Crawls Backward (When Alarmed)

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World's Smallest Tube Geetar Amp?

Whilst going through my pile of tube junk that I have stored up for moments like these when I am between projects, I discovered this. It seems like it was a phono amp from a "portable" record player. I got it from the dreaded auction site known as e*b* for like 99 cents. It's kinda tiny, but let's take a closer look.

At the time I bid on it, I thought, "hey, I can make a geetar amp outta that thang!"

So here we are. Lets make a geetar amp outta it!

Looks like we have the ubiquitous 50C5 output tube, produced by the zillions and found in billions of late 1950s - 1960s American AM radios, clock radios, record players and even cheap geetar amps. We also have a super tiny output transformer; won't get much bass outta that. Upon further inspection, we have one other tube socket - 7 pin and EMPTY. Somebody probably figgurd that tube was worth a fortune and sold it online separate from the amp. Weren't they surprised when they didn't get 2A3 money for it! (But...but...it's OLD and it's a TUBE - it MUST be worth a fortune!)

FWIW, the date codes on the pots are 1960. So there you have it.

This thing is tiny, let me tell you. You get an idea from the underneath. And after looking at it a bit and even starting to draw a schematic I see We Have Issues. Namely, it's really tiny. And secondly, wherever the rectifier was, it was elsewhere in the device - it was not on this chassis. But oddly enough, the filter caps were (see the can).

All of this leaves us with some choices, does it not? We can put some of zee diodes (probably one 1N4007 will do it for a real simple half-wave rectifier) in it and restuff the can or even wedge some new electrolytics under the chassis for a power supply. And use the existing sockets for an input tube such as a 6c4, and then keep the ol' 50c5 as the output. Ain't no way an input socket can fit anywhere on this thing...if I didn't say this before, it is TINY. I mean really small.

Or, we could toss it aside and find something else to play with and strip this thing for parts. But while I ponder, I shall look up some schematics of cheap (Kay, Harmony, etc) amp schematics and perhaps get some in-spi-ray-shun.

Meanwhile, I leave you with a closeup of the way the chassis 'cage' was attached. Gotta love them tabs - anything to save a coupla pennies on some fasteners.

 
 
 
 

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