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I wanted to build a circuit where i would be able to control 90 LED's using one WS2811 and have a total of 60 WS2811.

In this circuit I hope to connect 30 LED's per channel, there is no need for me to control the individual LEDs thus there is no point in me going for the WS2812s which is commonly used.

I tried a few circuits that i saw online (sorry! dont have the links) and not of them worked, all i ended up was buring two of the IC's, and the circuit which did work I was unable to turn off the LED there was always a small amount of brightness.

Working voltage: 12V No. of LED's per channel: 30

This is how the LEDs are wired LED Wiring Diagram

I believe this is the circuit that i used Test Circuit

EDIT 1: I tried this circuit as well but the output is very low (brightness) enter image description here

EDIT 2:

I modified the above circuit to 100ohm at R1 and 10k ohm at R2, the transistor T1 is BC547 and T2 is BC817. After modifying the resistors and transistors, I am able to get a much higher brightness however, if I am to connect the negative directly to ground the Strip (the one i am testing with) consumes 1A current but via this circuit it is consuming only 600mA. Do i need to change T1 for better results?

Datasheet:

LED: https://www.dropbox.com/s/wz7xp7ghupoif5z/SMD5050-warm%20white%20specification.doc?dl=0

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  • \$\begingroup\$ This question as is doesn't give us much to work with. Please add schematics to the circuits you tried -- you can either attach an image of the circuit or draw it using CircuitLab (hit Ctrl-M while editing). \$\endgroup\$ – Null Oct 30 '14 at 18:50
  • \$\begingroup\$ You don't have enough voltage for anything near that. 30 LED in series will be like 75-90V dropped. \$\endgroup\$ – KyranF Oct 30 '14 at 18:56
  • \$\begingroup\$ There are so many potential ways for that to go wrong ... show us what you've done and tell us what worked & what didn't. \$\endgroup\$ – brhans Oct 30 '14 at 18:56
  • \$\begingroup\$ What is t1 Vce at 1 amp ? \$\endgroup\$ – Passerby Oct 31 '14 at 12:31
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There is an older version of the WS2811, that's the WS2801. This chip also has a constant voltage option, so you can control a FET with it that PWM's all your LEDs. Have a look at page 10 of the datasheeet!

Edit: You would need some LEDs in series (say 3) with a resistor, you can then connect 10 of these sets of "3 leds and a resistor" in parallel, to feed everything from 12 volts.

To switch high currents with the WS2811, you can connect e.g. a 10k resistor from 12V to the OUT pins and drive a MOSFET (e.g. TSM2314) with the pwm signal coming from the OUT pins.

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  • \$\begingroup\$ I did try it out, the problem is that the led strip doenst seem to completely turn off and I am also unable to get the max brightness \$\endgroup\$ – evolutionizer Oct 31 '14 at 5:24
  • \$\begingroup\$ As I understand well, you tried it with the WS2811. The reason this doesn't work is dat the pins are constant current driven. This means that the current trough your R2 will be constant. I advise you to use the WS2801 for this application. Another option is to connect 3LEDs (incl. a small resistor as explained on page 5 of the datasheet). When you connect the gate of a mosfet to the output pins (1,2 or 3) and use the mosfet to drive a group of 37 other LEDs, with a resistor limiting the LEDs to 18.5mA. The last one is however not the nicest solution. \$\endgroup\$ – Douwe66 Oct 31 '14 at 7:15
  • \$\begingroup\$ Can you explain why it is not the nicest solution? I had made a mistake in the code instead of going to 0 it stopped at one, sorry to have wasted all of your time one this. But now however my issue is that I am unable to draw more than 60mA, I have modified R1 to 100 ohm and R2 to 10k ohm. Transistor T2 is BC817 and T1 is BC547. \$\endgroup\$ – evolutionizer Oct 31 '14 at 11:06
  • \$\begingroup\$ It can probably work totally fine. It wouldn't be a nice solution if the driver was realy constant current. After reading the datasheet, because it is a still PWM driver it is as nice as the WS2801 in my opinion. I would however advise you use a MOSFET instead of a BJT, because they can switch higher faster and can be used for higher currents. When using a mosfet, you can easily switch more than 60mA. For example you can use the TSM2314, which can switch almost 5 amperes. \$\endgroup\$ – Douwe66 Oct 31 '14 at 16:59

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