Transistor AC128K PNP Germanium TO-1

Transistor AC128K PNP Germanium TO-1

Transistors
TRAC128K
Part.No: AC128K
€1.40
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The AC128K is a classic PNP Germanium Bipolar Junction Transistor (BJT) in a TO-1 metal-can package, fitted with the "K" mounting block/clip. Prized by DIY guitar pedal builders for authentic vintage fuzz tone (e.g. Fuzz Face) and by restorers of 1960s/70s audio equipment.

 

AC128K Germanium Transistor - The Classic Fuzz Face Sound

The AC128K is a PNP germanium alloy transistor housed in a TO-1 metal can with an added metal mounting block, historically used to improve heat sinking and mechanical stability in audio and switching circuits of the 1960s-70s. Today it is best known among guitarists and DIY pedal builders as one of the definitive transistors for recreating the original warm, dirty germanium fuzz tone in circuits such as the Fuzz Face.

Functions & Applications

  • Authentic Germanium Fuzz Tone: Delivers the warm, low-knee-voltage clipping character that silicon transistors cannot replicate.
  • "K" Mounting Block: Built-in metal clip improves heat dissipation and mechanical stability compared to bare AC128 units.
  • TO-1 Metal Can Package: Robust hermetic housing, ideal for hand-soldering on turret and eyelet boards used in vintage-style builds.
  • PNP Polarity for Vintage Circuits: Correct polarity for original positive-ground Fuzz Face and other classic 1960s/70s germanium designs.
  • Restoration Ready: Suitable for repairing period radios, tape recorders and audio amplifiers that originally used the AC128 family.

Technical Specifications

ParameterValue / Specification
Transistor TypeBJT (Bipolar Junction Transistor)
Polarity / ChannelPNP
Package / CaseTO-1
Collector-Base Voltage (Vcbo)32V
Collector-Emitter Voltage (Vceo)16V
Max Collector Current (Ic)1A
Power Dissipation (Pc)1W
DC Current Gain (hFE, min)45
Mounting TypeThrough-Hole (THT), metal block/clip

Frequently Asked Questions

Q: Is the AC128K suitable for a classic Fuzz Face build?
A: Yes, it is one of the most traditional PNP germanium transistors used in original Fuzz Face circuits, prized for its warm, unpredictable clipping character.

Q: What does the "K" in AC128K mean compared to a plain AC128?
A: The "K" denotes a version fitted with a metal mounting block/clip on the TO-1 can, originally intended to aid heat dissipation and mechanical fixing in equipment chassis; electrically it behaves the same as the standard AC128.

Notes

Legacy germanium part (1960s/70s design), typically sold as NOS or reproduction stock; gain (hFE) can vary between individual units as with all vintage germanium transistors.

Note: Price refers to one (1) piece. The component is shipped in bulk without individual packaging.

Transistor Type
BJT (Bipolar Junction Transistor)
Transistor Polarity / Channel
PNP
Transistor Case Style
TO-1
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