Elvee, nice idea! When I read the posts I thought, could you use another '317 to do the de-noise duty instead of the extra NPN? After all, from the outside the 317 is just a transistor with 1.2V Vbe on steroids ;-)
Jan
Jan
Sure, it works, but not only can you adjust it, you need to, to suit the peculiarities of the target regulator: you cannot use the same setup for 50mA or 1A.Thanks Elvee.
The "Finesse" circuit works OK (and it can be adjusted)
You probably missed the title and the point of this thread: it is not about developing some kind of new revolutionary superreg, but about upgrading existing equipments using 317/337's, which certainly number in the millions, if not more.OMG. A LT3042 with an external transistor to carry the dissipation is
> 40 dB better than any LM317, right from the start.
Circuit is in the data sheet.
I love the idea, although it may be a bit circular: I need to think about it, for exactly three months + one week. It will then be perfectly ripe...Elvee, nice idea! When I read the posts I thought, could you use another '317 to do the de-noise duty instead of the extra NPN? After all, from the outside the 317 is just a transistor with 1.2V Vbe on steroids ;-)
No, certainly not: I have tested it with various types, including a BC547 (don't remember the selection letter), and all worked, but the 337 gave a marginally lower noiseDoes it need only BC337?
I would look for dry solders or similar problems. The circuit in itself is very simple and straightforward, and if all the E-caps are OK and correctly connected, it should deliver the goodsI made this circuit with BC547C and LM338 - and don't have good result. It works as usual, without extra PSRR.
3V is OK: it should be around 1/4 of the output voltage, but as long as the transistor remains in it linear domain, it ought to work.I tried different R4, R5, R6 and different C2, C3, C4 (it is stable with C4 1 nF).
What voltage have to be on the Q1 collector? (I have about 3V). Thank you.
The figure could be improved by using a really high performance, low noise transistor