Hi i made a constant current driver with the LM338 for an 10w led. When i first turn it on and set it to 800mA it slowly begins to climb to 1A and more without stopping. At first i thought that my multimeter was playing games so i connected a needle panel ampmeter and it showed the same. This also happens with the lm317.
Another problem with the LM338 is that it does not keeps the current constant for some reason so with a small (3V 20mA) led it shows 18mA and when i connect a 1W led (3v 300mah normal) it shows about 14mah.
The lm317 stays at 18mA whatever load i connect to it.
Another problem with the LM338 is that it does not keeps the current constant for some reason so with a small (3V 20mA) led it shows 18mA and when i connect a 1W led (3v 300mah normal) it shows about 14mah.
The lm317 stays at 18mA whatever load i connect to it.
Last edited by a moderator: