Mr. Loflin, as usual I am so pleased to watch you explain so well circuits in general, including this updated one. Please keep on producing more videos as you are a wonderful teacher for so many practical electronic stuff for all hobbyist, and enthusiasts like me. Of course I have subscribed a long time ago now, and created special links of interests pointing at your videos.
About 25 years ago I assembled a circuit exactly similar to your first schematic. The output current varies by more than 10% depending on the temperature of the transistor. This phenomenon disrupts the performance of the device I built. The solution is to arrange the transistor as _'sziklai'_ for the LM317. I used 6.8 ohms as _Rbe_ (LM317 draws a current of around 100mA). The collector is connected to pin 2 and the input end of _Rsh._ Pin 1 is connected to the _Rsh_ output side as the final output. The constant current output will be 1.25/Rsh. The variation in output current is less than 1% due to the influence of transistor temperature, so the device I built can work well. Minimum drop out voltage was about 4V. Thank you
Great video. In regards to the PNP power transistor used, if I require a higher input voltage of say 200VDC and output current of 8 - 10 amps, could I swap out the single PNP power transistor for a Darlington Transistor? Also the LM317 would be changed to LR8NS
Newbie here. How can this be adjusted to be current limiting device. I want to test broken motherboards with voltage injection (usually 1 up to 5 volts) but need to protect the motherboard from too much current (100ma to 1000ma range). How would this be achieved ? Can you make video about this?
Pl make a video on foldedback current and its calculation of resistors ( linear regulated power supply with short circuit protection as fold back current limit). Thanks
