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Topic: dimming leds with tip122 and voltage variable (Read 874 times) previous topic - next topic

murdocx

Im trying to dimming two LEDs in parallel with a power supply of 3-48V variable and 1.4A constants with a TIP122. If I use a 3.7V battery I have no problems, but the supply give me 48V and tip begins heating extremely, but leds only needs 3V. This is like transistor demands all power capacity. Im using a 2k2 resistor on the base.
any idea? thanks

Runaway Pancake

Schematic?

[Draw it out on a sheet of paper, take a picture of that and include it as an attachment.]
"Hello, I must be going..."
"You gotta fight -- for your right -- to party!"
Don't react - Read.
"Who is like unto the beast? who is able to make war with him?"

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