Dwight V. Jones – Continued




As the GE Semiconductor Applications Engineer specializing in audio/HiFi circuits, Dwight Jones worked with rapidly evolving technology in the 1950s and 1960s.  In the photo above, the 2N167 on the left is one of the earliest transistors to be used in an audio circuit by Dwight.  This device is a crudely constructed grown junction germanium transistor from the mid 1950s and is shown in the earliest GE Transistor Manuals in both radio and audio applications.  On the far right is a prototype of a silicon monolithic diffused IC device developed by GE in the late 1960s. Dwight developed Application Notes on this line of consumer audio devices, which were marketed as the PA (Power Amplifier) series.  The PA 237, for example, was a Two Watt audio amplifier containing seven transistors; it was intended to be used in consumer products such as TVs and radios.   The 2N508 (second from left) was used extensively by Dwight in his early transistor HiFi designs.  This device was introduced by GE in the late 1950s and is a germanium alloy junction transistor.  According to Dwight “The 2N508 was one of my favorite early transistors. It had relatively high gain and low noise.  I used it a lot for audio projects”.   The three unmarked devices in the center of the photo are all GE prototype silicon transistors from the 1960s which Dwight evaluated for HiFi usage.  The silver can-style unit was marketed as type 2N2107 – it is a silicon diffused unit designed as a medium power audio output transistor.  The remaining two units in the photo (both with heatsinks) are prototypes of the D40 series of late 1960s silicon NPN audio power transistors.  The 15 year timeframe from the mid 1950s to the late 1960s shown in the photo above illustrates the dramatic changes in audio semiconductor technology that occurred during Dwight’s  career. 




In the July 1959 edition of Electronics World magazine, Dwight Jones published an article on an all solid-state stereo tape amplifier.   This was pioneering work and represents some of the earliest published material for true HiFi caliber transistorized magnetic tape amplifiers.  Dwight developed several versions of this circuitry, which appeared in various 1950s and 1960s publications, including Electronics World, Journal of the Society of Audio Engineering, and editions Four through Seven of the GE Transistor Manual.  The circuit board shown above is a commercialized example of these important applications developed by Dwight – this board is the circuitry for one channel of a stereo tape amplifier.  There are four 2N508 germanium transistors in the preamp section (one silver and three black units shown on the right).  The power output is provided by silicon diffused silicon 2N2107 style units (one is shown with finned heatsink in the upper left of the board).




Go To Jones Oral History, Page 5

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