Tungsram 128k/176k transistors

[FLchuckles]

anybody know about these?  All i know is they are bi-polar.

i tried these in a fuzz face circuit- PNP- and no signal passed whatsoever. so i reversed each one in the circuit. (reversed the emitter and collector connections from the schematic)

signal passed...but it was very weak. low volume and little "fuzz".

are they just "low" gain..or am i doin something wrong? (i suspect the latter!! hahaha)

Thanks for any insight!

[chromesphere]

AC128K?   The K is the suffix for heatsink option.  Did you buy these in matched pairs from minifux on ebay?  I bought some ages ago.  unfortunately all of the ac176's were rubbish.  Thermal runaway.  Bin worthy.  Some of the ac128's were ok.  If your using them in a fuzz pedal you really need to measure them first.

[tonyharker]

AC128k are PNP but AC176K are NPN so Im not surprised they didnt work in a fuzz face.  Both transistors need to be the same type.
They are both Germanium transistors

[zombiwoof]

I have one AC128-01 (I think that's the designation) that also has the heat sink in a Fuzz Face (works great).  What is the difference between that and the AC128K, they look exactly the same?.

Al

[darron]

I've got bags of 100's of Tungsram's! especially ac128s



Not the best at all... Lots of noise. Gains and leakages are typical of older (even though they are not) cheaper devices. leakage can on average easily be 0.3mA +


i'm keeping mine to perhaps use as diodes one day

[chromesphere]

I use ac125's all the time.  Leakages vary depending on gain.  Low gain low leakage.  They sound good, 'all round'.  Can be noisy with lots of leakage, depends on the circuit too of course. That's my 2 cents.

[zombiwoof]

The ones the OP is talking about are not the regular AC128's, they are the ones that have the rectangular heat sink body with the hole in the middle of it.  As I said, I have one in one of my Fuzz Faces (an older modded red full size Dunlop), along with a 2SB176 in the other position, and it sounds good, much better than the stock out-of-bias transistors that Dunlop put in it originally.  I also changed out the output cap to the correct .01uf, instead of the .1uf that Dunlop almost always uses in their regular Fuzz Faces, which cut the muddy bass back quite a bit.  Also put a bias trimmer in place of the 8.2k resistor to dial in the bias.  So now it sounds like a proper Fuzz Face, not the overly bassy, crappy sounding pedal that it was stock.

Al

I've got bags of 100's of Tungsram's! especially ac128s



Not the best at all... Lots of noise. Gains and leakages are typical of older (even though they are not) cheaper devices. leakage can on average easily be 0.3mA +


i'm keeping mine to perhaps use as diodes one day

[darron]

better take a photo





the one at the top is a tungsram branded modern one: