HIGH Leakage Germs... What to do??

[Govmnt_Lacky]

I have a few REALLY cool looking 2N671 germ transistors that I just cannot bring myself to put on the "crap" list.

They are deserving of the "crap" list because they have IMMENSE leakage!  On the RG-meter from Geo, when I apply power with a 9V, they settle at around 3.0V 

I know this is typically unacceptable by a long way however, they just look Awesome and I really want to use them for SOMETHING!!!

I know this is a re-hash of many older threads however, What should an OCD inflicted packrat do with these??

[haveyouseenhim]

Could they be used as diodes maybe?

[midwayfair]

Breadboard a tonebender, put them in Q3. If they don't work there, then use them as diodes.

[LucifersTrip]

FZ-1A or variant

[Jazznoise]

Doesn't the Harmonic Percolator need a leaky Ge transistor?

Also, a touch off topic - but how does leakage skew a HFE reading? Will a leaky transistor show a noticably lower hfe or higher?

[therecordingart]

Buffer?

[electrosonic]

I think the buffer is good idea..

http://www.muzique.com/tech/ge_buff.htm

Andrew.

[mac]

You can use this bias,

Rb1 = 100k (Vcc to base)
Rb2 = 33k - 39k (base to gnd)
Rc = Re = 10k
Bypass emiter with a cap
Vc will be at about 6.5v and 5.5v depending on leakage and Rb2

Rb1 = 100k (Vcc to base)
Rb2 = 22k - 27k (base to gnd)
Rc = 10k
Re = 5k
Bypass emiter with a cap
Vc will be at about 5.5v and 4.5v depending on leakage and Rb2

These are quite temperature stable bias. You can use 3 stages like a BMP.
Just an idea.

mac

[darron]

I think the buffer is good idea..

http://www.muzique.com/tech/ge_buff.htm

Andrew.

I tried building the ge buffer because I always have piles of he's to recover. Unfortunately, noise levels seem to be almost proportionate with leakage. Tried a few transistors and just couldn't bring myself to accept the noise for an effect that has no 'effect' over a FET.


Just put them in random gaps on your PCBs in the future maybe!

[pinkjimiphoton]

you can reverse bias an 1n34 or something between emitter and base, too, in some fuzzes...the leakage from the diode helps compensate for the leakage from the transistor. or something.

sometimes really leaky ge's sound awesome. they can be good sometimes in a fuzz face, but in harmonic perc, they really seem to shine.

[haveyouseenhim]

Just put them in random gaps on your PCBs in the future maybe!

Haaa   good one

[midwayfair]

you can reverse bias an 1n34 or something between emitter and base, too, in some fuzzes...the leakage from the diode helps compensate for the leakage from the transistor. or something.

No, that just compensates for increased leakage with increased temperature. The Fv of the diode rises with the temperature, offsetting the leakage increase.

[LucifersTrip]

Also, a touch off topic - but how does leakage skew a HFE reading? Will a leaky transistor show a noticably lower hfe or higher?

"With germanium's inherently higher leakage, this just makes a leaky device look like a higher gain device."

http://www.geofex.com/Article_Folders/ffselect.htm

[Electron Tornado]

I just put a leaky germanium in a Rangemaster clone. It wasn't supposed to work that well, but man did it have some amazingly good tone!

[darron]

I build a lot of rangemaster style circuits with pnp germaniums. No volume/tone problems with leaky transistors at all as long as you bias them correctly. Is there any noise trade off though?

[Electron Tornado]

I build a lot of rangemaster style circuits with pnp germaniums. No volume/tone problems with leaky transistors at all as long as you bias them correctly. Is there any noise trade off though?

This one is still on the breadboard, under a flourescent light, and I don't have noise problems. I'm using NPN transistors biased at +7V.

[darron]

I build a lot of rangemaster style circuits with pnp germaniums. No volume/tone problems with leaky transistors at all as long as you bias them correctly. Is there any noise trade off though?

This one is still on the breadboard, under a flourescent light, and I don't have noise problems. I'm using NPN transistors biased at +7V.

Sweet. Need to play with more npn's, they seem a lot better.

Fluorescent shouldn't be a problem. I mean the ge hiss more than mains hum. Like a hissy background crackle they make.

Thanks.

[chromesphere]

I would try them in a circuit before ditching them.  I know alot of people say 'over 300-500ua leakage and they are useless'.  I personally havent found that.  

Some circuits seem more forgiving then others.  From memory, it may have been a soul bender and a buzz around that didnt seem to care to much about hfe. (q3 was around 2000ua of leakage i recall).

Yeah, anyway..i'd give them a go!

Edit: wouldnt bother with the AMZ ge buffer.  It's got a few issues that you have to address (i found stock, it actually sucked treble and had to change some values to correct it).  You end up just asking yourself "why didnt i just build an IC or silicon buffer.

Paul

[kaycee]

You might want to try Mictester's op-amp Buzzaround.

It actually requires a leaky germ for the clipping stage, how leaky? You could find out

IvIark has a vero for the NPN version: http://tagboardeffects.blogspot.co.uk/search?updated-max=2012-12-10T05:44:00Z&max-results=10

You can flip a PNP to work in the negative ground circuit as shown above with only a little tweaking. Schematic at the top of page two.

http://www.freestompboxes.org/viewtopic.php?f=13&t=9401&hilit=buzzaround&start=20

One of my favourite fuzzers.