I'm a digital guy so it's a bit of a dredge to get through the analog aspects of electronics. I can do it but I need a few clues and a little reassurance that I'm going in the right direction(s.)
I have an inductive device with a 9V limit. I have 5V and 12V available.
I'm looking at a really nice thread about controlling LM317 with PWM at http://forum.arduino.cc/index.php/topic,201154.0.html I had already seen the EDN page that that thread references. For example the R/C to smooth the PWM, I'm OK with that.
I understand that the low end of the voltage range of the 317 can be brought to 0V by using a -V on the 358. I understand how to use LM337 to do that. That's cool.
I understand that with a 12V input the LM317 has an 'unavailable' voltage drop, but I don't know what the name of the spec is in the data sheet. Regardless, if it's in the 1.5-2V that brings me closer to the target of 9V.
( I know I could limit the PWM but that costs resolution.)
I understand that using the correct -V on the 358 will bring the output down to 0V. That part I can figure out.
Rather than just asking for 'an answer,' the best I'd like to see is a web page that describes clearly and most importantly simply how to adjust the gain on the 358. The only pages I've found assume the reader has a lot more background than I have.