Tube Power Shock!

Light-em up! Here is a Tube Power primer that covers the basic voltages and current requirements for the Filament, Bias Supply and The B+ for Common Radio and Audio Amplifier Projects. Lets tame those switchers for valve supply use.

[@db3501]

Running the plates off a low-voltage supply... I like that idea.

[@OpossumPiper]

Great solution to reuse some salvaged parts! Thanks for this video

[@Swamp-Fox]

Now I have to go dig out my box of wall warts and see what I can find!

[@acestudioscouk-Ace-G0ACE]

I'm glad to see that I'm not the only one running scared of using valves! Thanks for this video, it's beginning to give me the push to try and the switcher filtering will be useful in a lot of projects. 🙂👍

[@MIKROWAVE1]

This is simply shocking!

[@acestudioscouk-Ace-G0ACE]

@@MIKROWAVE1 LOL 🤣

[@Homer19521]

Classic Mikrowave. 👍

[@roccogarzione8410]

Thanks for these Mike. You've been my mentor into the world of low voltage tubes. When I studied engineering emphasis was totally digital with a little analog thrown in for completeness. One thing I'm having success with is looking for the AC wallwarts and simple voltage doublers and triplers circuits with rectifier diodes and electrolytic caps. Using the 12 and 24VAC bricks are working great like your cleaned up switching supplies.

[@davidportch8837]

love this Mike... many thanks

[@Guieno]

Hi Michael! I love every video of you. Even in my early youth, i made himself pirate tube transmitters. And already in adulthood, a tube sound amplifier, because then it was fashionable. My regards. Geno UR3QX (Now from LZ) 73!

[@MIKROWAVE1]

Harr! A little Pirate were ye.

[@blacksmock445]

Another use for wall-warts, as mentioned by @roccogarzione8410, would be to use 12 or 24 volt ac units, often used for Christmas tree lights and similar uses. These could supply a B-battery (HT) voltage of between 30 and 70-volts at, say 50mA, if used with a voltage-doubler rectifier circuit. Even a 12-volt unit often produces 15-volts off-load, that is 21 volts peak, giving around 40-volts dc after rectifying with a voltage-doubler. The wall-wart keeps the mains voltages safely enclosed in a sealed plastic case. Valves (tubes) with ac heaters could be connected in series across the low-voltage ac output, provided that they all drew the same current, perhaps 300mA in many cases.The voltage-doubler is also useful for deriving + and - supplies for op-amp power supplies, without using a centre-tapped transformer.

[@MIKROWAVE1]

Yes and voltage multipliers are completely practical and less noise than switchers.

[@FarleyHillBilly]

ECH83 and EBF83 were used in hybrid car radios and run with 12 volts on the anode.

[@db3501]

EF95 pentode also

[@robertmeyer4744]

that nice video. been playing with tubes many years. many battery tubes out their . have some 2V directly heated type. some old battery sets used them . 2V A battery was lead acid and you take it to a place to recharge. today this is easy. 2V AGM cells easy to find. with the 1.4V tubes I found a NiCd cell works fine. I even have a small flooded type. 6V tubes is easy. 6V lantern battery spring top. walmart has rechargeable AGM type in the store. and a great find is old 12V car radio tubes. tubes made to run 12V on the plate. got a couple of out car radios that use them. the audio was a germanium transistor. I have a bunch of small 12V AGM battery's 4Ah to 10 Ah. easy to get 32V/48V. what I have done for making a A,B supply for old tube sets is went analog reg with HV transistor and Zener diode. 7806 reg ic good for a amp also works for filament. I went with LM 317K ADJ so I can set 1.2V to 6V . made on a piece of wood. worked many years and still does. at a hamfest some years back ,I brought old battery tube set. it had 45V B battery. I had the A in NiCd in radio. I ran on 48V EzGo golfcart with a 3V zener to make appx 45V . was a big hit. driving around listing to AM/SW tube set. love the low voltage tubes . hardly a shock at 48V . lots of fun. 73's

[@MIKROWAVE1]

All good stuff Robert!

[@JCWise-sf9ww]

Mike are you forgetting that car hybrid AM radios made in the late 1950 through the early 1960, used tubes specifically designed to work off of 12.6 vdc for the plate circuits! ... Good primer course on making switching PS 's quieter. You were rather bref on filtering the AC line side and putting the works inside a metal box which is an excellent idea! I have experienced a switcher PS that interfered with AM radio anywhere in the house, I had to replaced it with one that did not. Sw'er RFI is a real issue.

[@MIKROWAVE1]

Oh I have them, but the Space Charge tubes are a bit special for most folks who want to get started with tubes.

[@JCWise-sf9ww]

@@MIKROWAVE1 Yes, Space charge tubes like 12J8, 12K5, 12DL8, 12DS7, etc., were meant for driving a germanium power transistor, but tubes like the triodes 12AE6, 12FK6 and pentodes 12CX6, 12EK6, 12F8 and many others are not space charge tubes they are connected just like the higher voltage cousins, but optimized for 12.6 vdc operation, some are rated as high as 30vdc.

[@scharkalvin]

Many pentodes can be run off of 9 volts in space charge mode. You apply B+ to the first grid, and use G2 as the signal grid. G3 is either connected to the cathode or the plate.

[@db3501]

B+ on the G1? Are you sure?

[@scharkalvin]

@@db3501 YES. Mind you we are talking less than 12v here in space charge mode. This was very common in tube car radios of the late 50's to early 60's.

[@db3501]

Ok good, nice to know. But it's only the RF frontend. Probably no way we could build a complete set around a 12V supply.

[@scharkalvin]

@@db3501 Car radios in the late late 50's and early 60's used a special set of vacuum tubes designed for space charge operation. These included an RF amplifier, Converter, IF amplifier, detector and first audio stage. The speaker was driven by a Germanium power transistor and a special tetrode space charge tube provided enough drive for the power transistor, which was operated in class A2.

[@db3501]

@@scharkalvin Good stuff really, I didn't know that :-D On the contrary... your AM stations were much stronger back then. You now have environmental-friendly 5kW or so. Not much fun to operate an imperfect radio under these conditions, sadly.

[@Broken_Yugo]

Shop around for cheap 9 volts, the demand is low so the pricing is pretty arbitrary, shoot for under $1 each, maybe $1.50 for alkaline. Best deal on carbon 9 volts I've found is at Big Lots, currently 2.89 for 4. I prefer them over alkaline for most 9V stuff as they don't tend to be as destructive if you forget about one left in some piece of test equipment. Amazon is usually best for cheap Alkaline, I've had good luck with the Delco brand.

[@MIKROWAVE1]

True but I have been burned by shoddy construction and dead cells with the cheap ones.

[@FarleyHillBilly]

Electrolytic caps are wound foil construction, which makes them inductive at switcher frequncies. Better to use tantalum SMD 10uF and some ceramic 100n caps

[@MIKROWAVE1]

Wow a real engineering approach! Yes gaining that last 3% of efficiency or 10 dB of rejection in switchers is what the 90's were all about, as switchers and controller ICs really became mainstream.

[@FarleyHillBilly]

@@MIKROWAVE1 ESR of the res cap is the main problem, my 5v 1a psu had 2v of noise on it Expensive low ESR tants fixed it.

[@XPFTP]

why cant you put 2 in series. ??? ive done that with 2 18v printer supplys seem to work fine. no noise. just asking

[@MIKROWAVE1]

Theoretically they are isolated from the line. So it should work. Be careful with line voltage.

[@Steve-GM0HUU]

👍Thanks for video Mike. In terms of repurposing wall-warts for HT supplies, one thing I have wondered about but never tried for this type of application is connecting a few SMPSUs outputs in series. There shall be some precautions associated with try this - DO NOT TRY THIS UNLESS YOU UNDERSTAND THE RISKS. However, if you had, say, x4 24V dc wall-warts of appropriate design, in series you would get around 100V dc. Could be a cheap and cheerful way to make an HT supply with surplus mains adapters for laptops, printers, etc? I am starting to envisage a project with all my surplus laptop PSUs in a biscuit tin with your filter solution. Might even provide enough HT current for small TX as well as receiver?

[@Broken_Yugo]

Probably easier to follow one supply with a boost converter, then filter as demonstrated. Any time you float an isolated supply like that keep in mind you're stressing the insulation between the primary and secondary sections that much more, probably negligible with safe high quality power supplies and an increase of under 100V, but it is something to keep in mind.

[@glennrechnitzer8704]

There are tubes that run on 12 volts on anode and filament. look up space charge tubes for car radios. They were used in the entire radio except for the large germanium output transistor. Transistors were not good for high frequency in there begining.

[@MIKROWAVE1]

I am so old that I remember visiting a Motorola plant in Arcade NY, as a co-op student in 1978 and they were making car radios and alternators for Volkswagen and shipping them to Germany.

[@folkboatsailor]

In the Low pass filter diagram does the earth symbol mean the circuit should be connected to earth ground? Or maybe chassis ground? Or maybe it's just a zero voltage reference point? I always find that symbol very confusing but I don't know much about circuit diagrams.

[@MIKROWAVE1]

There is no right answer except in the context of the era and prevailing guidance of the company, entity or standard. Symbols have evolved and rules, color codes and standards are broken throughout the electronic age. I like to make schematics that look like they belong to the time period or country they represent, purely as art or ease on the eyes.

[@folkboatsailor]

@@MIKROWAVE1 OK Thanks Mike.

[@perryjones5500]

What about a rotary converter using off the shelf motors back to back or with gearing to generate HV from low voltage?

[@MIKROWAVE1]

Ah the rebirth of the Dynamotor!?!?

[@gretalaube91]

I need to take your "advanced" course, Mike. I wrestled with a few 12 volt switchers, trying to get 18 out, but never seemed to make it. Inductor Q? I think some are designed on the ragged edge, with the smallest L and C to get the V they want, but I don't know. Anyway, great! ATX gots lots o-good meat on them bones! W3IHM

[@db3501]

Can use plain old transformers, too. E.g. put a 110V/12V and a 24V/110V in series, gives you about 55V AC. Not much can go wrong behind a tiny weak 10W transformer...

[@MIKROWAVE1]

@@db3501 Ahh now we are talking about a really clever junkbox solution!

[@FarleyHillBilly]

@@MIKROWAVE1 240V/12V into 12V/240V gives you 340V iaolated 240V/6V into 12V/110V gives you 77V iaolated and 6V for heaters

[@Mold0vanin]

Буду признателен, если будете говорить чуть медленнее, чтобы русскоязычная публика могла вас понимать. Заранее благодарен. От себя добавлю, имею печальный опыт в применении импульсных источников питания в приемной аппаратуре.

[@MIKROWAVE1]

Мне нужно найти способ добавить субтитры. В мире не найдено волшебства, полностью фильтрующего переключение и мощность мультивибратора. С ресиверами всегда сложно.

[@Andrew_Erickson]

Wet finger test.

[@MIKROWAVE1]

This can work - once or twice?

[@SkyWire88]

Too advanced for me.

[@MIKROWAVE1]

Take a peek at some of my older videos!

[@mohinderkaur6671]

half wave rectified - light bulb in series, 1 diode. 1 capacitor. direct of the mains.

[@MIKROWAVE1]

Of course the guidance now is widowmakers are too risky. Use an Isolation transformer. The lesson here is if you manage to get this happy and safe - keep it plugged in to the same outlet! I learned the hard way and blew up a nice radio when I took the setup on the road.

[@mohinderkaur6671]

@@MIKROWAVE1 1 wire plug maybe. chasis directly grounded by other wire.

[@Broken_Yugo]

​@@mohinderkaur6671death trap, forget it.

[@blacksmock445]

@@MIKROWAVE1 I worked on TVs in the 1970s here in the UK. Live chassis, hopefully connected to the mains neutral, and 300mA series heater chain, across the 230v mains, for the tubes, was the usual setup. 2-pin mains plugs connected so that chassis was live was a constant hazard.

[@Capecodham]

Do you clean a vacuum tube with a vacuum cleaner? Can I use the filter from my furnace to reduce hum? Why do you use the term valves from a country we had to save their butts twice from the Germans?

[@MIKROWAVE1]

A sucky comment for sure Burt. Maybe this was tried in the old days. My Electrolux is the one to do it if it could be done.