Germanium Transistor Haul

Discussion in 'The Stomp Box' started by ArcticWhite, Jul 10, 2020.

  1. ArcticWhite

    ArcticWhite Tele-Holic

    Posts:
    889
    Joined:
    Apr 14, 2009
    Location:
    Portland Oregon
    The other Germ thread reminded me of this stash of transistors I pulled out of a 1955 Gulbransen organ about eight years ago.
    I'm mostly an amp builder/tweaker, but I did build a distortion pedal from a kit 20 years ago.

    There are two sizes. Half are GE and the others all have a splotch of paint applied by the organ maker to obscure the brand. Perhaps there was a contract dispute or something.

    Anyway, tell me what I have here?

    20200709_220701.jpg 20200709_220913.jpg 20200709_220633.jpg 20200709_220637.jpg
     
  2. tubegeek

    tubegeek Friend of Leo's

    Age:
    59
    Posts:
    2,480
    Joined:
    Jan 31, 2020
    Location:
    Brooklyn, NY
    I see a GE logo.

    I built a couple Fuzz Faces with GE Ge's.
    2N525 is the type I have a handful of.
    They sound great, to me!

    20191107-015511.jpg
     
    ArcticWhite likes this.
  3. ArcticWhite

    ArcticWhite Tele-Holic

    Posts:
    889
    Joined:
    Apr 14, 2009
    Location:
    Portland Oregon
    Do you have a schematic for that one? And can you explain that board? Looks like everything soldered to copper sheets. What's the trick?
     
  4. tubegeek

    tubegeek Friend of Leo's

    Age:
    59
    Posts:
    2,480
    Joined:
    Jan 31, 2020
    Location:
    Brooklyn, NY
    Fuzz Face, using negative ground, I followed the second schematic here:

    http://www.muzique.com/lab/fuzzface.htm

    [​IMG]

    I made one modification: I added an extra stage of power filtering because I got an oscillation, which I had been warned about in this "flipped" power supply FF. So I think it was maybe 100 ohms in series (the schematic says 10 but I think it was 100) with the 9V and 22uF or 47 uF from 9V to ground. That was enough to prevent any problems.

    fuzzfaceposwfilter copy.jpg

    The photo shows my example of a style known as "dots and dashes" or "Manhattan style." It's something RF geeks, ham radio ops etc. often use. (The photo was taken before the power supply mod was tacked on.)

    https://aa7ee.wordpress.com/tag/manhattan-construction/

    You start with a sheet of copperclad PCB material, copper side up. This is your ground plane, and any ground connections you need get soldered directly to it. I use a set of chain-nose pliers to make a little solder loop in the lead so it attaches securely to the flat surface.

    Any junctions that AREN'T grounded get a little chunk of cut-up copperclad board, a little dot or strip that you can cut out with an Xacto saw or mini hacksaw. Whatever meets at that junction gets soldered directly to the chunk. The chunks get glued down to the base piece. I use crazy glue gel and press down hard and wait maybe 20 seconds. If it comes up later I just crazy glue it again. I know that there are some who use 5 minute epoxy after pre-planning all the chunk locations, this seems like it'd be a good alternative once you have everything worked out. The crazy glue can be iffy.

    Supposedly you can use a paper punch to pop out a bagful of dot shapes - I found I had more use for strip shapes so I haven't really pursued that tip.

    Your layout can be very much in the shape of the schematic, and with a touch of pre-planning can be very compact. You can double-deck the cut chunks too, to gain some 3D flexibility if you paint yourself into a corner. I have found this style to go together VERY quickly and is not too slow to replicate if you want to do additional units.

    The omnipresent ground plane is very good for low noise and RF rejection. It's a great method and I like it a LOT for simple thrown-together circuits. I think it's a great way to make high gain fuzz pedals turn out well, and it's more immediate than designing a PCB, which I find super tedious.

    A Somewhat Different Fuzz:

    asdfmanhattan2.JPG

    A sweet RF circuit build by the ham radio guy at that link I put up above:

    manhattan style.jpg
     
    Last edited: Jul 10, 2020
    ArcticWhite likes this.
  5. ahiddentableau

    ahiddentableau Tele-Meister

    Posts:
    257
    Joined:
    Jul 8, 2018
    Location:
    Middle of Nowhere
    Don't think there's any way to know the specs of those transistors from sight as there aren't any markings and GE made lots of different transistors. However, for guitar circuits that almost never matters. The only things that really matter are the characteristics in a simple audio type circuit: gain (hfe) and leakage current most especially. If you want to build a fuzz face transistor selection really matters, so you've gotta know how to test them.

    Fortunately, you can build a simple circuit to test the lot--R.G. Keen (the man, the myth, the legend) wrote a great little article years ago all about it (I think it was on GEOfex). It's a dead simple build and works great. Just make sure you give each unit time to settle and cool down after you place each unit in the sockets of the testing circuit. Even the small amount of heat that you end up transferring to the unit from your fingers when you handle them is enough change the readings in a significant way.

    Here's the link:
    https://tagboardeffects.blogspot.com/2012/08/germanium-transistor-tester.html

    Nothing like a good fuzz face. Greatest pedal ever!
     
    tubegeek, ArcticWhite and kcarlos like this.
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.