AD155

The AD155 is a low-frequency, medium-power germanium PNP transistor made in section 2200 (germanium devices) of IPRS Băneasa [1]. The licence for the section’s alloyed indium–germanium transistors – the SFT/EFT, AC and AD series and the ASZ18, AUY31 and AUY32 power transistors in TO3 cases – and for its EFD point-contact diodes belonged to the French firm SESCOSEM of Saint-Égrève, near Grenoble [1]. The section’s lines came from the Electronica works in 1962, and it stopped making germanium devices in 1982; having only the cover of IPRS’s germanium catalogue, the book reconstructs the list of the section’s products from prospectuses and publications up to 1989 [1].

The Agenda radioelectronistului (2nd edition, 1989) lists the AD155 among the bipolar transistors made by IPRS Băneasa, in the group of low-frequency, medium-power germanium PNP transistors, in a TO-66 package [2].

Coded as (Pro Electron system) [3]:

Part	Meaning
A	base material with an activation energy of 0.6–1 eV, e.g. germanium (0.67 eV)
D	low-frequency power transistor
155	serial number: three digits (100–999), for components for general use

Vce sat measured at IC = 1.5 A [2].