which LED fader...?

hi all

i've been asked by someone to provide interactive pulsing LEDs for a project they are working on. it seemed simple enough - 3 sets of 8 or 9 LEDs that pulse at a certain rythm and when triggered by a proximity sensor (probably the sharp GP2D12) pulse at a faster rate for a while.

however, since looking into it and making a few test circuits i'm getting a bit lost as to which is the best approach. i've made nice pulsing circuits with LM324 op-amps and variable resistors and i've also got nice pulsing just using the PWM from the arduino. each of these has its limitations though - i didn't find a way to plug the arduino into the op-amp based circuit and i can't run enough LEDs from the arduino PWM pins. so i began looking at either an LED driver such as the TLC5940 or using an SPI digital pot - i'm pretty sure that one of these two will be the correct solution but instead of guessing which one (time and money prevents me trying both) maybe someone can recommend or point me in the right direction.

thanks

so i began looking at either an LED driver such as the TLC5940 or using an SPI digital pot

Forget the digital pot, it won’t take the current. Go with the TLC5940.

i didn’t find a way to plug the arduino into the op-amp based circuit

You have to push really hard once you have aligned it carefully.

Grumpy_Mike:
You have to push really hard once you have aligned it carefully.

haha... i see what you did there. thanks.