How efficient would this circuit be???

trying to find out how efficient this circuit would be,

https://www.circuitstoday.com/wp-content/uploads/2009/05/led-ramping-circuit.jpg

so far it seems to be the best circuit i have seen to do the job at hand.

it will be powering a 2 amp load of leds (500 leds in total) so i may need to change the mosfet

The efficiency is simply the LED forward operating voltage divided by 6V (times 100 for per cent).

The switching circuit, as shown, as no significant effect on efficiency. For greater efficiency you need a switching type current-regulator with an inductor.

thats great for me then, this is the circuit i shall use. gonna go breadboard it now and see what i get

just 1 thing, if i use variable resistors for R1 and R2 will this allow me to vary the ramp in and out times??

R1 can stay the same. You would vary R2.

ahh ok, thanks for that

Hello there,


Another interesting thing about circuits like this is that if you place a transistor in series with a resistor and switch it at 50 percent duty cycle it makes the resistor look like it is twice as high in value, and that's about all it does. Different duty cycles make the resistor look like different value resistors, but it never increases the efficiency. To get better efficiency the circuit needs at least one energy storage element.