Low Voltage Regenerative Receiver Project - Part 1

[@PeopleAlreadyDidThis]

This’ll be fun. Had to laugh at a memory this jogged...when I was a kid, I powered the heater on some miniature triode and played a portable cassette player through the tube-with zero plate voltage. I got a tiny, weak, horribly distorted output that I’d listen to for hours just because it had traversed that tube. A little miracle in a bottle. That was as much fun as the first working circuit I built.

[@MIKROWAVE1]

I have no idea what you did, but we should name the effect before someone steals the intellectual property!

[@user-dh1kq3eh8q]

Bravo doktore za elektronsku. Lepo sve objašnjavaš. Svaka čast. Yong i Cooking recepti.

[@littlebear5219]

Looking forward to the complete design I love watching KZbin for your interesting circuits.

[@MIKROWAVE1]

I will be prepping the wood, drilling some holes in a front panel and working out a simple layout this week.

[@jasholden9741]

I'm glad that you are helping keep the old homebrew radios alive. Back during the 90s I was in a Yahoo Club that designed and built very high performance Crystal Radio Sets. From that, I also built some tube radios....regen, reflex and others from the period before the Superheterodyne All American Five came on the market. The AA5 took the market by storm and after 1932, the earlier designs became academic except for some special uses. My fav regen radio runs a Type 30 tube with a pair of variable caps for regen control. There are still tons of small value trimmer caps available on Ebay to use for the fine tuning cap. It makes it easy to ride the edge of regeneration. I was never happy with designs that used a Pot to control regeneration. Despite that, I think that over time most homebrew regen radios did use a pot for regen control, because it was cheaper.

[@MIKROWAVE1]

Wow you have seen the whole cycle of radio development!

[@houseblacksmithing9836]

I have a regenerative that runs on 12v, I believe I used a couple 12AU7s in it. One for the regen and one for the audio amp. Works well, if a little quiet. I look forward to the rest of the series, I know when i saw you had put up a new video my first reaction was "AWESOME!"

[@MIKROWAVE1]

In Part 4, I want to try 12V on the Regen, with a few different tube types. 12AU7, 6C4 and the 6BF6 - OH and let's pull the tubes and stick in some FETs.

[@Broken_Yugo]

Last spring I did a similar build more or less for free, all from junk I had. One tube (MRL circuit) into a set of computer speakers through a capacitor, used a plate load resistor without trouble. The 12BA6, tube socket and tuning cap (with big wheel knob for easy tuning) came from a extra grungy AA5 clock radio not worth restoring I think I paid $5 for, the rest, including parts for the homemade few pf antenna coupling variable cap, came from a junked boom box and various junk appliances. In lieu of a proper coil socket or forms I used alligator clips and pill bottles. It liked 20 some odd volts of B+, picked up stations from broadcast band up to about 10mhz (WWV on a good night) and seemed limited by the antenna I came up with, 60 ft of wire sloping from about 8 to 20 ft, more than anything. One can totally build simple tube receivers cheaply without much of a junk box, that was the first radio I ever built.

[@MIKROWAVE1]

Wow that is an awesome feat of junk magic!

[@Broken_Yugo]

@@MIKROWAVE1 That's what I like about the regen, everything critical is by design adjustable, or up to the builder, lead dress, layout, etc. I think I'll center the next one around the back/antenna of that AA5, with a tickler on a stick like an old Crosley regen.

[@acestudioscouk-Ace-G0ACE]

I'm hooked already! I've always wanted to work with valves... tubes (sorry I'm from the UK!) and this project is a safe introduction.

[@MIKROWAVE1]

Standby for fun.

[@franpin3924]

Very good. Thank for you video friend.

[@charleswells9682]

Love this. I'll be building it. I have 2 cheap standoff options that I've used successfully. First is a section of polyethylene tubing - bought a foot for 29 cents. Just cut it to length and run the wood screws through it. (Used this method for Bob Heil's Pine Board Transmitter; worked very well.) The second is the white polyethylene/polypropylene cutting boards that were being discarded from the kitchen. Cut into 1/2" to 3/4" squares, drill a hole and there you are. The squares can be stacked to make various heights. Just some thoughts; I like to build with as much built at home as possible.

[@MIKROWAVE1]

That would make a good video - a radio built from your kitchen clutter alone...

[@MIKROWAVE1]

Eduardo asked about the Schnell type regenerative receptor - Any time that a link coupling method is used either for input coupling from the antenna or as a variable coupling method for feedback, as with a regen, you end up with a smoother and more predictable control. But it is hard to manage on multiple bands, so the plug in coil and throttle capacitor is more common.

[@MIKROWAVE1]

As usual. I usually am treading on ground that had been trod before and it becomes a learning experience!

[@jamesmoffat9754]

12 volts on the plate, you got my interest. Also I will be following your design process.

[@MIKROWAVE1]

Of course nothing is for free. Less voltage means less gain and less audio volume. But operating a regen starved is an old trick for getting smooth regeneration control.

[@stephenwilliams5201]

Got that right. A stepper is not good for b+. Even a vibrator ps for autos was noisy. Good show om.

[@cooker4409]

damn it....my bad Mike.....I saw the first one.....will wait for #3 video.....thanks, Mike....

[@MIKROWAVE1]

Part 3 is up!

[@cooker4409]

I'll be going thru my junkboxes this winter.....I built stuff YEARS ago.....but I inherited some O-scopes, sig. gen's., etc., that I will be checking out this winter....jolly good.....got plenty of wood for bases just for stuff like this.....even got some variable caps....some I dunno what is, but have multiple "gang" sections even....got chokes, too, and lotsa parts.....diodes, caps, trans., etcetera.....really needs to be gone thru.....and done something with....let's see whatcha come up with....

[@MIKROWAVE1]

Wow - a nice junkbox indeed. And safely stored away.

[@nazmi3126]

You sir are a true Elmer! I just discovered your channel and your videos are incredibly descriptive. I can actually learn something from your videos and you've greatly sparked my interest in Crystal radio sets and building. Thank you, 73!

[@MIKROWAVE1]

Oh No - I must be getting old. He used the ELMER tag.

[@lomgshorts3]

Oh, I agree! So many people have forgotten tube technology (except for in high power r-f amplifiers) that millions of NOS tubes remain on the shelves. I have several sets of tubes for all my tube transmitters and receivers and they were CHEAP! So when someone comes on KZbin to tech how to build with tubes, they are truly an Elmer!

[@julianvalenti]

Hi! I have to remove the dust of my tube's box. There are 3 miniature single triodes with double diode but no inscription wit the name. May be 12at6 or 12av6 because there are some like 50c5 and 35w4. I am waiting for the second part! Thanks you for share it!

[@MIKROWAVE1]

Tubes were so advanced and well manufactured, that even by the 1930's, they could take ridiculous abuse and still function after 75 years.

[@julianvalenti]

@@MIKROWAVE1 I can say you are right. When I was young in the 90's I make my first am transmitter of a 6dq6. In the adjust procedure at a fail on care or attention the plate become red and hot like a chili pepper and were enough just to retune the plate to stop the problem and the poor tube stills working fine. Try this with an rf transistor without cry for a week later!

[@MauriatOttolink]

@@julianvalenti When I was an apprentice, my boss didn't like transistors... He said "They just sit there with three bloody legs and say 'I won't work. I won't work. I won't work!' "

[@julianvalenti]

@@MauriatOttolink Hi! We really know that transistors are te best choice to make engineering an develope new products. But in the experimenting and playing with circuits we can use tubes as alternative. Thanks to share with us!

[@jerryuhte1284]

Way to go Mike, as usual this should be a good one , i have been following some of these L V Regens , especially the one from a French Ham, Call ? he is using 4 Russian tubes ( Old military ) , appears to work great ! They are cheap on e Bay ! Good luck , looking for the next video ! 73, Jerry K9UT ps I am working on a D C Recvr from W7ZOI/ W1FB now !40/80 M

[@MIKROWAVE1]

Wow good luck on the Direct Conversion radio. They are a lot of fun. W7ZOI/W1FB are godlike entities.

[@Chris_Grossman]

I have an identical pair of headphones I have had since about 1969, and they were old then.

[@MIKROWAVE1]

When I see an old dirty set in a box, at a flea market I can not resist trying to bring them back on line.

[@DAVIDGREGORYKERR]

Sorry this will make for a unit that will be very safe. Philips Raytheon (5840W) Micro vacuum tubes will also work and no socket is needed as the wires can be wrapped around the screws before being tightened up if you cannot get that type then KORG 6P9 tube will also work but is sightly microphonic, if you use 47,000uf 25V WKG Electrolytic capacitor as well as a ceramic capacitor should keep the hash down.

[@MIKROWAVE1]

I was thinking 100 to 220 ohms and then a 1000 uF and a 0.1 to ground. After the fils.

[@mohinderkaur6671]

12au7 is quite good for low voltage, 12bh7 is even better. any hi-gm pentode connected as triode will work well too.

[@MIKROWAVE1]

Once I get it working (please work), I will substitute a few valves for the 12AV6's, and we shall see some interesting effects, I am sure.

[@Mold0vanin]

отличное видео, спасибо

[@sm3981]

10:47 🇧🇷👍

[@MIKROWAVE1]

Regens are fun. Applying Low Voltage to high voltage valves is fun and safer, but unpredictable, since we are trying to use the deivice in uncharted territory.

[@tomyyoung2624]

YES! YES! YES!!!!! the tonight!

[@adzbasslines268]

Looks like many 12AV6 prices have just gone through the roof....

[@MIKROWAVE1]

This is funny. When I wanted to build the Morgan Regen from the book as a kid, the 6BF6 was specified. It was not a very common tube compared to the12AV6, 6AT6 or 12AT6, which I already had a box of and would have worked fine. So my dad takes me down to the TV service shop where the guy charged 5.95 in 1972.that is 37 dollars in 2020 value.

[@lomgshorts3]

I wish a regen receiver that has no semiconductors that are EMP sensitive. I have a very good reason for this. Whether the EMP comes from the Sun, or "another source", I want the receiver to stay working no matter what.

[@MIKROWAVE1]

Any receiver in a metal case that is properly bonded (a Faraday Cage) and not connected to an antenna will be safe from EMP. So store it until you need it. EMP typically takes out the first stage only - the one connected to an antenna.

[@lomgshorts3]

@@MIKROWAVE1 Well, what I worry about the most is an EMP attack from Iran or North Korea because they are capable of such. I have a small Faraway cage I built for just a C Crane radio and two Yaesu handhelds for local comms, but I'm going to build a bigger one soon. But I do not worry about my National HRO-5TA-1 and my Viking Valiant II tube only radio is that they do not use transistors or diodes. No semiconductors means no sensitivity to an EMP no matter what the source. I'm building three tube regeneration shortwave receivers and a crystal radio for last chance info collection in case I get caught by a late EMP a week after I open up my cages. Call me a worry wart, but backup equipment is necessary to me.

[@MauriatOttolink]

Oh..Is throttle regen. better than voltage control? I never used anything other than throttle and felt that I should really be using voltage. I have an enviable junque box of caps collected over many years so I'll stick with throttle. At 80 I'll put the rest of them in my will to MIKROWAVE1.

[@MIKROWAVE1]

For triodes, Throttle or Variocoupler seem unbeatable. There are some cascode circuits that claim to work well with voltage . For pentodes, a variable voltage off a well regulated source to the screen works very well if the bypass is chosen carefully.

[@esecallum]

I built one.

[@MIKROWAVE1]

Did it play? Did you get a shock?

[@jamesmoffat9754]

I managed to salvage a toroid from a switch mode power supply. My LCR meter says it's 100 mH at 10 khz. I'm not sure that's correct but I will try it anyway. Not for nothing but kitsandparts.com sells an FB-31-1020 toroid for $4.50 American bucks and 10 feet of wire for a dollar. 30 turns of wire will give 5 mH at 1 MHz according to their calculator. This might be an option for people who don't have an old tube type radio to sacrifice.

[@MIKROWAVE1]

Worth a try!

[@iceberg789]

i am not sure where to get the audio transformers, but can i use ac power transformer ?

[@MIKROWAVE1]

It depends. The best or highest impedance types will be small. For instance a filament transformer say 6.3 VAC at 1 A from 230 V mains. That mains side will have a high reactance at audio frequencies. This is a good experiment, and something to try in the video.

[@iceberg789]

@@MIKROWAVE1 i see, so small o/p voltage transformers to be checked, thanks.

[@diobrando2160]

Can't the 12au7 heaters be wired in either series or parallel too?

[@MIKROWAVE1]

Yes which makes it very useful. But here is a question: What if you only hook up the center and one side of the filament?

[@diobrando2160]

​@@MIKROWAVE1 Does the other filament/cathode get heated by the first?

[@MIKROWAVE1]

@@diobrando2160 Actually there are two independent triodes inside. So only one gets juice. This is a way to turn off one side of the tube.

[@diobrando2160]

@@MIKROWAVE1 Ah, so the filaments are completely separate then. Also do you have videos on beginner valve amplifiers?

[@technophile01]

hi, why don't you work with transistors !? They are - unlike triode lamps - very widespread and young people (who follow you) with limited financial means can recover them on old cards ... thank you

[@MIKROWAVE1]

That is the magic part of this video series. We are going to unplug the tubes and put in transistors into the sockets at the end.

[@technophile01]

Thanks. I am waiting for it..my englich is'nt perfect😄

[@tonychristoph1063]

@@MIKROWAVE1 good idea

[@matid8453]

i want buy tube lamp 6n2p, 6n1p and 6ż1p and make too regenerative receiver

[@MIKROWAVE1]

Sounds good! Those are fine valves.

[@MauriatOttolink]

Slip of the tongue.."wiring cathodes in series or parallel for 12 or 24 volt operation?" Heaters?

[@MIKROWAVE1]

Yup!

[@user-dh1kq3eh8q]

Obavezno pravim po t vojnoj šemi. 73 yu1qg

[@MIKROWAVE1]

Vojni višak čini fine radije!