22 Aug
2008
22 Aug
'08
12:29 a.m.
Chuck Guzis wrote:
Just before transistors began to be used in auto radios, "space
charge" tubes made a brief appearance, running their plates and
heaters from the 12v battery. No vibrator supply. Some of the
earliest transistor designs used a transistor only in the audio
output stage, among them the Delco "Wonder Bar" models.
I remember working on, or dismantling, some of those as a little kid. Memorable
for the absence of hi-V supply, hybrid design, the big heat sink for the
transistor and the oddball case style of some of the transistors (some were
TO-3 but there was another "big-button" style that I don't know the
designation of).