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Jolly 7 · 11th Oct 2019, 12:25 am

I have an old 5mm red LED with a forward voltage drop of 2V. I need to use the LED to indicate the 37V DC feeding my LM317T regulator circuit. No more than 20 mA should be allowed to flow through the LED and I am using a one watt 2K resistor to achieve this (nearest to the calculated value of 1750 ohm I.e. 35/0.02).
I am using the LED with its series resistor connected in parallel to the input of the regulator. Can anyone please advise if there a better way ? The resistor's getting a bit warm in the current configuration, unless of course I bump up its wattage.

11th Oct 2019, 12:25 am	#1
Jolly 7 Octode Join Date: Feb 2018 Location: Southampton, Hampshire, UK. Posts: 1,063	LED indicator for A DIY PSU I have an old 5mm red LED with a forward voltage drop of 2V. I need to use the LED to indicate the 37V DC feeding my LM317T regulator circuit. No more than 20 mA should be allowed to flow through the LED and I am using a one watt 2K resistor to achieve this (nearest to the calculated value of 1750 ohm I.e. 35/0.02). I am using the LED with its series resistor connected in parallel to the input of the regulator. Can anyone please advise if there a better way ? The resistor's getting a bit warm in the current configuration, unless of course I bump up its wattage. Last edited by Jolly 7; 11th Oct 2019 at 12:26 am. Reason: clarity