why won't NPN germaniums work in my silicon fuzz face?

[ode2no1]

sorry, i know i just started another thread regarding my rat, but what can i say...i have a lot of projects going at once haha. anyway long story short, i had one germanium and one silicon fuzz face but one of the germanium transistors went out. the silicon version never did a whole lot for me and had some weird issues when turning the fuzz up to max so i decided that i'd give germanium one more shot, but i figured i might as well go with NPN. so...for some reason sticking npn germaniums in the sockets of my silicon fuzz face just doesn't work. i can't bias below about 7v with a battery that's already at about 8.6v. if i use a silicon transistor for q1 and germanium for q2 it isn't an issue. i can also bias two silicons no problem. what's the deal though? the circuit is identical to my pnp version except the polarity of everything is reversed. i've tried with 4 or 5 transistors and it's always the same thing. by the way i used the dragonfly smaller fuzz face layout.

[rustypinto]

Could be a couple of things:

- bias range might not accommodate the germanium.
- different pinout from silicon to germanium.
- dead transistor (test it if possible).

What kind of germanium transistors are they?

[petemoore]

  They should swap.
  er, What is the range of the Q2collector resistor value ?
 

[mac]

silicons bias with a lower resistor than germs, around 5k total.
i bet your germ at q1 is leaky and your trimmer is not high enough to send q2 colector to 4.5v.
the more leakage at q1 the higher the resistor needed at q2 to set 4.5v.
you should test your germs for gain and leakage.

mac

[ode2no1]

i used 2 different types of transistors, these random general electric npn's and then some russian gt404b's i just got, which do have a ECB pinout, but i twisted the pins to compensate. i tested the 404's for gain and leakage and tried two transistors that had under 300uA of leakage with gains of 86 and 101. i know sometimes you need a larger trimmer, so i guess i can give that a shot. blah...i really hate desoldering haha.

by the way...these gt404b's are crazy. they're literally the size of bullets. gonna be kind of a pain using them without modifying layouts, but if they sound good then that's fine by me. i found a couple of lots of 20 on ebay for $10 each plus shipping ($6) so i gave it a shot and ended up getting about 8 that had leakage below 300uA, about 8 between 300-400 and the rest were a little over 500, with one at about 900uA.

[mac]

look for toshiba transistors pnp 2sb56/54, 2sa49, etc. those have the right gain and leak around 50ua or less.
or matsushita pnp 2sb172/175/176 etc. these leak more, 100-200ua
also texas inst npn 2n388 or 2n1114 similar to toshibas but less reliable.
go japanese. period.

mac