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Topic: PWM control of many LED's from arduino (Read 2524 times) previous topic - next topic

I like shiftPWM for when I need the rest of my arduino pins but you are likely to get the same results as softPWM if not worse.

dc42


I can't see in the first picture clearly due to the glare, but the pin below the "0" on the chip labeled "1360", the ZXLD1360, should be floating (soldered to a pad that goes nowhere) currently. Wire the bulb with +12V and GND, then connect to that pin through a resistor (~10K) and to a PWM output on the Arduino. Voila.


Good detective work, however the datasheet says that for PWM use, the ADJ pin should be driven from an open-collector or open-drain output.
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dtokez

Ah right so maybe instead of PWM'ing I would be better off trying to mod the IC's? What is a open collector or open drain output and how would I connect one?

dc42

To drive it from an open-collector output, use a small signal NPN transistor. Connect the emitter to ground, base to the Arduino PWM pin through a resistor (10K will do in this case), and collector to the ADJ pin of the IC. The IC and the Arduino need to have a common ground. You may need to bypass the bridge rectifier to achieve this.

Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

dtokez

Thanks DC I will think about trying that. What kind of signal transistor should I use? Although it will be bit of work and I would have to run 3 cables to each bulb instead of just two.

I'm now testing with a TLC which should have a fast PWM rate. If I can't notice the LED's flashing should I just stick with that or is it likely to damage the drivers in the bulbs?

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