[HomeBrew] Germanium Transistors

[Steven Coles]

Dick,

 

The reason for using germanium transistors in low-frequency power converters is their low saturation voltage.  Germanium transistors drop ~0.2 V when saturated, Si ~0.4 V.  For the same current Ge transistor turn about half as much power into waste heat.  So until Si power transistors were greatly improved, Ge power transistors were the device of choice when squeezing every bit of efficiency and avoiding temperature rises.  After Si transistors improved their faster switching reduced power losses during switching times (when power losses and heating are greatest).  These days power MOSFETs beat BJTs (regardless of material) for low on resistance (and therefore, low on voltage drop).

 

73,

 

Steven, KD7YTE