler so I might be wrong but from what I have read in text books on power supplies this sounds like the first transformer isn't pushing out enough current.

[@UncleDoug]

+Leland Clayton Thanks, Leland. I put the larger 3A transformer in the first position to avoid any problems with current starvation, but you may be right. I would have thought that the primary winding of the second transformer would be load enough to maintain the current level between them.

[@anotherOneMore7]

I wish youtube would create a search feature for comments so I could tell if you have answered questions already on a particular video. Is there any disadvantage to using the voltage doubler compared to using a larger single transformer?

[@UncleDoug]

Sadly, that is not possible since the comments are all posted on YT, and cannot be manipulated by me.....or anyone else except them. The voltage doubler is only useful in low-current circuits, since each time you double the voltage, you halve the current.

[@anotherOneMore7]

@@UncleDoug Thanks. I knew you personally could not make a search for comments feature, I just wish KZbin would add that feature.

[@ulisesaguilar4392]

thks a lot for the advice Mr doug

[@UncleDoug]

+Ulises Aguilar You're welcome, Ulises :)

[@SuperCarver2011]

Ebay is probably the best bet for surplus transformers as today, a lot of these old surplus shops in my area are out of business..rents and other operating costs are too expensive today for a surplus electronics shop to make any profits. Years ago, back in the 70s, that wasn't the case, and you could get a lot of surplus or even NOS at these stores at cut rate prices. I bought a lot of stuff at these stores including VTVM kits and nixie tubes. Radio Shack used to sell electronic bits and pieces and while they were convenient, they were expensive. They would package two resistors in blister pack and sell them for $1.99 or 10 of the same kind for $3.99...somebody was thinking that was a good business strategy for RS I never bought any parts from RS because to build from scratch, you would need many resistors, capacitors and other active components like transistors. To build even a simple electronic project like yours, it would cost 10 times more than if you bought it already made. No wonder they got out of the electronic component business years ago no serious experimenter could afford their prices.

[@UncleDoug]

....and it appears that Radio Shack is now struggling to find a niche in a rapidly evolving marketplace. My local outlet was recently shut down and there is now only one RS on my side of town. They seem to specialize in cell phones and have cut way back, to near zero, on their electronic components.

[@SuperCarver2011]

Wish RS a lot of luck in todays cell phone competitive market. The same thing happened in Canada a few years back with RS, they were bought out by Bell (Canada), after the RS chain went into receivership, and renamed as "The Source"..they also sold Bell cellphones exclusively as well as flat screen TVs, computer monitors and RC toys.,etc They had only a tiny alcove at that point for some common electronic components like LEDs, two types of small transistors, and mostly charger adapters and interface cords and stuff like that, but no more resistors or caps, and this was..probably repackaged old stock as well, to get rid of the surplus from RS. There was one in my neighbourhood for a while, but even after the takeover/resurrection, they seem to have vanished in most areas, as that store that I used to buy the odd electronic component when it was RS, has closed for about 2 years now for good.

[@UncleDoug]

They are slowly fading away in my area too. It's kind of a shame, because I liked having a component source nearby whenever I needed an item quickly.

[@ulisesaguilar4392]

very nice and explain video , Mr Doug , I will be waiting for video five ,a Question MR Doug , what were the diode size and cap if You can give the out Sir

[@UncleDoug]

+Ulises Aguilar The Trem-o-Drive circuit uses 1N4007 diodes, Ulises. The bridge caps are 10uf@250V. This is all stated on the schematic that you can download using the link in the video description.

[@paulkielt9301]

It's a great alternative to get rid of hum with cleaner DC at the end. Unfortunately you'll need some space on your chassis to install them.

[@UncleDoug]

Indeed, Paul. Thanks.

[@Xomby]

Heyo Doug! As always, still really enjoying your videos! How about tearing apart some old and unused transformer-based 12v wall-warts for their transformers? Super cheap and plentiful at the local thrift shops!

[@UncleDoug]

I have never considered that, XC, but I have a few in the workshop and may dissect one to see what's inside :)

[@Xomby]

Well I'm planning a 12ax7 or 12au7 preamp for a buddy's phono setup, so if I don't blow myself up I'll let you know how it goes. For now, on to that Vibrolux refurb Pt. 2! Beeeeaaauuutiful!

[@UncleDoug]

Thanks, XC, and best of luck with your project. Let us know how it turns out.

[@ulisesaguilar4392]

OK Doug I appreciate Your experience

[@UncleDoug]

+Ulises Aguilar Thanks, Ulises.

[@murratosmani6517]

Great, how Rusty mastered the quiz. My cats start eating before I'm able to explain the test... Somehow clever:)

[@UncleDoug]

+Murrat Osmani I'm not sure if he picked the 3/2 because it was MORE to eat, or because it had already been broken up and was EASIER to eat.....:)

[@murratosmani6517]

+Uncle Doug I had the same thoughts;)

[@dennislarson9560]

One more question Doug; It If use a 24 volt secondary with 5 amps to a 24 volt and 3 or 4 amp as a second transformer will I get enough total power to use a Harvard amp head? Yes, I will have to reduce the voltages to the filaments, that should not be a problem. I intend you use this amp as a keyboard amplifier.

[@UncleDoug]

I honestly don't understand the question, Dennis, or why you would even consider doing this. Sorry.

[@dennislarson9560]

@@UncleDoug: Wouldn't I have more (higher) voltages and amperes? As your video showed this voltage doubler will not provide enough power to drive a two tube amplifier.

[@UncleDoug]

@@dennislarson9560 Why not just provide a single adequate power transformer?

[@sinecure45]

Forgive me if this question has been answered elsewhere. I wonder if a similar doubling operation can be performed with 2 output transformers, such as one might find on an old stereo hifi? Thanks for a great exposition Uncle Doug.

[@UncleDoug]

You could try it, Jay, but two issues may arise: 1.) Is the current handling capability adequate? 2.) Where will you get your 6.3VAC or 12.6VAC filament voltage?

[@michaelmazzen]

That's one well behaved dog! Or you're feeding him way too much :-)) Anyways thanks for another great video Your stuff deserves a wider audience !!

[@UncleDoug]

+michaelmazzen Thanks, Michael. Actually, he eats very little, but I think the content of the food tends to be fattening. I will be changing his diet very soon.

[@hydorah]

Hey Uncle Doug! Happy New Year! Do you have a vid on how to make and use a capacitor discharger like yours?

[@UncleDoug]

Likewise, H. Yes, but it's included in one of my biasing videos......probably the one on DE biasing.

[@PrinceOfBodom]

I am curious how the tremolo-overdrive circuit will work. I looked at the schematic of the princeton and figured out, that the level of amplification in the powertubes is modulated by an ac-voltage, but i got no idea how to create this oscillation with a single triode. I guess it is filling and draining a capacitor? Also this voltage doubler circuit is very nice. Could it be used to create a envelope follower for an audio signal, for example to link the speed of the tremolo to the dynamics of the guitar?

[@UncleDoug]

+PrinceOfBodom I'm glad you're interested in the tremolo-overdrive circuit, PoB. Since it's inserted between the guitar and amp, like a pedal, it will provide a variable amount of boost to the input signal, allowing for overdriven tone at not-so-high volumes, and will allow a variable speed and amount of tremolo modulation to the input signal. Unlike any trem you may have ever seen, it acts on the first pre-amp tube rather than the output tubes. As far as the voltage doubler, I am not familiar with the application you mention. You will have to seek information elsewhere.....like the Internet. Good luck.

[@SuperCarver2011]

Connecting up the secondary of one 12 volt transformer to the 12 volt secondary of another will work as in your example BUT there are some hysterisis and laminate core losses as the winding wire guages were designed for more efficient current operation if the primary has the higher voltage applied to it,. Normally it would be a much thinner gauge of wire. So in reversing the winding functions, the voltages will not be the same as in a normal ac connection, but as long as the output ac voltage is not critical, it serves the purpose. The current requirements at the primary only serves to energize the laminated core magnetic field, which the secondary thicker guage winding is wound around in a conventionally wound transformer. The exception would be an auto transformer.

[@UncleDoug]

Again, very informative. Thanks.

[@olegmosk66]

Спасибо! Понятно даже без знания английского языка ,или я учу английский язык по вашим видео. Очень хорошее дело. Построил, с вашей помощью 5f1.ремонтирую ,,champ 12,,который имеет подобную схему power simple. Это видео очень помогло понять как это работает. Продожайте пожалуйста. Интесно как самому расчитать power simple имея трансформатора без имени. Привет с Украины

[@UncleDoug]

Пожалуйста. Мы рады вам понравилось это видео и извлекли уроки из предыдущих видео. Благодарим вас за ваши комментарии очень приятно. Удачи.

[@olegnesterov3467]

Thanks for idea, Uncle Doug. I made high gain preamp with 2 transformers and voltage doubler. It works perfect and very quiet. No hum. Should secondary transformer 12v CT be grounded?

[@UncleDoug]

According to the original schematic for the power supply, there is no need to ground the center-tap.

[@olegnesterov3467]

Uncle Doug Thank you, Uncle !!!!!!

[@GregsGarage]

I have a feeling Rusty knows you are filming and he likes to toy with you. LOL! Great video on power transformation. I still get stuck on sizing capacitors. I can understand the voltage part of them... Match it to the voltage it will be handling, but I don't understand how/why to choose larger or smaller uF capacities.

[@UncleDoug]

+Greg's Garage Thanks, Greg. I intend to post a series on capacitors in the future that, hopefully, will answer your question. In short, it depends on the current flow through the circuit, the maximum amount of ripple you anticipate, and the fact that larger caps take longer to charge and discharge.....and this rate must be suitable for the smoothing demands of the circuit.

[@GregsGarage]

I'll def be looking forward to that. Right there you answered what I need to look for and why. Thanks!

[@UncleDoug]

You're welcome, Greg :)

[@prophetsnake]

If one was to use 230V at the wall, down to 12 and back up to 230 (ish), a bridge would replace the doubler, as you have stated. But, would additional filtering be required in place of the two eliminated doubler caps? The application I'm thinking of here is the Ricktone TremODrive

[@UncleDoug]

I don't think so, PS, since the purpose of the doubling caps is doubling, not filtering, but the only way to know for sure is to build it and see. Let us know what you discover.

[@prophetsnake]

Thanks Doug. If I get a third, 'Tommy Gun' effect - bonus!

[@UncleDoug]

Good luck :)

[@prophetsnake]

Further news. Right, I've built a Rick-tone Tremodrive using two 230-12 transformers. Not owning an oscilloscope, I can't yet comment on the smoothness of the supply, but I can tell you that it's a wee bit high - about 302V without the tube and around 297 with. The unit doesn't work at all, but I don't think this problem is the issue. Of course, all of the pin values are crazy at the moment, so I will have to sort out the supply first, then see about the rest.

[@bullthrush]

Very neat! I'm excited (pun intended) to see the tremolo / OD, even though I have 4 ODs on my pedal board now. :))Is this the drive that appeared in the "Elvis amp" video? Rusty looked too sleepy to make snap decisions.

[@UncleDoug]

+bullthrush Thanks, Andrew. No, that was a different one, but I think you'll like this one too. It took him a while to remember his fraction lessons from puppy school.....but came through in the end :)

[@Jim5150jvc]

Thanks for the video, Uncle Doug! A question: I am building a Lectrolab R203 (the schematic is online). I don’t like the fact that the circuit for the fillaments is on the primary side of the PT, so I would like to have a separate isolation transformer, and am interested in applying the concepts of this video to save money. The circuit of the filaments are in series, and it goes: 130 ohm 5W resistor, the filament for the 35W4, the filament for the 50C5, the filament to the 12AU6, and finally back to the PT. If I make a voltage doubler as in this video as a separate transformer set for this filament circuit, what are the minimum current requirements the two transformers need? Can I get by on the 1 amp ones, or would I need to purchase a pair of 2A or 3A ones? Thanks!

[@UncleDoug]

I understand your concern with the series filament circuit, Jim. Since the primary AC is present throughout the circuit, the chance for shock exposure is much higher than with a regular amp. The solution is easy. Use the two transformers aligned as described in the video (120V:12V:12V:120V), with no doubler circuit. The output from the second transformer will provide the 120VAC that the circuit requires and you will actually have double isolation. Just be sure that your transformers can satisfy the current requirements of the circuit.....probably 1A will do.

[@Nirky]

Hey Uncle Doug I found a 115v to 115v isolation transformer that I'm going to use w/two diodes to make a doubler. My question is, the secondary has 3 wires; two red and one white called the "shield". What do I do with the white, if anything? Thanks!

[@UncleDoug]

I'm not sure why it's called "the shield", Nirk. You could simply tape the end of it and use the two red wires, and see if it works. Good luck.

[@Nirky]

@@UncleDoug Thanks for getting back to me. I checked and it's not part of the secondary winding. Perhaps it's something that's connected to ground, but I'll just shrink wrap it and forget it. Thanks again!

[@jjheaphy]

Wow! Very good. Rusty seems a little smarter than Jack....

[@UncleDoug]

Thanks, John. I just asked Jack and he insists that he is by far the smarter of the two....but you know how cats exaggerate :)

[@rheidtech]

awesome vid UD

[@UncleDoug]

Thanks, RH :)

[@RikMish]

Do the transformers require a center tap? What would happen if you did not have one? And would a virtual center tap work with a couple resistors or a humdinger?

[@UncleDoug]

Which center-tap are you referring to, RM? If it's for the high voltage output, then you need a CT for full-wave rectification. If there is no CT, you can use a full-wave bridge.

[@RikMish]

@@UncleDoug On the secondary 12v side. You mentioned at least one of the transformers should be center tapped. I have 2 120v-12v transformers but no center taps on either. So would 2 220ohm resistors to ground work as a tap for the heaters? And on the hv side I'll have the voltage doubler setup.

[@ralph9987]

another great video, thank you. btw, what voltage value did the 2 x 10uF caps have?

[@UncleDoug]

Thanks. To play it safe, 350VDC.

[@quest2718]

Very nice videos. I have one question . When you have two transformers head to head like that how does hysteresis reduce the output? I think it has something to with magnetic induction lagging behind the magnetizing force.

[@UncleDoug]

Thanks, Quest. I recall hearing the same statement many years ago, but wonder if it applied to two transformers operating secondary-to-primary rather than secondary-to-secondary, as they are in this instance. To be honest, Rusty and I lack the full understanding of hysteresis necessary to make such a determination, and would appreciate any input from more learned viewers.

[@quest2718]

I will ask around and do some research on it. I will try to get back to you on the subject. Thanks again.

[@UncleDoug]

You're welcome. Best of luck with your search.

[@TechTins_Projects]

Nice video Doug. How much current will the 12 volt taps take? Presumably they go to the cathodes?? Is that a lot of current through those 12 volt windings? Interesting mod.

[@TechTins_Projects]

Presumably you could not use any old 12 volt secondary. I suppose those special ones (filament transformers) use thicker copper in secondary windings? I am guessing here ha ha!

[@UncleDoug]

The 12V taps are used to provide filament voltage to the 12AX7, TT, which is only 150mA.

[@michaelteel4917]

I recently changed my Vox over EL84 from 6973 so I need to lower the plate voltage from the output Trans which is 460 v DC and I need to come down to about 350 v DC. Would a voltage divide using two resistors work with that high of voltage. Thanks . Love your videos and say hi to the crew.

[@UncleDoug]

Yes, you could experiment with resistor values to lower the plate voltage (and current), sort of like the voltage adjusting network in the -DC grid bias circuit in Fender amps.

[@michaelteel4917]

@@UncleDoug Thanks.