Go Down

Topic: PWM control of many LED's from arduino (Read 2629 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.
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

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?

Go Up
 


Please enter a valid email to subscribe

Confirm your email address

We need to confirm your email address.
To complete the subscription, please click the link in the email we just sent you.

Thank you for subscribing!

Arduino
via Egeo 16
Torino, 10131
Italy