A delightful hour spent watching a master. When I left school in 1956, I got an apprenticeship with Ediswan in the UK - as a potential valve engineer. As I trained in the various departments, I saw valve components - anodes, cathodes, grids, etc. - made on automatic forming machines, and their assembly into various types of valves from those for battery radios up to transmitter valves the size of a football. I was always fascinated by the processes involved, but never more so than when watching you, Ron, creating an example of an early version from scratch. Such skill!
As he said "Ok, it's a complete success" Given the fine detail, dexterity required to make something like this, I am blown away. True artisan at work..
Thanks for the videos that you make, it makes me feel alot better knowing that there are still people in sheds with skills and knowledge who enjoy making and repairing obscure equipment. Matthew.
Hello Ron, I‘m following as a german electronic engineer in retirement your channel since few years and are amaized about your technical skill and knowledge, especially in vacuum tube technology. I was dealing in my youngsters time with vacuum tubes and have the knowledge how to understand and handle it. This knowlede is compleately lost in the meantime by our young engineers. Your knowledge is on an outstanding level over a wide field and it‘s a pleassure for me to follow your channel.
And that just happened! Omg that is fascinating. The way I imagined douing a tube and the way you make it look like are miles apart. Cant belive ive watched a 1 hour long video on this subject and got this warm nice feeling like I somehow participated! Great job!
It's a shame your expertise is so rare to find. In a not too distant future it will be sorely missed, since so many old vintage equipment makes use of this bygone technology, and it will be neigh impossible to restore it to its old glory, except by making use of solid state equivalents. Thanks for sharing your knowledge and the video. It's a pleasure to watch
Yes, like the equipment that no longer exists to decode/display the Apollo series data. That data has been lost anyway even if it could be played back.
I'm hopeful that some people might start to learn glassworking and making vacuum tubes because there definitely seems to be a resurgence of interest in antique electronics. I collect and restore old radios as a hobby and I've just recently been learning to fix antique TVs. I've been coming across a lot more videos lately from people interested in antique electronics. I even saw a video from a kid showing a couple of tube radios he was working on! He was only about 15-16 years old!
I just started repairing old radios as a hobby, and youtube suggested your channel.. And I'm glad it did! What true craftsmanship! I look forward to each and every video!
All I can say is WOW and GEEE WIZ !!!!!! Fantastic work with glass !!!!! I worked for IBM in East Fishkill N.Y. and they had there own GLASS SHOP there where they made all sorts of Stuff related to tooling that held or surrounded the Silicon wafers during the different production steps!! I think there was about 30 maybe slightly more that worked in " The Glass Shop " in 320B building. It really is a LOVELY ART with many facet's They worked primarily with Quartz and Pyrex types of glass. This was quite the video !! Thanks for the memories !! John Bellas KC2UVN.
how you manage to keep calm dealing with all that glass and springy wire purgatory is beyond me. i am a pretty patient person when dealing with small stuff but watching you do this made my heartbeat rise! =D great work and thank you for showing us "youngsters" how it was done.
Ron, I've missed your teaching videos and was so glad to see not only a new one, but new ones for the past few weeks! You've got a well deserved following on here and want you to know it! Thanks Doug
I know this guy is amazing I don't think there's anything he cannot do when it comes to electronics I'll wait patiently for his videos thank you glasslinger for the education keep up the good work
This, like all of your videos are unique and fascinating. I don't know of anyone else doing what you do. Like most experts, you make it look easy. Thank you for returning to show us your magic.
Long time watcher, no time commenter here. These videos are sooooo addictive. I have an interest in tube hifi stuff ( I don't get into the tube v s/s argument, they're both good ), so the glass making/tube content is super interesting. Haha, you start watching, and all of a sudden, an hour has passed. Many thanks Ron for sharing your boundless knowledge. A happy and safe festive season to all.
*Can we set up a patreon to buy you a new camera and tripod? Your videos are works of art not found anywhere else on youtube but the poor grade camera rally cuts down on the fine detail that needed to see it* Hell make your own camera we know you have the skills. I hope you still don't have that GE camera that stops recording I would like to see you take that camera to the oxy actyl torch and smash it to bit* .
The camera is a Cannon I2, which is not a junky camera. The problem is my eyes! I can't tell when it is in focus. The auto focus doesn't ever focus on the nearest stuff so it is useless. I'll try to do better!
@@glasslinger You do Great with all of the videos, the patreon ideal is a good one though, has I am sure the parts / material's can't be cheap to replace. I would be happy to pitch in. Love your videos. A very Merry Christmas to you. and a Happy New Year. Bobby
I know how you feel with those moments like when you looped the filament. It's the most angry I ever get. When it's something simple like that it's just the worse. Btw, I actually gasped when it looked like you were about to snip the bottom rung of the plate whilst you were trimming the excess off. Amazing stuff. Beautiful finished piece, and nice performance for something with such a low surface area for the plate. I wouldn't have expected that to work so well. Thanks as always for sharing.
I'm glad to see that you're posting tube making videos again. I've tried making vacuum devices myself with a miniature oxy-propane torch and a 2-stage vacuum pump, but i have so far managed to build only a few glow tubes and light bulbs.
I'm glad to see that you are making more videos. I always hold my breath watching these since I imagine it is really easy to get one step wrong and break the entire tube.
I love these tube making videos you do... The radio restoration stuff is cool too but I've never seen anybody else ever doing the tube making stuff. It's just SO different from any other electronics stuff I see or do.
Your Videos always amaze me and I am always glued to them and as The E Lab said they are awesome. I think it would be really great to see the Pilotron you made built into something and see it doing it's stuff, that valve is a work of art and you are extremely skilled and patient. Thank you for your videos they are simply brilliant!
I could watch you're content for hours on end.when i see you have added new content i get excited,personally i don't care what camera you use it's doing its job well. you're one of my favourites along with eevlog,and Mr carlsons lab.keep up the good work educating us all.
Most of the knowledge of these vacuum tubes is lying in a box in the ground. Thank you Ron for sharing this knowledge and please let us know how to help you
Amazing. It is the first time I see a vacuum tube being made from scratch. I think it is a triode in which the filament serves as cathode. Long long time ago when I stated in electronics vacuum tube was all I knew. It is a masterpiece.
I just hit like automatically when I start watching your videos. Don't even need to think about it. Another great one, both with your mad glass skills, your expert level knowledge of ancient electronics all the way to modern, and your excellent instincts! Wonderful stuff!
Realmente nunca en mis 60 y pico de años había visto algo semejante además porque soy un fanático de los tubos. Mis felicitaciones por la simplicidad de la explicación y ya tienes un nuevo suscriptor. Un abrazo desde Uruguay de CX6DT.
I fined it fascinating to put wires in a glass sealed then vac it & flash the getter AND it works moving electrons around in it own little world sort of. great to see so many things come together to make it work!
Right so i watched the whole video first things first great job Ron! You really out did your self. Also thanks to you i have begun the long path to making my own tubes as well. found some diffusion pumps on ebay and some other such gear. On top of this thanks for the great info on your website as well you may be the only other person to do this! Alex.
It is an outstanding Masterpiece of work & human Ingenuity !!! During the video, I imagined how those people in the past have figured out how to make these things, starting from the poorly known -mostly unknown- (at those times) electronics science. I can also imagine what a nightmare would have been to have two identical tube characteristics to make commercial radios... I'm really glad to have had the chance to see this video of a nowadays LOST hand ability to make these things... Smartphones made all of us
The ultimate in home projects is make your own tubes. Probably more difficult would be to make your own transistors, starting with silicon sand and a few metals (or non-metals, arsenic).
Wow took me back a few years to the early eighties when I remember part of my computing and electronic engineering course talking about Fleming and De Forest and pilotrons, kenotrons and the importance in the emerging radio broadcasting technology. I was lucky in getting it all in my head having a grandfather who was a senior signalsman on Royal Navy battleships during WW2 who was in charge of the radios on those behemoths and he was a keen radio user before the war being enamoured by Marconi's work. He got me hooked as a kid by building from old scrap radios, little crystal radio sets and my brother and I could tap morse code to each other like little adventurers, he purposefully knowing kids and what they would do, set the range very low as he didn't want one of us sending SOS's all over the place and causing chaos (that did happen with a 1970's ITT "survival" radio that was aimed at young lads, problem was it had a very good shortwave transmitter and caused no end of problems here in the UK)
You made this look easier than it actually was Have no idea what a pilotron does but your making of it by hand was superb and a wonderful achievement a great job all round I would have broken the glass in any number of places you must have very steady hands
So super interesting, well made and in a perfect pace! I think that this video has to be one of the best I have seen this week! Thanks for sharing. :-)
Witam serdecznie ! Twoje filmy są dla mnie inspiracja. Czekam na kolejne z wielką niecierpliwością Więcej, więcej ... a najlepiej o renowacji europejskich starych odbiorników radiowych. Dziękuję Ci za dotychczasowe filmy i życzę wiele zdrowia Adam
Very nice! Just wondering what the plate current vs. grid voltage curve looks like for this tube. Will you be plotting that out sometime in the future?
I warmly welcome. Did you try to get a getter yourself, eg by induction melting of some metal alloy, eg nickel with barium oxide under argon atmosphere?
Videos like these are damn interesting. The guy also seems to really love what he's doing as well, which is great. I don't even mind the camera quality! Great, interesting, wholesome content
Excellent , nice work. Thanks for sharing .. I am so curious what effects the geometry/spacing has on the various electrical characteristics. You mentioned larger spacing = only HV ...
Amazing work. Such skills. It's beautiful how the glass responds. I kept saying to myself, as you wound the grid wires, "don't put your finger or thumb through the filament..." then, at the end, just as I started breathing again, you caught the filament with the end of the wire. D'oh! I thought that was the end for sure!
Fantastic video, for the vacuum pumping portion, is that just a rotary vane pump or is there a diffusion pump hiding somewhere? I'd love to know what vacuum level is required to do this, as I'm very seriously tempted to try.
OUTSTANDING,Enjoyable and telling so much about talent Sir,i would say thanks to the silicon era that made things easier,lots of thanks for sharing your experience and wonderful knowhow ,God BLESS.
A delightful hour spent watching a master. When I left school in 1956, I got an apprenticeship with Ediswan in the UK - as a potential valve engineer. As I trained in the various departments, I saw valve components - anodes, cathodes, grids, etc. - made on automatic forming machines, and their assembly into various types of valves from those for battery radios up to transmitter valves the size of a football. I was always fascinated by the processes involved, but never more so than when watching you, Ron, creating an example of an early version from scratch. Such skill!
Full time glassblower in iowa here, love your vids! keep up the great work- some of the finest content on the TH-cam.
As he said "Ok, it's a complete success"
Given the fine detail, dexterity required to make something like this, I am blown away. True artisan at work..
Thumbs up first, then sit back and watch video..
same for me
Yep, you know it’s going to be amazing!
It's the best way to keep from forgetting. On my PC I have an addon that auto-likes the video if it plays longer than 2 mins, but not on my phone.
Thanks for the videos that you make, it makes me feel alot better knowing that there are still people in sheds with skills and knowledge who enjoy making and repairing obscure equipment. Matthew.
I'm passed the stage of being amazed at prof' Ron's abilities, no doubt we will witness Ron split the atom here one day.
Uuu7u7777uiii8iiu una
Hello Ron, I‘m following as a german electronic engineer in retirement your channel since few years and are amaized about your technical skill and knowledge, especially in vacuum tube technology. I was dealing in my youngsters time with vacuum tubes and have the knowledge how to understand and handle it. This knowlede is compleately lost in the meantime by our young engineers. Your knowledge is on an outstanding level over a wide field and it‘s a pleassure for me to follow your channel.
Beautiful work Ron. As someone who collects tubes and restores radios, I absolutely love these videos.
And that just happened! Omg that is fascinating. The way I imagined douing a tube and the way you make it look like are miles apart. Cant belive ive watched a 1 hour long video on this subject and got this warm nice feeling like I somehow participated! Great job!
Yup! I also can't believe that I spent an hour watching a vacuum tube (tetrode?)made by hand.
Words fail me. Absolutely amazing! A very big thank you from London.
It's a shame your expertise is so rare to find. In a not too distant future it will be sorely missed, since so many old vintage equipment makes use of this bygone technology, and it will be neigh impossible to restore it to its old glory, except by making use of solid state equivalents.
Thanks for sharing your knowledge and the video. It's a pleasure to watch
Yes, like the equipment that no longer exists to decode/display the Apollo series data. That data has been lost anyway even if it could be played back.
I'm hopeful that some people might start to learn glassworking and making vacuum tubes because there definitely seems to be a resurgence of interest in antique electronics. I collect and restore old radios as a hobby and I've just recently been learning to fix antique TVs. I've been coming across a lot more videos lately from people interested in antique electronics. I even saw a video from a kid showing a couple of tube radios he was working on! He was only about 15-16 years old!
I just started repairing old radios as a hobby, and youtube suggested your channel.. And I'm glad it did! What true craftsmanship! I look forward to each and every video!
It's fascinating to watch someone craft a vacuum tube from start to finish, Thank you for filming it!
Ron, I am absolutely speechless. Ask anyone who knows me, that doesn't happen often.
All I can say is WOW and GEEE WIZ !!!!!! Fantastic work with glass !!!!! I worked for IBM in East Fishkill N.Y. and they had there own GLASS SHOP there where they made all sorts of Stuff related to tooling that held or surrounded the Silicon wafers during the different production steps!! I think there was about 30 maybe slightly more that worked in " The Glass Shop " in 320B building. It really is a LOVELY ART with many facet's They worked primarily with Quartz and Pyrex types of glass. This was quite the video !! Thanks for the memories !! John Bellas KC2UVN.
how you manage to keep calm dealing with all that glass and springy wire purgatory is beyond me. i am a pretty patient person when dealing with small stuff but watching you do this made my heartbeat rise! =D great work and thank you for showing us "youngsters" how it was done.
Amazing dexterity, awesome skills.
Ron never ceases to amaze with these skills and extreme patience! All the best to you, sir...
A great video Ron on how to make a wire pillotron keep up the great work and have a good day
Just came here from Cody's Lab and I am blown away... Your work is incredible. Thank you for sharing all of this with the world!
Ron, I've missed your teaching videos and was so glad to see not only a new one, but new ones for the past few weeks! You've got a well deserved following on here and want you to know it! Thanks
Doug
I know this guy is amazing I don't think there's anything he cannot do when it comes to electronics I'll wait patiently for his videos thank you glasslinger for the education keep up the good work
This, like all of your videos are unique and fascinating. I don't know of anyone else doing what you do. Like most experts, you make it look easy.
Thank you for returning to show us your magic.
This is the best thing I have seen on the internet this week. Awesome skills. Sadly, I am guessing, a dying trade. Respect!
That's some seriously intricate workmanship there
Ron, you are not just an engineer, you sir are an Arteeest!
What an EXCELLENT video, I wish I could have found your channel 60yrs ago !!!
Long time watcher, no time commenter here. These videos are sooooo addictive. I have an interest in tube hifi stuff ( I don't get into the tube v s/s argument, they're both good ), so the glass making/tube content is super interesting. Haha, you start watching, and all of a sudden, an hour has passed. Many thanks Ron for sharing your boundless knowledge. A happy and safe festive season to all.
I love your videos. I learn so much more watching someone do things and explain them at the same time. Thanks!
*Can we set up a patreon to buy you a new camera and tripod? Your videos are works of art not found anywhere else on youtube but the poor grade camera rally cuts down on the fine detail that needed to see it* Hell make your own camera we know you have the skills. I hope you still don't have that GE camera that stops recording I would like to see you take that camera to the oxy actyl torch and smash it to bit* .
Nooo, it should be restored as a thing of beauty
@@analogueavenue radiofun232 ftw!
The camera is a Cannon I2, which is not a junky camera. The problem is my eyes! I can't tell when it is in focus. The auto focus doesn't ever focus on the nearest stuff so it is useless. I'll try to do better!
@@glasslinger you're doing great!!
@@glasslinger You do Great with all of the videos, the patreon ideal is a good one though, has I am sure the parts / material's can't be cheap to replace. I would be happy to pitch in. Love your videos.
A very Merry Christmas to you. and a Happy New Year.
Bobby
I know how you feel with those moments like when you looped the filament. It's the most angry I ever get. When it's something simple like that it's just the worse. Btw, I actually gasped when it looked like you were about to snip the bottom rung of the plate whilst you were trimming the excess off. Amazing stuff. Beautiful finished piece, and nice performance for something with such a low surface area for the plate. I wouldn't have expected that to work so well. Thanks as always for sharing.
I have an old radio one with the “glowing eye” and to think all of those old tube radios were made like this......just awes me.....your a master maker
I'm glad to see that you're posting tube making videos again. I've tried making vacuum devices myself with a miniature oxy-propane torch and a 2-stage vacuum pump, but i have so far managed to build only a few glow tubes and light bulbs.
I'm glad to see that you are making more videos. I always hold my breath watching these since I imagine it is really easy to get one step wrong and break the entire tube.
You're like the Bob Ross of homemade vacuum tubes. Love watching these videos.
I love these tube making videos you do... The radio restoration stuff is cool too but I've never seen anybody else ever doing the tube making stuff. It's just SO different from any other electronics stuff I see or do.
Your Videos always amaze me and I am always glued to them and as The E Lab said they are awesome.
I think it would be really great to see the Pilotron you made built into something and see it doing it's stuff, that valve is a work of art and you are extremely skilled and patient.
Thank you for your videos they are simply brilliant!
Good to see the glass lathe spinning again. This is an art that’s pretty much gone. Thanks for another great video Ron! Long time subscriber here.
Absolutely amazing. Your videos are an inspiration that anything is possible.
Ron-
It's been a long time since your last 'tube' video. But the wait was worth it. You make it look so easy. Take care of yourself.
I could watch you're content for hours on end.when i see you have added new content i get excited,personally i don't care what camera you use it's doing its job well. you're one of my favourites along with eevlog,and Mr carlsons lab.keep up the good work educating us all.
Thank ;you so much! I can't get enough of these glass / tube videos. Please keep them coming!
Amazing, unique video again. Is a documentary.
Most of the knowledge of these vacuum tubes is lying in a box in the ground. Thank you Ron for sharing this knowledge and please let us know how to help you
Amazing. It is the first time I see a vacuum tube being made from scratch.
I think it is a triode in which the filament serves as cathode.
Long long time ago when I stated in electronics vacuum tube was all I knew.
It is a masterpiece.
Cat whisker detector at the end says, "Good job!"
Glad to see you're still making tubes!
I love your 2 part videos on all of your home-made equipment.
You Fella ARE An Amazing Craftsman !
WoW . Massive Respect From Birmingham England UK
I’d love a bulb like this. Pure functional art.
This took a lot of work! Well done!!!
The most amazing content on TH-cam. Love, Love Love!!!
I just hit like automatically when I start watching your videos. Don't even need to think about it. Another great one, both with your mad glass skills, your expert level knowledge of ancient electronics all the way to modern, and your excellent instincts! Wonderful stuff!
Realmente nunca en mis 60 y pico de años había visto algo semejante además porque soy un fanático de los tubos. Mis felicitaciones por la simplicidad de la explicación y ya tienes un nuevo suscriptor. Un abrazo desde Uruguay de CX6DT.
You are legendary.
Amazing work as always!
You are a wizard! This is therapy to watch! Thank you, Ron!
Glass linger you are good at restoring vintage radios and vintage TVS my friend 🎉🎉🎉
Just.... Wow man! Your skills are amazing. Great to see you back at making tubes! Thank you.
Pure Magic, Look forward to your next enlightenment, You are a Master..
I fined it fascinating to put wires in a glass sealed then vac it & flash the getter AND it works moving electrons around in it own little world sort of. great to see so many things come together to make it work!
Right so i watched the whole video first things first great job Ron! You really out did your self.
Also thanks to you i have begun the long path to making my own tubes as well. found some diffusion pumps on ebay and some other such gear.
On top of this thanks for the great info on your website as well you may be the only other person to do this!
Alex.
fantastastic craftsmanship and knowledge thank you for sharing it. Alway's enjoy watching your video's.
It is an outstanding Masterpiece of work & human Ingenuity !!! During the video, I imagined how those people in the past have figured out how to make these things, starting from the poorly known -mostly unknown- (at those times) electronics science. I can also imagine what a nightmare would have been to have two identical tube characteristics to make commercial radios... I'm really glad to have had the chance to see this video of a nowadays LOST hand ability to make these things... Smartphones made all of us
Amazing Ron.
The ultimate in home projects is make your own tubes. Probably more difficult would be to make your own transistors, starting with silicon sand and a few metals (or non-metals, arsenic).
I didn't think it was even possible to make working homemade vacuum tubes. What this guy does is incredible!
Wow took me back a few years to the early eighties when I remember part of my computing and electronic engineering course talking about Fleming and De Forest and pilotrons, kenotrons and the importance in the emerging radio broadcasting technology. I was lucky in getting it all in my head having a grandfather who was a senior signalsman on Royal Navy battleships during WW2 who was in charge of the radios on those behemoths and he was a keen radio user before the war being enamoured by Marconi's work. He got me hooked as a kid by building from old scrap radios, little crystal radio sets and my brother and I could tap morse code to each other like little adventurers, he purposefully knowing kids and what they would do, set the range very low as he didn't want one of us sending SOS's all over the place and causing chaos (that did happen with a 1970's ITT "survival" radio that was aimed at young lads, problem was it had a very good shortwave transmitter and caused no end of problems here in the UK)
Wonderful work, real craftsmanship.
You are my idol! Incredible habilities. You are the only guy I know that can make his own light bulbs 😸
Thanks love the tube ever thought about selling the homemade tubes as a mantle piece or a look pretty piece?
You sir are an artist
You made this look easier than it actually was Have no idea what a pilotron does but your making of it by hand was superb and a wonderful achievement a great job all round I would have broken the glass in any number of places you must have very steady hands
Good job i am full of admiration for your job ! Good vidéo
So super interesting, well made and in a perfect pace! I think that this video has to be one of the best I have seen this week! Thanks for sharing. :-)
Liquid was water vapor from the torch condensing on the cool carbon I suspect.
Absolutely fascinating and incredible skill! I look forward to watching more videos and wish I had the ability to do the same work!
I'm so far from doing the tenth of it that I watch this video being hypnotized.
Witam serdecznie !
Twoje filmy są dla mnie inspiracja. Czekam na kolejne z wielką niecierpliwością Więcej, więcej ... a najlepiej o renowacji europejskich starych odbiorników radiowych.
Dziękuję Ci za dotychczasowe filmy i życzę wiele zdrowia
Adam
Oh yeah, I was missing your glassblowing stuff Ron, nice to see you back at it.
Very nice! Just wondering what the plate current vs. grid voltage curve looks like for this tube. Will you be plotting that out sometime in the future?
Very nice Ron. Fishing those 4 wires into the correct base pins must be fun.
The dexterity he command's is incredible. I would love to do some work like that, and the muscle memory would take a while.
If I could like this video 1000 times I would.
Pilotron Cat approves of your work. Wonderfully done, sir!
I warmly welcome. Did you try to get a getter yourself, eg by induction melting of some metal alloy, eg nickel with barium oxide under argon atmosphere?
YAY!!!! Love your tube recreation videos :-)
@glasslinger beautiful work as usual. Keep em coming.
Fascinating! Amazing what you do, GL! Thank you.
I really enjoyed that. Thanks very much for sharing your skills and for the video.
INTELIGENTE DEMAIS !!! CONGRATULATIONS FRIEND !!!!
1 DOS VÍDEOS MAIS INCRÍVEIS QUE JÁ VI !!!!!
another amazing informative video! Greetings from New Zealand, please keep up the great work and thanks for sharing the process with us.
I always enjoy your tube videos, great to see another. Very cool.
Never heard you get pissed before...lol. I like it
Videos like these are damn interesting. The guy also seems to really love what he's doing as well, which is great. I don't even mind the camera quality! Great, interesting, wholesome content
Excellent , nice work. Thanks for sharing .. I am so curious what effects the geometry/spacing has on the various electrical characteristics. You mentioned larger spacing = only HV ...
Amazing work. Such skills. It's beautiful how the glass responds.
I kept saying to myself, as you wound the grid wires, "don't put your finger or thumb through the filament..." then, at the end, just as I started breathing again, you caught the filament with the end of the wire. D'oh! I thought that was the end for sure!
Fantastic video, for the vacuum pumping portion, is that just a rotary vane pump or is there a diffusion pump hiding somewhere? I'd love to know what vacuum level is required to do this, as I'm very seriously tempted to try.
Fabulous work there! I'm truly impressed. *bows humbly*
OUTSTANDING,Enjoyable and telling so much about talent Sir,i would say thanks to the silicon era that made things easier,lots of thanks for sharing your experience and wonderful knowhow ,God BLESS.
Great job Ron
Glass linger this is awesome you make a wire pilotron is awesome my friend 🎉🎉🎉🎉
your the best, wonderfull work