What does a leaky germanium transistor sound like?

[vanessa]

What does a leaky germanium transistor sound like?

[formerMember1]

not sure, but from what i hear, it sounds unbiased, cuz even though you bias it, it is unstable and easily changes,  and also noisy/hissy.

don't know what else....

  Why?  Do you have a problem with your Ge fuzzface you built recently?

[vanessa]

Yes a Ge Fuzz Face this time. But I tested for leakage and it was low. The sound is like this.

If the pedal is on I can hear a light static sort of sound in the background, not very noticeable but there. And even at lower volumes I can get micro phonics very similar to a bad tube in an amp.

I A/B it against another Ge Fuzz Face I built. It too is noisy but not like this.

[MartyMart]

Try a "Rockface" ( recent build posted ) It's the most "stable" FF that I have
and I could only make it go "wierd" by blasting it with a hair dryer !!
I've tried several pairs of transistors in it ( some random un-checked ) and it works well
with almost everything  ! 
Or how about the old "diode" temp stabillity mod ?

Marty.

[vanessa]

So would it be correct to say that what I'm experiencing is not a leaky ge transistor?

My guess is that a leaky transistor sounds like an un-biased ge transistor, one that goes in and out of bias. Sounding like its clean loud to mosquito fuzz/off.

My issue my be just a noisy transistor? Or maybe just in my head...

[petemoore]

   But I tested for leakage and it was low. The sound is like this.
  That test should be conclusive as to a Ge units leakage, if it's not leaking, it 'shouldn't be noisy.
  If the pedal is on I can hear a light static..if the Q's are socketted, try another transistor.
 

[vanessa]

It stinks, I did not socket them. It's not for me it's for a friend of a friend and I really have this thing in the back of my head that they will fall out some day. I know I can put some removable silicone glue but I'm just paranoid.

I asked the question for two reasons. One I really don't know, I've been lucky to get good transistors that have low leakage and are in the right ranges for projects I was working on at the time.

Two, I felt it would be cool to have this in the archive as a searchable question. When you’re working late at night just getting by on coffee and you run into a problem, there's not a lot of help available to you. Even on this forum most people are asleep.

[mac]

The leaky transistors I tried in a fuzz face sounded (can' find the words in english...) out of focus, the distortion being less intense and muddy but no hiss or noise ( I biased them properly ). In other pedals I tried, the differences between leaky and not leaky ones varied from small to minimun. In the last case, the bias were a voltage divider type with the emitter resistor being half the collector resistor, what makes the arrangement temp and hfe stable. Don't ask me why...
About stability, all I can say is that a leaky transistor stays steady at constant temp. Can't tell if variations in temp will affect it more than to a not leaky transistor. Probably it will. Did not test them.
Well, this is true for my very leaky AC176, AC187K, Sanyos SD72K and others above +500uA. I guess that people having better or worse quality transistors, but leaky, may say different things...

About the stabilizer diode, it did not work for me. I used a hair dryer at different positions and the result was dissapointing. But I read that many people had good results so I guess the diode they used were very leaky, more than mine. I'd have to try with other diodes...

The rockface has a smart way to keep things stable with varying temp, but the led at the collector may compress the signal a little...

mac

[gez]

If a leaky germanium transistor falls off a workbench when nobody is around...does it even make a sound??

Sorry, I'm in a silly mood tonight...

[Transmogrifox]

If a leaky germanium transistor falls off a workbench when nobody is around...does it even make a sound??

Sorry, I'm in a silly mood tonight...

I don't know, but you'll know it happened when you come back and notice it leaked on your floor 

[vanessa]

About the stabilizer diode, it did not work for me. I used a hair dryer at different positions and the result was dissapointing. But I read that many people had good results so I guess the diode they used were very leaky, more than mine. I'd have to try with other diodes...

The rockface has a smart way to keep things stable with varying temp, but the led at the collector may compress the signal a little...

mac

I'm not certain that that would be a great way to test the stab diode. Maybe on the box a little itself. I think it helps with moderate temp changes, after that it's time to go si!

[vanessa]

Guess what!

I was a leaky stab diode...

Mac got me thinking about that stab diode so I went on the Brit Face page, they talk about it should work great unless you have a leaky transistor (which I tested and found not to be the case) or a leaky diode. I pulled the diode and wham-o! Problem solved.

I got the diode from Futurlec, so I guess I got what I paid for... 

[nelson]

futurlec sell germanium diodes?

news to me

I got 3 futurlec orders in the last week. No real problems, it even included the 3PDT switches that were missed a few orders ago.

[vanessa]

Yes they sell 1N34A's. 10 for $.50.

I just built a Tone Bender with one as well and I have the same problem not quite as bad as the Fuzz Face mentioned above. I don't think I'm going to use those anymore.

[markphaser]

What does a leaky germanium transistor sound like?

Less fuzzy because the Emitter to Collector current is not going through the transistor its bypassing it or maybe creates low oscillations/squeals. The Base current doesn't get across to the collector maybe a potential difference?

Just taking a guess

[petemoore]

  At 'that' temperature...
  A FF isn't fully tested until at least finger heat is applied to Q2 [then sound and bias checked], Q1 seems more stable.
  I plugged in Ge devices straight in from the sub zero weather one night, hard input produced 'ghht' 'glarthxxx' 'glthh', because of no bias. no tonebending that night.

[MartyMart]

While we're on the "time of Si" trip ....

I just found a few SC238 Si transistors in a "Rat shack-type" grab bag and put them in
My "Gus Smalley FF", they are very small "thin" Si's with a flat back..... WOW
They sound fantastic !!  anyone aware of these little things ?  as I've never seen
them before.... !
They turned the FF into a RAT on steroids !

Here's a data sheet, but its SC2383 : http://pdf.alldatasheet.com/datasheet-pdf/view/53355/FAIRCHILD/KSC2383.html

MM

[markphaser]

ok and

[R.G.]

Nota bene:
Germanium transistors may be leaky for two quite different reasons. The junction may be inherently leaky because of poor diffusion, or it may be leaky because of surface contamination of the outside of the semiconductor pellet.

Contamination of the pellet makes for a lot of hiss, and you can hear that easily. Inherent junction leakage does not have any particular sound.

Leakage may make for a tone shift inside a circuit by shifting the bias to a point where the device is not linearly biased, as in the soft distortion of the Rangemaster, or it may make for gated farty sounds as a result of bias. But its a result of the bias shift in the circuit, not the "sound" of leakiness. So there may be a characteristic sound of a leaky transistor *in a given circuit * that you could recognize easily enough, but that same sound would not necessarily be the case in a different circuit.

[Rick]

I had this problem once, a very hissy circuit (sounded like heavy rainfall). I yanked out the first tranny and tested it with RG's tester. It was a very leaky one, well over 1000 microamps. Changed it and it worked perfectly. I test them all now before builds.   ...Rick