I learned something reading your thread too, Tony. I've been a circuit designer for a very long time, but had never seen the transistor circuit at the input to the LM317 used quite that way.
Since I was curious, I did a bit of research and found the reason and design rationale for using that circuit - to protect the LM317 in the case of a short-circuit at the output.
Makes perfect sense, and now I know something new too!
What it's all about - learning. It's what makes this fun!
Since I was curious, I did a bit of research and found the reason and design rationale for using that circuit - to protect the LM317 in the case of a short-circuit at the output.
Makes perfect sense, and now I know something new too!
What it's all about - learning. It's what makes this fun!
Just to clarify... (the bane of engineers...) My experience has been in RF and Analog circuit design, but not much in tubes for the past 25 or so years.
Tubes are a new-old area for me. I grew up fixing tube radios and TeeVees for friends and neighbors, but I've been working with ICs for many years. Silicon is neat - for instance, I've designed a 3-channel receiver card for a passenger-airliner IFE application using an Xceive chip, which is a little 10mm-square piece of sand that can receive TeeVee @RF in any format worldwide and produce color-video and stereo-audio. It's a stunning piece of technology, but lacks the "magic" of the tube designs.
Of course, the up-side (of the silicon design) is that an equivalent tube design would be the size of a desk and require a forklift to move, whereas the little card I did was about 3" x 4" and needed only about 4Watts of DC power.
It's all good, though! Tubes have a special magic, it's why we play with them (or, in my case, dream for years and THEN start to play with them!)
Have fun!
Tubes are a new-old area for me. I grew up fixing tube radios and TeeVees for friends and neighbors, but I've been working with ICs for many years. Silicon is neat - for instance, I've designed a 3-channel receiver card for a passenger-airliner IFE application using an Xceive chip, which is a little 10mm-square piece of sand that can receive TeeVee @RF in any format worldwide and produce color-video and stereo-audio. It's a stunning piece of technology, but lacks the "magic" of the tube designs.
Of course, the up-side (of the silicon design) is that an equivalent tube design would be the size of a desk and require a forklift to move, whereas the little card I did was about 3" x 4" and needed only about 4Watts of DC power.
It's all good, though! Tubes have a special magic, it's why we play with them (or, in my case, dream for years and THEN start to play with them!)
Have fun!
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