Transistor AC127K NPN Germanium, 0.5A TO-1

Transistor AC127K NPN Germanium, 0.5A TO-1

Transistors

Reference: TRAC127K

Part.No: AC127K

€1.40

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The AC127K is a germanium NPN transistor in a TO-1 heatsink-block package, designed for audio amplifier stages and vintage electronics repair where extra thermal stability is needed.

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Description
Product Details

AC127K Germanium Transistor - Heatsink-Block Version for Audio Power Stages

The AC127K is the heatsink-block variant of the classic AC127 germanium NPN transistor, built for applications where the extra low Vce(sat) and warm sound of germanium are wanted alongside better heat dissipation than the plain TO-1 version. It remains a popular choice for restoring vintage transistor radios and portable audio amplifiers from the 1960s-70s, as well as for boutique fuzz and overdrive pedal builders chasing an authentic germanium tone.

Functions & Applications

Germanium Construction: Delivers the characteristic warm, low-headroom clipping sought after in vintage fuzz and audio circuits.
Heatsink-Block (TO-1) Package: The bolted metal block improves heat dissipation versus the standard AC127, reducing the risk of thermal runaway typical of germanium devices.
Low Vce(sat) at Low Voltage: Well suited to battery-powered vintage designs running on 6-12V rails.
Direct Legacy Replacement: Drop-in replacement for the original AC127K used in period radios and amplifiers.

Technical Specifications

Parameter	Value / Specification
Transistor Type	BJT (Bipolar Junction Transistor)
Polarity / Channel	NPN
Package / Case	TO-1
Collector-Base Voltage (Vcb)	32V
Collector-Emitter Voltage (Vce)	12V
Max Collector Current (Ic)	0.5A
Power Dissipation (Pc)	0.34W
DC Current Gain (hFE)	~50

Frequently Asked Questions

Q: What does the 'K' suffix mean on the AC127K?
A: It denotes the version fitted with a square metal heatsink block, used to bolt the transistor to a chassis or larger heatsink for better thermal stability than the plain AC127.

Q: What is the complementary PNP transistor for the AC127K?
A: The germanium complement is the AC128 (or its heatsink-block equivalent, AC128K), commonly paired with the AC127K in push-pull audio output stages.

Notes

This is a legacy/vintage germanium transistor, mainly stocked for repair of period audio equipment and boutique fuzz pedal builds. The heatsink block should be securely bolted to a chassis or heatsink in higher-dissipation designs to avoid thermal runaway, a known characteristic of germanium devices.

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: NPN
Transistor Case Style: TO-1

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