AC124s...

[mordechai]

Does anyone know anything about these transistors?  Never heard of them before but I'm curious to give 'em a try.

[brett]

Google?

[petemoore]

  GEO
  Technology of the Fuzzface.
  Explains the circuit, transistors, how to measure to choose them.
  It boils down to leakage and gain, some impurities.
  Slight differences once the makes or breaks the circuit difference is determined:
  LEakage and gain.
  Lotsa leakin' ones that...didn't quite make it because there were non leaky ones.
  The non-leaky ones that got tried and liked are either for sale, being tried, or misunderstood [imo].
  If you want to sort through others seconds, or know someone with secret stash it's one thing.
  The other thing is Smallbear measured/documented transistors.
  Then a blue moon transistor may appear inside a 50's or 60's transistor radio, or recording or other electronic device.
  I tried some 'AC' transistors, 128's, rough...extensive suscitations found them to be useless to me except as diodes [base emitter diode] was about it, rather just have bought the two pronged, smaller diodes and be done with junk Ge before beginning.