What is this?

[Ian]

Hi
I so i got a tun of stuff from a friend today. So i was looking through all of it. and i have three of theese circuit boxes that have a bunch of stuff in them. but i have no idea what they are? here are some pics.


Here is some more info:
vacuum tube is a 2d21
The largest capacitor is 4mf, 50wvdc
The second largest capacitor is 16mf, 150wvdc
It has 2 pots. one has a knob, and one have a place to put a flat head screwdriver in.

If some one could please tell me what this is? I wont to know so bad.

[Mechatrommer]

this is by no mean offending OP, but there is already a sticky thread where you can browse all sort of unknown stuff and freely to post yours "whats this item". so for the purpose of education of newbieevblogger here the thread https://www.eevblog.com/forum/index.php?topic=2713.15 , so by reading the thread during free time, will avoid you from hassle of re-posting the same thing. but you still fre to create your own thread so about the OP question, i have no idea. it looks like an old ESR tester to me, but i dont know.

ps: i like thick book, alot of stuffs in one package

[Lawsen]

Most of us have at least an electronics trade school certificate, some are working the field, some are repair vending machines, and others have at least a bachelor degree or more.  I am unable to identify the circuit.  It has one vacuum tube, which makes it a 1950s to 1960s vintage.  It has a lot of knobs and switches mounted on a chassis.  To identify this circuit, you will need to find a schematic diagram, that might be sticker on the chassis or find someone near by who is an older person from that era who likes electronics, maybe an amateur radio club?  You could study the circuit by drawing a diagram yourself, because most vacuum tube circuits were point to point wiring, not impossible to draw like printed circuit boards.  Try drawing a schematic diagram of an Asus motherboard in your desk top computer.  That would be an impossible tasks, unless you worked in designing Asus boards for Asus.  Vacuum tubes are used for amplification or rectification.  This is your project.  It can be an instrument, or an audio amplifier, too.  We do not know. 

Lawsen

[saturation]

It looks like a single channel amp.  The pot is volume, and the screwdriver trim pot is for tube bias adjustment.  But you pics are so blurry hard to tell more.

[Ian]

i will try to get some better ones

[jimmc]

The 2D21 is a Thyratron  http://www.r-type.org/pdfs/2d21.pdf  (Valve approximate equivalent of a Thyristor) so it's not an amplifier.
That and the presence of a relay suggests a timer of some kind.

Jim

[saturation]

I thought that was a relay, not sure why it would be there for an amp, my fault for not checking the part #, its so easy to google it  .  A timer type device would explain why there are so many jacks in the rear.  Thanks a bunch for clarification.