IGaging DRO power supply questions

[martik777]

Because according to ohms law I=V/R.

At 3.3v those two resistors will be drawing 66mA.

Not a lot but also not insignificant. To put it on perspective your 36ohm resistor is drawing 0.157W of power. That's half the rating of a 1/4W resistor and over current for a 1/8W resistor. Both will feel pretty warm with the 1/8w probably burning out.

At the end of the day it is just inefficient. You could achieve the same with a 36k 22k resistor combination and drain 1/1000 of the power draw.

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I measured current going to the DRO at 44µa. The resistors are fairly warm, maybe 35C. Not 00% sure I did it right but I broke the + wire going to the DRO and connected the leads of the meter in between and set the dial to µa
I also, noticed that some LM317 calculator recommend R1 not exceed 1k and indeed, if I use over 10k the Vout is way too high