Current mirror for LEDs

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01:45:38

Fuente de corriente para alimentar leds utilizando espejos de corriente. La corriente constante que circulará por los Leds se ajusta mediante un potenciómetro. 

published 11 years ago

INTENDRO

11 years ago

I recently tried such a circuit on a pcb. The mirror has a big error if the transistors are not exactly the same. It's not even enough if they are the same type. They really have to be from the same silicon waver in order to have the same characteristics. To avoid this problem: Add a resistor between each emitter and ground. I recommend 1V from the base of the transistors to ground. -> 0.3V across each of these resistors. Use U=R*I to calculate the resistor with I being the mirrored current.

hurz

11 years ago

@INTENDRO yes right transistors have to match or at least calibrated. And even more, keep in mind the different temperatur because of different power dissipation. @asierdanjou check also this http://everycircuit.com/circuit/5696776581414912 keep it up!

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