Power Transformers: Why The DC Output is Much Higher than the RMS Rating

Many people have discovered, often "the hard way", that the rectified and filtered DC output from a power transformer is much higher than its RMS AC output rating. For example, a PT rated at 400VAC RMS is actually capable of producing close to 560VDC. Granted, once current starts flowing through a functioning amplifier circuit, this value will decrease somewhat.....but it will always be much higher than the original RMS rating.
In this video I explain why this happens and what functional, in-circuit DC voltages you can expect based on 1.) The RMS rating of the PT 2.) The amount of current that will be flowing through the circuit 3.) The type of tube rectifier or diode rectification that is used.
In addition, at the end of the technical video, I have attached a 6 minute "Jeep Desert Tour" video that hopefully will be of interest.
Thanks for watching. Please subscribe, if you haven't already, to gain immediate access to 135+ similar amp, jukebox, and effects videos.

[@berniken6511]

Thanks for the jeep ride Uncle Doug, your a lucky man to have such a beautiful place on your doorstep................Berni

[@UncleDoug]

+berni ken You're welcome, Berni. I guess if I were born near the seashore or a lake, I'd be obsessed with aquatic hobbies, but we tend to make do with the hand we are dealt......and I really enjoy mine.

[@tbdalva]

What a treat, I laughed when you drove by the old couch and said "sweet".It's a shame people treat the dessert as a dump.

[@UncleDoug]

+tbdalva Amen, TB. I still can't imagine why someone who is too lazy to drive to a real dump, would instead drive to the top of a steep, sandy hill to unload his crappy junk furniture. "The folly of mankind never ceases to astound".

[@DaveHilts]

UD, I thank you again for a great educational experience on tube and ss rectification. The desert tour was wonderful and has led me to believe we must be part of the same soul group.

[@UncleDoug]

+Dave Hilts You're welcome, Dave.....glad you enjoyed the video. There is nothing like a trip to the wilderness to "cleanse the mind and sharpen the senses" :)

[@veganlion8662]

Lovely video, really liked the desert scenes at the end.

[@UncleDoug]

Thanks, VL. Glad you liked it :)

[@ElPasoTubeAmps]

Great video, Doug. I love the desert southwest too. I was out shooting .50 cal black power Wednesday evening in NM off Hwy 404 towards WSMR. Can't get enough of it.

[@UncleDoug]

+ElPaso TubeAmps Thanks so much, David. I think a double benefit is conveyed by any enjoyable hobby that requires venturing out into the wilderness. It gets us back in touch with the adventurous side of our personalities, which has been so scrupulously suppressed by society.

[@shaneeaston4027]

I enjoyed the tour. You are generous to make the effort to share your knowledge.

[@UncleDoug]

+Shane Easton Thanks, Shane.....glad you enjoyed it :)

[@thesillyhatday]

Even though I am familiar with the subject, this video series has been a good recap. Plus it's still satisfying to hear others share knowledge. With a great ending. I've been waiting to hear the jeep in action. Please keep making videos, this has become one of my favorite channels. Dan

[@UncleDoug]

+ubanoob Thanks, Dan.....glad you enjoyed both portions of the video :)

[@ronniepirtlejr2606]

Uncle Doug, that kind of looks like where I used to live at, in the Mojave Desert! outside of Barstow, CA., Hinkley,CA.or Needles, CA . Oh how I miss those long drives in the beautiful and mystical desert! Especially the gorgeous sunsets! Show them how beautiful they are Douge! :-)

[@UncleDoug]

The desert is indeed a very special place, Ronnie. I visit it often :)

[@davida1hiwaaynet]

You live in a beautiful part of the world! Thanks for the video hike in the desert - I have to make another trip Out West soon.

[@UncleDoug]

You're welcome, David. Thanks for joining us on this trek :)

[@saturn5tony]

So funny about the odd behavior of the 5Y3, wow very interesting.Thank you so much for such a cool view of the desert as well. It did seem so calm but yet a bit scary with what could have been snakes, lol. Very fun tour Doug.

[@UncleDoug]

+saturn5tony You're welcome, Tony. Yes, the good old 5Y3 is not very efficient, and probably responsible for a lot of the "sag" that people associate with vintage amps. In all my hundreds of trips to the desert, I have only seen a (very) few snakes. During the day, particularly when it's hot, they tend to hide out in shady areas or underground.....thank heavens :)

[@pauldow1648]

Enjoyed the geological tour and jeep ride as well as the electronics. 😊

[@UncleDoug]

That's good to hear, Paul. Thanks for going along for the ride :)

[@LestonDr]

That explains why my 12 dc output of my portable generator went to 29v when I put a full-wave bridge with a filter cap on the output! I wound up taking the cap out to drop the output back to 12v under load. Thank You

[@UncleDoug]

You're welcome, Leston.

[@coltronex]

That Jeep sounds superb,the terrain reminds me of Saudi Arabia!

[@UncleDoug]

Thanks, Colin. The local military base is used to train for desert warfare......in the Middle East.

[@scottjohnson7774]

thanks you answered my question . I usually don't work on tube equipment but I have acquired a few tuners,amplifiers, and a Gen.rad. audio frequency generator. I usually work on large linear power supply 30 amps and up .just finished recapping a HP 5 volt 300 amp power supply. it's amazing how much technology has changed

[@UncleDoug]

+Bryan Sullivan You're welcome, Bryan. Keep up the good work :)

[@murratosmani6517]

Thanks sharing a view of the area you're living in. Looks beautiful! Of course thanks for the great video at all!

[@UncleDoug]

+Murrat Osmani You're welcome, Murrat. We're glad you enjoyed it :)

[@CIPHER7968]

Another great video Doug. Thanks and greetings from the UK.

[@UncleDoug]

+CIPHER You're welcome, Cipher. It's always good to hear from you :)

[@tonypotter1937]

Great informative video, as usual. The desert tour was a pleasure to watch too. As I live in the UK, I don't get see places like this. Keep um' coming my man..

[@UncleDoug]

+Tony Potter Thanks, Tony.....glad you enjoyed both the technical video and the desert tour. Often, when I was a student, my mind would wander to the "great open spaces", so I guess it makes sense now, after a "lesson", to literally go there :)

[@AdmiralQuality]

So great to have you back, Doug! And drones too! Whoohoo! (I used to fly R/C aircraft when I was a rich teen. Would love to try getting into drones sometime too, but I have a feeling I'd miss actually doing the flying. Instead I'd like to use some of that first person video tech to put my head in the cockpit. Maybe even gimbal the camera according to how I turn my head and wear VR googles to pilot! Someday... but music gear takes the highest priority and I don't have enough of THAT either! ;)

[@UncleDoug]

+Admiral Quality It's great to be back, AQ, and it's good to hear that you share my enthusiasm for RC aircraft :)

[@stevenwilliamdewitt]

great video! I am building my first amp with a full wave bridge rectifier so this series is very timely.

[@UncleDoug]

+Steve Dewitt Thanks, Steve......glad the video is pertinent to your current interest.

[@CraigHollabaugh]

Hey Doug, Thanks for the Jeep tour. I hadn't seen the desert like that since my NMSU days. Craig

[@UncleDoug]

+Craig Hollabaugh You're welcome, Craig, and you're not far off.....I was only about 30 miles south of NMSU :)

[@CraigHollabaugh]

+Uncle Doug I figured as much when you crossed the Rio. If I'm ever back down that way, I'll stop by with some dog treats, cat nip and a beer, you decide who gets what.

[@UncleDoug]

That's the best offer I've had in a long while, Craig. I guess I'll get the dog treats and catnip, since Rusty and Jack usually split a beer :)

[@CraigHollabaugh]

+Uncle Doug Well OK then. I'll get the beer here, www.spotteddogbrewery.com/.

[@UncleDoug]

That sounds great, Craig. I've passed by the place many times on the way to the town square in Mesilla but have not (yet) stopped in to sample their products. That may change, however :)

[@frankymcdonald3081]

The dishwasher, with its already ported construction(bullet holes),along with those Edison bottles resembling a mid evil vacuum tube. has led me to believe a "Mad Max" amp was destroyed in a bring your own couch concert where Aunty Entity performed. Rusty must have bad memories of that day and elected to stay home. I'm in the process of buying a transformer for a Magnavox console stereo. You've saved me. thanks Uncle Doug.

[@UncleDoug]

+franky mcdonald It sounds like you've been partaking of some leafy desert plants of your own, Franky :) :) We're glad the video was helpful. Rusty hates anything that might take him to the vet......so he never rides in the Jeep :)

[@rurlyok]

very informative video uncle doug. and the desert looks amazing! cheers!

[@UncleDoug]

+rurlyok Thanks :) Glad you enjoyed both portions of the video :)

[@Torpengpogi]

hi uncle doug, old video but very helpful and informative, here's my 2-cent, 5Y3 is not inefficient as you have mentioned for the Fender deluxe dc voltage measurements, but actually 5Y3 is a very stable and regulated-like tube rectifier as it can control the peak voltage of an ac ht input, imho.

[@3MonkeysGarage]

it's always that one video you skip that catches you in the behind. Well, education... :) Few more parts and some trouble shooting and I will be back in the saddle. Also, need more videos. I have gone back and watched many of them multiple times, and am about to again. As always, great stuff and thanks

[@UncleDoug]

We're glad you're enjoying our videos, AZ. We'll have a new one posted in the next week or two.

[@3MonkeysGarage]

@@UncleDoug Best news all week, Just finished covering my little cabinet with your guidance. Can't wait to see what you and the whiskers crew have next.

[@Woodys_Hobbies]

Nice view Uncle and a very gorgeous jeep

[@UncleDoug]

Thanks, Woody :)

[@liumander]

Everyday my knowledge is clearer. Thanx

[@UncleDoug]

+Edu "Turupá" Sánchez You're welcome, Edu....that's our goal :)

[@MauroSedrani]

Desert is magic! Thanks for sharing!

[@UncleDoug]

+Mauro Sedrani It is indeed, Mauro. You're welcome :)

[@steelcity321pb6]

Douglas, This video takes me back to over forty years ago when I learned about this subject in college. At the time, I was serving a five year apprenticeship for television and audio (along with some white goods) servicing. Throughout my five years (1971 to 1976 - aged 16 to 21) my employer let me have one whole day (known as 'day-release'), with full pay for an under twenty one year old, to attend college, during term-time only, consisting of three, three hour learning sessions, with breaks in between, in the workshops cum lecture labs, starting at 09:00 through to 21:000. As you may imagine, learning, certainly by seven o;clock in the evening, became tedious - all us lads from the engineering departments thought about at that time in the evening was calling into the pub for a few beers, and meeting girls from the hair dressing, catering, caring, and secretarial, departments at our college LOL. At the end of each academic year (June and July) I sat my exams and was always successful - thankfully there were no early January module resits for me. I remember, though not specifically, answering exam questions on this very subject featured in this video, along with rectification. By the time I was growing up towards my teens (during the second half of the1960s), 'horse power' rating for engines was largely 'old-hat'. My dad owned a Ford Popular 103E (he bought new in 1954) incorporating a 10.70cc side-valve engine which I seem to remember equating to twenty-something kW. All interesting stuff my friend, Phil.

[@UncleDoug]

+SteelCity321PB Thanks so much for sharing your reminiscence with us, Phil. I think a lot of us suffered from distractions during this critical formative period in our education. It's almost a cruel joke that when we should be learning the most, we are also endowed with seriously competing hormones and juvenile interests. Still.....I wouldn't change a thing :)

[@SandersAmps]

Sweet! Essential info for any amp build - Thank you!

[@UncleDoug]

You're welcome, Shaun.

[@jeffm8122]

Excellent series Uncle Doug, as one of your other subscribers noted it "has been a good recap". No pun intended. The chart near the end is a good reminder when building an amp to use filter caps with voltage ratings high enough, especially if you're going to use silicon diodes. Then, if you throw a "Standby" switch into the mix you can really strain the first electrolytic. Personally I don't like "Standby" switches these days, in younger times I did because I thought if Mr Fender used them it must be right. Really like the trip in the desert. There's only one place for a graffiti vandals spray can and the sun don't shine there.

[@UncleDoug]

+Jeff M Thanks, Jeff. You make an excellent point about the voltage rating of the first filter cap.....thus Fender's utilization of a series pair of 70uf @ 350V electrolytics in this position, yielding a net of 35uf @ 700V. I too have no use for Standby switches. Once you learn about amp circuitry, you see how they can cause much more harm than good. We're glad you liked the desert video. So far, it's the final refuge from the depredations of (most) foolish people.

[@mixolydian2010]

Thanks so much Doug you really have got on top of this subject and now i understand RMS. I have always wanted to know where you go when you are not making your great videos. The desert is a beautiful looking place. I live in the UK and deserts are hard to find lol and most of the "nearest" ones are a bit risky at this moment in time. I love climbing mountains and fells and just taking myself off somewhere and have an adventure. I like where you go. Take care and all the best to Jack, Rusty and Mrs Doug.

[@UncleDoug]

+mixolydian2010 You're welcome, Colin. It's great to hear from you. Rusty and I are pleased that our video was helpful. Yes, this is what I am often doing, between videos.....as well as working on the Jeep to improve its ability to take me to these remote areas. As always, the crew at Rusty's Garage wishes you the very best :)

[@cosmicray007]

Wow, what a great video!!! You are such a master teacher!

[@UncleDoug]

Thanks so much, Ray :)

[@bullthrush]

A good follow up explanation to tie in with the practical demonstration with the different load resistors. All good things to consider for my next build. Rusty looked like he was expecting a Pee-mail on the Jeep. :))

[@UncleDoug]

+bullthrush Thanks, Andrew.....glad you enjoyed it. Rusty hates to ride in the Jeep (he figures it's headed to the vet's office) but loves to sniff the tires when I return home. God only knows the scents they pick up. I tried sniffing them once and only ended up with a blackened nose :)

[@utubehound69]

Love that Jeep Uncle Doug Nice! That's Jeep for 4X4'ing not riding around saying look at my 4x4 Jeep that's never been on a dirt road. I just had the convo on RMS Line 6 Amps is selling a 1500 Watt Gtr Amp. I kept telling them that's Peak @ what ever Hz for a slit sec. the True World RMS is what is relevant. I need to share this with that guys & gals gone goo goo over the 1500 Watt rating on the Line 6 amp. Thx Doug

[@UncleDoug]

+Watchman4u You're welcome, W4. I must admit that a claim of 1500W does sound a little fishy.

[@skycarl]

Great info Doug,,,,, the Jeep is sounding real healthy. The desert stuff reminded me of when I lived in Alamogordo NM Carl

[@UncleDoug]

+skycarl Thanks, Carl. The engine is a 350 Chevy with headers and Flowmasters. You're real close......the Jeep video was shot primarily near Santa Teresa, NM, about 100 miles SW from where you lived.

[@tonymanns8249]

Very good presentation and the Jeep sounds great! Beautiful desert, but being an Ohioan I'd miss seeing trees. You got me on "escarpment", I had to look it up. :)

[@UncleDoug]

Thanks, Tony. Glad you enjoyed the tour. I agree with the need for trees.....that's why I live in an area with irrigation and lots of vegetation, but I'm still only 15 minutes away from the desert.

[@tectalabyss]

Thank you Doug ! For the excellent explanation and for taking us along on your Beautiful ride and hike through the Desert. I have always wanted to see it in person but never got the chance and I agree with you about the idiots that spoil the Beauty of such wonderful places. All our best. Bobby & Molly

[@UncleDoug]

+Bobby Tectalabyss You're welcome, Bobby. We're glad you could join us for this trek into the desert and, as always, wish you our best too.

[@tectalabyss]

+Uncle Doug You are very welcome Doug. I love the jeep by the way.The sound reminds me of an older 40's willys my brother owned many years ago. it had been modified to a v8 though I can't remember the size. I hope to see more videos like this in the future. All our best. Bobby & Molly.

[@UncleDoug]

The Jeep has a Chevy 350 with headers and Flowmaster "mufflers", Bobby. I rarely rev it above 1200 RPM, even when climbing hills :)

[@nusior]

This trip was so cool. And beautiful, kinda "westerny" site. And awesome combination! Vintage tube stuff for a dinner and after that...some... desert... Bad pun intended :)

[@UncleDoug]

Thanks, Nusior. Glad you enjoyed the ride :)

[@davidchatterton5664]

Lovely place you live in Doug thanks for that vid it's almost as if it was ment for me as I had that exact problem when I built my amp ( it works lovely now by the way)

[@UncleDoug]

+David Chatterton You're welcome, David, and thanks for the nice comments. I think it's an issue that lots of people discover "the hard way", and a source of puzzlement to many others.

[@eatingplaydoh]

Beautiful scenery minus the human trash element. Nice CJ as well. Thanks for all you do Doug.

[@UncleDoug]

Thanks.....and thanks for watching, EPD.

[@fullwaverecked]

I have the same issue with my Cool Whip... Great video!

[@UncleDoug]

The nectar of the gods, FW :) Thanks !!!

[@4hammonds672]

hello uncle Doug thanks for sharing those nice images in the dessert. it looks to me like somewhere in west texas kind like where the bigining of lone wolf Mcquade film was filmed. i wish i live there...very nice indeed

[@UncleDoug]

You're welcome, 4H, and you're right about the location.....just a little west of west Texas.

[@PoJoWo]

What a fantastic burble that Jeep has. In the UK the closest we get is the odd ex military Land-rover fitted with the rover 3.5l v8. There is no substitute for cubic capacity as they say. The scenes with you near the railway line brought to mind the old Duel film, and another one with Kris Kristofferson as a desert cop but the name escapes me. As a kid in the eighties I was obsessed with that landscape and the US vehicles. We had a local American car specialist and he used to let me go and hang out and start up the Trans Ams. Maybe I'll make it across the pond one day. Sorry to waffle. What is your opinion of the trick of putting a Zener in the centre tap to lower the B+? I have a lovely early seventies vox ac30, but it's one of the rare silicon rectified ones and it has a rather arduous 440v on the el84s and it's hard to find ones that do not live on the edge at that voltage. Thankyou for such a informative, and inspiring video.

[@UncleDoug]

+PoJoWo You're welcome, PJ. When rumbling through the desert, I sometimes get a "Mad Max" vibe. I guess if Rusty were beside me with a neck scarf, it would be even better....however, he has no love for the Jeep or any other vehicle, primarily due to the fact that they occasionally transport him to the (despised) veterinarian's office. Yes, Zener diodes can be used to shave off B+ voltage, but, due to their heat-producing nature, they generally should be mounted on a finned (if possible) aluminum heat sink.

[@utubehound69]

+Uncle Doug Hahaha Mad Max vibe, yer killing me . My Rusty would jump in anyones vehicle for a ride, sadly he was kidnapped. Rusty was a mini Dachshund.

[@UncleDoug]

Glad you liked it, W4. We're really sad to hear about your mini-Rusty. People who steal dogs are an even lower life-form than those who deface the desert.

[@utubehound69]

Uncle Doug That broke my heart. They become like family.

[@UncleDoug]

I completely understand and sympathize :(

[@MrMac5150]

Looking forward to our next lesson.

[@UncleDoug]

+MrMac5150 It's in the works, Mr. M, so stay tuned :)

[@MrMac5150]

Uncle Doug Will do.

[@bertuspa3grn]

Hallo Great video again Nice view from the country in Texas you can use that beautiful jeep I think the wether is often good for a ride In Holland we need a roof on that type of cars Thanks Bertus

[@UncleDoug]

+Bertus pa3grn You're welcome, Bertus.....glad you liked the video and the Jeep tour :)

[@ShrimpsTonic]

Love the desert shots!

[@UncleDoug]

We're glad, ST. Rusty and I really love it too. It rejuvenates our tired old batteries :)

[@AndyWragg]

Great video. Seen the effects myself with the JTM 45 build during the testing stages. Like the desert tour there, Shame the shooters don't collect up their brass/empty shells. Very disrespectful of nature. Where is it you live? I'm guessing New Mexico with all the desert and the Rio Grande.

[@UncleDoug]

+Andy Wragg Thanks, Andy. Yes, if people enjoy an area, the least they could do is to keep it clean. Even if my wife didn't constantly hound me, I wouldn't throw all my trash on the living room floor. You're right about the location.

[@utubehound69]

+Uncle Doug That really make me mad to see ppl throwing trash in nature like that so sad. Oh & the Chemtrails being sprayed over the world. You can see them when you are looking @ that Ridge w/the RR trx running by it.

[@allaird1]

Great video Doug. I know what u mean about the garbage left by others. I usually do a bit of clean up to try to help. I do like comming up on cool historic items as well. Mabey if the junk is there long enough it will be "historic".lol. I love the desert as well.

[@UncleDoug]

+allaird1 Thanks, A1. It's a beautiful and rather vulnerable place. I've been picking up junk whenever possible and trying to do a little in return for the joy the desert has provided to me.

[@robzecc]

Thank you for the desert trip

[@UncleDoug]

Thanks for joining me :)

[@cmguitar50]

Doug Great video (as usual),,As far as the 5Y3 power supplies..- what makes the B+ of the Supro higher than the Deluxe , even though it's RMS VAC is lower?

[@UncleDoug]

Thanks, CMG. The Supro is single-ended, while the Deluxe is double-ended. Two output tubes flow more current than one, resulting in lower voltage levels.

[@georgekrabs6948]

Wonderful ending, really enjoyed your Jeeping, hope you were watching the road straight ahead when you were driving or was that aunty filming, cos I know Rusty was home.

[@UncleDoug]

Thanks, George. Actually, I was holding the camera in one hand and the steering wheel in the other. Fortunately, the Jeep has power steering, so this is a little scary but not physically difficult to do.

[@SuperCarver2011]

Nice set of pearly whites you show there in yiour diagram, Uncle Doug. Recollecting my AC theory, Peak, peak to peak and Root Mean Squared (RMS) I always understood as its part of the Sine Wave math. RMS can be considered the "heating effect or effective value' of current and voltage for a given voltage in a resistive load. For a cyclically alternating electric current, RMS is equal to the value of the direct current that would produce the same power dissipation in a resistive load At the peak of the 60hZ sinewave voltage, there isn't a lot of energy in the transition between the positive slope cycle sine wave hitting it's peak, then transitioning down in its negative slope cycle. All together when you analyze the AC sine wave there are 4 quadrants ( 2 positive going and 2 negative going . peaK IS 1.41, (RMS x 1.414) IE: 240 volts x 1.414 = 339 volts.

[@UncleDoug]

+SuperCarver2011 Excellent analysis, SC. Hopefully, I was able to convey most of this in the video.....particularly the equivalence of power dissipation between RMS and peak AC. Thanks for your knowledgeable input.

[@rheidtech]

hey rusty!. great vid ud. thx for the ride.

[@UncleDoug]

+R HEIDEMAN You're welcome, RH. Thanks for going along with us :)

[@chennemeyer]

What a great video, and good guy thank you for the upload and time

[@UncleDoug]

You're welcome, Chuck. Thanks !!!

[@spacegoat77]

Love your videos. Man are they informative. Off topic though. What years your Cj5. I’m driving a 76 I rebuilt a few years back. Sounds like a larger engine you’ve put in it. Very envious of your desert play ground.

[@UncleDoug]

Thanks. As I recall it was a '72, with a Chevy 350 engine with TH350 auto transmission.

[@MegaTubescreamer]

great to see the typical habitat of the greater uncle doug species, like many similar uninhabited places, there are usually signs of transient disrespect and the odd not so sweet suite fly tipping, most enjoyable tho ,thanks uncle doug,

[@UncleDoug]

Thanks for joining us, William. Your assessment seems quite accurate :)

[@jenniferjohnson708]

Great video. Loved the explanations. It really helped to clear up transformer selection for me. By the way what kind of grounding scheme do you use in your amps?

[@UncleDoug]

+Jennifer Johnson Thanks, JJ.....glad you enjoyed it. This subject is covered in my Supro Tremo-Verb series. Check out the part that relates to the circuitry.

[@BMRStudio]

:)))) Just pleasure to watch. Rusty is not in the desert with You?

[@UncleDoug]

+BMR Studio Thanks, BMR. No, Rusty views all methods of transportation with equal suspicion, especially after being taken to the vet a few times in various vehicles. I should have started him riding around when he was a puppy, but sadly did not.

[@BMRStudio]

So he is a bio dogy :) He dont like transportation. He prefer run and walk :) I like Rusty and the cat :)

[@UncleDoug]

Actually, he prefers eating and sleeping.....but as I get older, so do I :)

[@valakatz3967]

Thank you for sharing beautiful video.

[@UncleDoug]

You're welcome, VK.

[@emergencynurse02]

You just answered a question I had a build I did for someone!! thanx for the video's ! I watch all of them....Cool desert tour too....The Astronomy must be incredible in those skies....I try to do "Serious" imaging here in Michigan ....but ....light pollution and clouds make it difficult.

[@UncleDoug]

+GuitarHack123 You're welcome, GH. We're glad the video was helpful and pertinent to your interest. Also, glad you enjoyed the desert tour.....the sky is pretty spectacular at night :)

[@farmerwayne1404]

Beautiful desert !

[@UncleDoug]

It really is, Wayne. I love it :)

[@marklange8894]

Then end of that video was just plain cruelty. I grew up in the Sonoran Desert (Van Horn) you sure know how to make a guy homesick. Really beautiful video of the desert. I really miss the mountains and the stars. There basically are no stars in North Texas, too much humidity and light pollution.

[@AdmiralQuality]

+Mark Lange Like the song goes, the big, bright stars are only found deep in the heart of Texas. (Gotta love a state song that discriminates against the fringes! ;) )

[@UncleDoug]

+Mark Lange Thanks, Mark. I understand your feelings about the desert. It's a big reason why I have stayed in this area all my life :)

[@TechTins_Projects]

The road trip was a nice surprise. I am building a PSU and yep I made the same mistake 240 to 12 0 12 and was expecting 12v out and got 18v out. That was then regulated down to 9v but when attached any load that dropped then to 8v. Used adjust resistor to finally get it to steady 9v but was all very confusing. Pity I did not see this video first!

[@UncleDoug]

+Tech Tins Yes, indeed, TT, this unexpected phenomenon has caused grief to a lot of techs and circuit builders. It seems counter-intuitive that you can get so darned much filtered DC voltage out of a lower-rated PT.....but, as we both found out, you can :)

[@jameshyatt9529]

Hello Doug. I doubt you'll see this but I had to subscribe. You had me at Fender Amps, then your sweet jeep. Then i see your a desert rat as well. I had a place in the high desert of the Mojave in Cali for many, many years. Now I live in the land of ice and snow in NW Montana. I miss the desert terribly. Where are YOU??? Thanks big time. Love to Rusty and Jack.

[@UncleDoug]

You're welcome, James. Welcome aboard.....thanks for subscribing. We live in the West Texas/Southern NM area.

[@rádiosantigos1958]

Good explanation again. Thanks.

[@UncleDoug]

Glad you enjoyed it, RA.

[@OldIronShops]

was thinking you said you had a video related to you transformer series that was you building a tremo standalone unit having trouble finding it

[@UncleDoug]

Perhaps it was in the Supro Tremo-Verb series, OIS.

[@OldIronShops]

@@UncleDoug ahh i think i found it . perhaps it was the 6G15 series buy on second thought i do think i that might be it oh well back to the archives.

[@td7456]

Great info, loved the desert tour too. Not a whole lot of that desert stuff in Ohio.....LOL! I've heard of some pretty big diamond back rattlesnakes out there, ever see any, they (and any other snake) scare the heck outta me..

[@UncleDoug]

+Tim Dockery Thanks, Tim. Yes, I have run across a few large rattlesnakes, but they are not particularly aggressive. It does tend to scare the heck out of you, however, and I quickly retreat to a safe distance. They tend to coil up and warn/threaten you.....which I take quite seriously :)

[@MrTrip49]

First I would like to thank you for posting these videos. I've watched all of them and have learned a lot, and I look forward to more videos. My question is this, I have a leslie 147amp and the power supply is a full wave bridge rectifier. According to this video you say that the B+ voltage is on the plates. I always thought and correct me if I'm wrong that the B+ voltage is the highest voltage coming off the rectifier. Like on my leslie 147amp has 430 VDC coming right off the rectifier than goes through the choke and than the filter caps and so on. And of course has voltage drops. So when I measure voltage on the plates I have 415 VDC. As per the schematic. So is the B+ voltage on my amp 430 VDC Or 415 VDC? Again I enjoy your videos and look forward to more of them.

[@UncleDoug]

+MrTrip49 You're welcome, Mr. T. The term B+ refers to the fully rectified and filtered, smooth "battery-like" +DC being applied to the amp circuit, so it's generally measured at the center-tap of the output transformer (DE amp) or input to the OT (SE amp), just prior to distribution to the output tube plate(s). Most people consider the OPT as the "beginning" of the amp circuit. I would say your B+ is +415VDC.

[@MrTrip49]

Thank you for responding. I understand now. Look forward to your next video.

[@UncleDoug]

You're welcome, Mr. T :)

[@donaldfilbert4832]

Uncle Doug. That chart you introduce at 7:02 is fantastic !! Is that your own compilation from your historic experimentation ? Or did you source it somewhere? If so - I'd love to know the source - for possible additional information. However - so far I have not found any Internet site that comes near to providing the kind of pertinent detail you provide !! Thanks !!!

[@UncleDoug]

+Donald Filbert You're welcome, Donald. Some of the data on the "Real World B+" chart was from personal experience and some was taken from schematics. The pattern throughout, however, is very clear when it comes to the effect of filter caps, type of rectifier tube, and the vastly superior efficiency of diode rectification.

[@donaldfilbert4832]

+Uncle Doug Thanks for your response !! As to the the validity of the data in the chart - I have no doubt !! I have seen lots of "Engineering" types of charts re" tube circuit" that were overly complicated and worthless in real application; and was delighted to see your succinct and completely relevant chart. And was just curious if you had a secret site where there might be more treasures .... LOL !!!

[@UncleDoug]

I tend to prepare charts and diagrams like this for my videos, Donald, and then post them.....so they're all currently on YT and available for scrutiny. I may hoard vacuum tubes and old amps.....but I don't have any secret caches of data :)

[@elluisito000]

that NM desert reminds me a certain Mr White, also known as Heisenberg :D BTW did Rusty go with you?

[@UncleDoug]

+luis colmenares Rusty considers all means of transportation as being sent by the devil to take him to the vet. He won't get near the Jeep unless the engine isn't running :) Yes, it does look like the Albuquerque desert......especially with all the parked RV's and guys running around in their underwear :)

[@chakathewolf]

It can go higher than that. The "Champ" power transformer that Triode sells is spec'ed at 650 Volt center-tapped. (325-0-325) With a 5Y3 it produces around 490Vdc before the other tubes heat up. I used two 47 microfarad 450 volt caps in series for the first filter stage. After warm-up it still cranks out 400 volts or so. (I don't remember offhand what the measured no-load AC voltage is.)

[@UncleDoug]

+Chaka Wolf Yes, indeed, CW. During the initial AC input surge, which can be monitored with a voltmeter, the voltage can quickly (and briefly) reach scary levels.....thus Fender's use of two 70uf @ 350V electrolytics in series (just as you did) in the first cap position of the Bassman circuit.

[@bradrebar101]

Uncle Doug is there formula that is used to determine B+. I'm using tubes different than the usual ones listed here, for low watt amps, i.e 6aq5. I know this is a 5+ year old vid but I just had to ask.

[@UncleDoug]

Not a formula, but a book.....a GE, RCA, or Sylvania tube handbook.....and the manufacturer's specs for transformers. Also, some personal experimentation never hurts.

[@ImTheReal]

Sharing! o.O' Pretty crazy film until drive the Jeep (good motor sound). That place is a treasure :) How about the energy consumption over the different rectifier?

[@UncleDoug]

+Humberto Martins Ferreira Junior Thanks, Humberto. As you can see from the chart, diodes are far more efficient than any tube.....even the mighty GZ34.

[@ImTheReal]

+Uncle Doug I'm feeling a little short circuit on my brain... well, could be a loosing screw. Understood Master. Making sense now. :)

[@PatrickInCayman]

Thanks for the video Uncle Doug, it certainly rectified some of my misconceptions

[@UncleDoug]

Glad to help, Pappa :)

[@SuperCarver2011]

Thank you for your video scenic vistas of the Sonara desert? it is sad to see the effects of man on the desert that was pristine at one time. Sad to see the effects of those ignorant and uncaring that turn it into a dumping ground.

[@UncleDoug]

+SuperCarver2011 You're welcome, SC. Fortunately, the negative effects of vandals is generally limited to the area near paved roads, since these fools are too lazy to drive very far to dump their refuse. Once you get a couple hundred yards from "civilization", most of the damage subsides.

[@SuperCarver2011]

+Uncle Doug My daughter lives in Phoenix and she loves it there. I have visited on occasion and enjoy the scenic Vistias, especially in the Sedona area.Been there a couple times. Back in'95, when I was a lot younger, I rented a Harley and was going to explore a lot more,but this was in march and the weather wasn't particular suitable for long distance motorcycling, so I didn't see those famous "wild west" places such as Tombstone and ShowLow. Missed that opportunity and due to my current health as well as age, it won't happen again.

[@UncleDoug]

What a shame, SC, it would have been a great adventure. I had to give up vintage motorcycles when my knees started acting up.....I could no longer kick-start them. I miss them, but found new, replacement hobbies. Hopefully, you have done the same.

[@SuperCarver2011]

+Uncle Doug I have carving and play my guitar. I contracted myositis in my legs in 2001 after chemo. I was still riding a Vtwin then, but the knee muscles got weaker and weaker so I had to give up the big bike in 2004. I still had a japanese 650cc (similar to the old Triumph 650) that I sparingly rode until 2006. Had to give that up too. Gave up driving in 2012..couldn't lift my foot from the gas to the brake and I was an accident waiting to happen. Now I'm driving a power wheel chair in my house and a scooter outside. Not lloking forward to the next 10 years though as I get weaker. over all..in my 70s now. Now I',m playing "Yesterday...when I was young," by Roy Clark. "Yesterday the moon was blue And every crazy day brought something new to do. I used my magic age as if it were a wand And never saw the waste and emptiness beyond. The game of love I played with arrogance and pride And every flame I lit too quickly, quickly died. The friends I made all seemed somehow to drift away And only I am left on stage to end the play."

[@UncleDoug]

A beautiful song, SC. The lyrics mean a lot to all of us old timers looking back on our generally under-appreciated youth.

[@audiotechlabs4650]

1 more situation avoided by an excellent explanation! It goes to show you must measure all voltages from the power supply before installing the tubes. Great! Thank you for sharing and you National Geographic tour of your beautiful state(except for the damage otherwise uncaring individuals have made) was a hugh (supposed to sound like D. Trump) bonus! Thankz

[@UncleDoug]

+Audio Tech Labs You're welcome, ATL....glad you enjoyed both the tech video and the Jeep tour. Thanks for going along for the ride :)

[@douglasRbrown]

great video, whats in the Jeep? SB350-TH400? maybe stall converter?

[@UncleDoug]

It's a Chevrolet 350 with a TH350 transmission, Doug. I believe the torque converter has a normal 1500 to 2000 RPM stall speed.

[@dhpbear2]

Ooh! Speaker stands! (10:31)

[@UncleDoug]

They wouldn't vibrate much :)

[@dantihon3997]

Brilliant !

[@UncleDoug]

Thanks, Dan.

[@diabolicalartificer]

Thanks again, knew most of what you covered in this series of video's, but as always, I learnt something new. Some folk have no respect for the planet, we get em here in the UK too. Every walk, I come back with bags of rubbish thrown down by %&^£$'. Not a fan of gas guzzlers, but your jeep sounds sweet. : ) Keep em coming. Best regards.......A.

[@UncleDoug]

+Dr Wobble You're welcome, Dr. W. If we filled in even a tiny gap of knowledge, then the video was a success. Amen as to the carelessness of &$@%*?$ who shower our planet with trash. May they all go to a special form of hell in which they roam a reeking dump.....forever :)

[@silasfatchett7380]

@@UncleDoug Amen to that!

[@FishloreJimson]

If I have 550V (no output tubes drawing current) coming out of a bridge rectifier, is there anything I can do to take the edge off before it hits the four 6L6s? I have the basic reservoir of 50/350 uf in series with 220K resistors parallel to them before going to the CT of the OT. I was trying a point to point project with a pair of transformers taken from a PCB amp but I'm not sure if I can deal with that voltage coming out. Thanks.

[@UncleDoug]

The only accurate voltage measurement is made while the amp is complete and functioning. Without any load (i.e. output tubes), the voltage will be abnormally high. Try it and see.

[@FishloreJimson]

@@UncleDoug Thank you. My current limiter is running away after the output tubes start drawing current. I can't take any usable readings yet. I wasn't sure if this was the cause. I'll go through the circuit again. Thanks again.

[@jensastrup1940]

I'm sorry but this is one of the few cases where I don't understand your otherwise impressively clear explanations, Doug. More specifically, I don't understand (at 4:00-4.15) where the capacitor gets the energy to fill up to the peak level. It seems that you get something (the difference between the RMS level and the peak level) for free?

[@UncleDoug]

As the signal wave is rising (gaining in voltage) it charges the capacitors, and when it falls, the charged capacitors discharge to fill in the ripple troughs, Jens. You can think of it as a battery. When the voltage in the signal is rising, it charges the battery, and when it is falling, the capacitor "battery" discharges to fill in the trough. I hope this clarifies the subject.

[@jensastrup1940]

Thanks Doug. I get the principle (I think) but I'm puzzled that the capacitor has enough stored charge to fill the ripple troughs completely. In the beginning of the video, you show how the part of the PP signal that is above the RMS value corresponds to the part of the trough that is below the RMS level. Then from 4:00 in the video, it seems to me you are converting the peak-to-peak signal to an RMS signal of equal value without the "penalty" in level.

[@UncleDoug]

The capacitors actually contain far more voltage than necessary to fill the voids, Jens. Like a 12V battery that only releases and accepts 250mV. On initial start-up they fully charge and then only charge and discharge a small amount when filling in the ripple. The peak voltage is 1.414 times the RMS, so when the output is charged up to peak voltage, it is much higher than the RMS output of the transformer......which surprises many people. For instance, a 350-0-350VAC transformer will produce an output of 495VDC (it's actually less due to inefficiencies in the transformer and rectification......more like 435VDC).

[@jensastrup1940]

Aahh, I see. Thank you again.

[@irusman62]

where does the B+ get its name from? are there A+ and or C+? are the secondary windings labeled A, B, and C?

[@UncleDoug]

In the old days when radios were powered by batteries, the battery that provided the positive high voltage was called the "B battery".

[@irusman62]

@@UncleDoug ohhhh k that’s why, thank you

[@PanzarMetal]

Transformer rating 350-0-350, meaning it gives out 2x350V line to 0 or its can produce 700 volts peak to peak. Multiply 700*0.707 and we produce 494.9Vrms, in other words this should be the rectified out put voltage. Just remember Voltage depends on the point of reference!

[@kardRatzinger]

+PanzarMetal not at all. Transformer rating 350-0-350, meaning it gives out 2x350V line to 0 or its can produce 700 volts RMS, not ptp.

[@UncleDoug]

+PanzarMetal Since center-tapped (350-0-350 VAC RMS) power transformers are intended for Full Wave rectification, the AC output would be equal to either of the two secondary half-windings or one-half of the full secondary winding, i.e. 350VAC RMS. After smoothing by the filter caps, which will charge the ripple up to peak value (not RMS), the smoothed DC output will be about 460VDC. If the full secondary winding (700VAC RMS) was subjected to Bridge rectification, the smoothed output would be in the neighborhood of 990VDC.

[@eddgong]

Hey Uncle Doug , your desert is a lot prettier than my desert , your jeep is prettier too lol , i had a 76 cj5 with a 308 I think maybe 304. nothin fancy but enjoyed it , my 95 Cherokee sits in the That is one clean ride , dig the bead lockers and skins . looks like it will get you in and outta there and still have a decent hi-way ride .......as far as jeeps go any way.. My Cherokee just sits in the driveway ,cant afford the insur. and registration , hell I dont have a drivers license either but it is RED grin just sayin hi

[@eddgong]

Now I have Marty Robbins running thru my head .........probably be humming El Paso for the next 2 days ......

[@UncleDoug]

Greetings, EJ. It's always good to hear from you. I hope all is going well :)

[@eddgong]

All is what it is what it is and what it is is hot out here hay wearing a fur coat .....My front porch thermometer was 124 yesterday how about you in your your neck of the desert . 124 is still better than a hay field in Louisiana

[@UncleDoug]

My thermometer is in the shade on my back porch and it's been registering up to 108 over the past week or two. The bad part is that it stays hot at night.....around 90 degrees......so each day already has a head start on being awful.

[@geraldhinson]

I'm a bit confused by the numbers. Why does the 5Y3 convert 325 to 360 on the bottom line, but convert the 330 to only 336 on line 3? Feed it less and it gives you more???

[@UncleDoug]

+Gerald Hinson The Deluxe amp has 2 output tubes so the circuit flows more current, making the voltage lower than the Supro amp, which has only one output tube (and thus flows less current so the voltage is higher).

[@geraldhinson]

+Uncle Doug Ah, got it. Thanks for the clarification. I missed that if you said it in the video.

[@UncleDoug]

You're welcome.

[@mikeelmore6040]

Great video very informative as always. Sorry to see your views and recreation spoiled by selfish and inconsiderate people. I can't stand that we have become such uncaring people!

[@UncleDoug]

+Mike Elmore Thanks, Mike. I would like to think that the graffiti and dumping are done by a tiny minority of the local population. Far more people are considerate and conscientious about the cleanliness of the environment.....I hope :)

[@bevo65]

Love me some El Paso del Norte! Hook 'em.

[@UncleDoug]

Likewise, Bevo, but I miss being able to go to Austin Vintage Guitars :)

[@Alpha1545]

Could you be a rail-fan. What a great spot to do it. Now about the 60's underrated hp specs. That jeep's motor does not sound anemic to me. Now I know that mill came from a 60's design can I get a oh-yea !!!

[@UncleDoug]

+J&B Fix it shop You're right, J&B....it's a 350 Chevy with headers and Flowmasters, and the serious cam lope adds to the fun :) Yes, I love to explore around old railways and collect RR memorabilia.

[@Alpha1545]

Yea rail fan is fun no doubt. Now I will say, that sure is a lot of motor for that jeep. be careful we need more schooling and don't want teacher crashin out!

[@UncleDoug]

The power combined with the high center of gravity make for a scary ride sometimes.....but I'm securely harnessed in, so all that's at risk is my pride :)

[@Alpha1545]

Ok just saying.

[@UncleDoug]

Thanks for your concern. I'm very careful.

[@harbselectronicslab3551]

Nice Video, and Nice Jeep.......you really have to love open top Jeeps and the like........its a bit like owning a motor bike for us old farts without the pain of falling off...... lol

[@UncleDoug]

Thanks, HE. Yes, the sensations of wind exposure and "freedom" are quite similar.

[@thermionic1234567]

Any interesting minerals/fossils out there?

[@UncleDoug]

Not so much in the desert, Jeffrey, but there is another (mountainous) site nearby where almost every rock you pick up has fossils within it. I haven't made a video of that spot.....yet.

[@blueties1]

As you state, if you increase the B+ load, more current flows and the B+ voltage will decrease (in an unregulated power supply). The B+ voltage decreases due to the increased voltage drop across the internal impedance of the power supply. At 6:15 you state that "(Current and Voltage are Inversely Related)". That is completely misleading. As I'm sure you know, e = iR (E =IR, v = iR, V = IR etc.). This is a linear proportional relationship, not an inverse relationship. At 6:38 you state that " ... as the voltage goes up the current goes down". By that I assume you mean that as the load current decreases, the B+ voltage increases. But the way you state it makes it sound like increasing the voltage will decrease the current, and we know that to be the inverse of what happens.

[@UncleDoug]

People who work on amplifiers understand exactly what I am saying, B1, particularly when biasing output tubes. Increase of the plate current will result in a decrease in plate voltage, and vice versa. I realize there are more elaborate ways to express this relationship, but the fact that I don't resort to elaboration is exactly why so many viewers enjoy my videos. Thanks for your helpful input.

[@MrMac5150]

Maybe we should try Rust out, on some Slim-Fast.

[@UncleDoug]

+MrMac5150 Just like his old "Uncle", it's all muscle, Mr. M......I swear :) :)

[@MrMac5150]

Uncle Doug Sorry I was not wearing my glasses, I should have noticed that, just from his stance.

[@UncleDoug]

Lots of people seem to make that mistake, Mr. M, but when they see him "in action".....i.e. eating and sleeping.....they realize the truth :)

[@MrMac5150]

Uncle Doug How wrong can I be, please accept my apology, for such a incorrect assumption.

[@AROSFC]

Tks for the lovely views of the desert. Unfortunately the human species keeps trashing everything....on this side of the atlantic is the same thing, unfortunately.

[@michaeld8975]

You best be careful showcasing that desert. Next thing you know most of LA's homeless and crack heads will be flocking to the area. What with all that warm weather, Picasso artwork, stylish home furnishings and rubbish to rummage through. It's sure to be a shopping cart pushers haven. And who you got to blame when you come across a Graig's listing for a red jeep no tittle to accompany it. It'll be like the Gold Rush of 1849 sans sifting pans.

[@UncleDoug]

+Mooky Mann I never thought of that, MM.....a scary concept indeed. I guess the one redeeming feature is that, hopefully, these weasels don't spend much time watching YT videos on amp circuitry. Just the same, I'll have to be more careful in the future and make it appear that there are lots of cops, truant and probation officers, child support monitors, and employment offices out there in the desert :) :)

[@thesillyhatday]

Even though I am familiar with the subject, this video series has been a good recap. Plus it's still satisfying to hear others share knowledge. With a great ending. I've been waiting to hear the jeep in action. Please keep making videos, this has become one of my favorite channels. Dan

[@UncleDoug]

+ubanoob Thanks, Dan.....glad you enjoyed the video and the tour :)