1954 Regency TR-1
Shirt pocket radio, thermoplastic cabinet
5 x 3 x 1 1/4 inches / 127 x 76 x 31.8 mm
Four transistors (Texas Instruments, TI210, 2x TI222, TI223; + one diode (various manufacturers), superheterodyne circuit
22.5 volt battery
Manufactured by Regency Division, Industrial Development Engineering Associates (I.D.E.A.), Indianapolis, Indiana
The world's first commercially-produced transistor radio — released in October, 1954
Three versions of the TR-1 are shown here:
1) One of the earlier TR-1s (ivory cabinet here) with a very low serial number just over 14,000 — this has the hollowed-out "dimple" depression on the inside back cabinet face made necessary to accommodate the set screw head found on the first version of the tuning capacitor used in the TR-1, and because of this a small label was used that would not interfere with the dimple. And as you can see from the chassis photo below, the tuning cap problem had been resolved by the time this unit was assembled, even though the tuning cap itself has a very early date code of 445 (week 45 of 1954: the first week of November '54). The transistors here are unmarked other than for the TI logo on one face of each transistor and painting on top of each transistor (dark green, yellow with a blue dot, 2x brown with a white dot). The diode in this unit is a typical bright red Raytheon epoxy diode with a partial designation of "K 513", which seems pretty obviously to have been, "CK513", though I haven't been able to find any such number as belonging to a Raytheon diode — all sources I've found give "CK513" as just an undescribed semiconductor from an undesignated manufacturer.
2) A later version (green cabinet here), free of the dimple problem and allowing for a larger label on the inside back cabinet face. Here, the tuning cap has a date code of 506 (week 6 of 1955, the second week of February '55). Note that the serial number on this example is already over 60,000. The transistors in this unit are marked both by numbers on one face and color-coded paint on top (dark green: 517; yellow with dark blue dot: unreadable; red with dark blue dot: unreadable; black with red dot: 516). The diode here is a small silver can marked "DR117".
3) A Bulova 250 version made by Regency. The tuning cap has a date code of 536 (week 36 of 1955, early September '55). All four transistors here are marked with the TI logo on one face and the number 535 on the other face, plus the mysterious painted color-coding on top of each transistor. The diode here is a silver can marked simply as "DR".