vacuum tube

Please help. Considering building a vacuum tube tester from an old magazine design. Parts seem to be an issue because of the 1950’s era age of the design. I want to replace a Sarkes Tarsian Selinium voltage doubler Rectifier part # 78D. Is there a modern day equivalent to this part?

The idea: To "re-purpose" V2 in that V2b (cathode follower) becomes the "added" gain stage between V1b and V2a. This is achieved via N-Mosfet source follower replacing the cathode follower. In doing some reading, thinking and simulating (not yet tinkered), I have arrived at what I think might...

I have a hybrid guitar amp that has a single 12ax7 in the preamp section and a class A-B solid state power amp section. I've been using it only as a power amp (I connect an external preamp to the "return" of the effects loop, completely bypassing the integrated preamp) and I recently noticed...

Hi all, I have a 807 vacuum tube and I want to make a CW RF amplifier with it. I am thinking of using transistors in pre amplifier and 807 as final power amp. I have only one tube so I cannot make push pull amp. First of all I need to know if it will be possible to make such RF amplifier. If...

Hi. I have recently gotten my hands on what I think is a very old radio: I am interested in how this device works. Inside the case is, among other things, a black cylinder containing some circuitry and on its side is a schematic: I have tried making a hand drawn copy: I am having a hard time...