reef-pi :: An opensource reef tank controller based on Raspberry Pi.

[BenB]

Should it be possible to connect 3 3W LEDs to each piece of this? Well, my project will have 9 3W blue LEDs, but connected in 3 series of 3 LEDs. Wouldn't it be interesting to have 1 piece of this for each section of 3 LEDs? I would like to control the total set of colors of the same LED with the same control. That's why I tried to control it with the MOSFET, because then I would connect all the LEDs of the same color to the MOSFET.

If you use 12V the input needs to be 3v higher that the output so 12 - 3 is 9V, each LED pulls about 3Volts so 9/3 is LEDs 3 max per driver. You can always connect the same PWM output to 3 drivers to control them together.

 

[ryangonzalezrz]

If you use 12V the input needs to be 3v higher that the output so 12 - 3 is 9V, each LED pulls about 3Volts so 9/3 is LEDs 3 max per driver. You can always connect the same PWM output to 3 drivers to control them together.

I see, it really makes sense. Before I buy that board you mentioned in China, I want to try to understand if it is possible to control it through the MOSFET, as Ranjib did. Can you tell me the best way to do it with the MOSFET?

 

[BenB]

I see, it really makes sense. Before I buy that board you mentioned in China, I want to try to understand if it is possible to control it through the MOSFET, as Ranjib did. Can you tell me the best way to do it with the MOSFET?

The quide is straight forward: https://learn.adafruit.com/reef-pi-lighting-controller/overview

However with the highpowerLEDs, you will need a driver that keeps the current stable at 700mA. The mosfet keeps the voltage stable not the current.

 

[ryangonzalezrz]

The quide is straight forward: https://learn.adafruit.com/reef-pi-lighting-controller/overview

However with the highpowerLEDs, you will need a driver that keeps the current stable at 700mA. The mosfet keeps the voltage stable not the current.

I see, so in addition to the MOSFETs, I need a driver for each set of colors, in this case 3 drivers if they can handle the full power? I thought that following the idea of the LED strip used in the guide, it would work, because it seems that the strip he uses does not have a driver.

 

[ryangonzalezrz]

The quide is straight forward: https://learn.adafruit.com/reef-pi-lighting-controller/overview

However with the highpowerLEDs, you will need a driver that keeps the current stable at 700mA. The mosfet keeps the voltage stable not the current.

I did a test with a 4.7k resistor that I had here and the LED lamps reached their maximum power, but they didn't turn off completely, what could it be?

 

[BenB]

I did a test with a 4.7k resistor that I had here and the LED lamps reached their maximum power, but they didn't turn off completely, what could it be?

It looks like the voltage of the did not drop low enough.

Another example of a driver on amazon:

 

[ryangonzalezrz]

It looks like the voltage of the did not drop low enough.

Another example of a driver on amazon:

Unfortunately the image you sent is not available and the link does not go to the driver, would it be possible for you to send it again? Another thing, could it have something to do with the frequency of the pca9685 board?

 

[BenB]

Unfortunately the image you sent is not available and the link does not go to the driver, would it be possible for you to send it again? Another thing, could it have something to do with the frequency of the pca9685 board?

On amazon please search for:

LD24AJTA 2 PCS Adjustable LED Driver Board 20W DC6~25V LED PWM Controller DC-DC Step-Down Constant Current Converter​

 

[ryangonzalezrz]

From what I understand, I will have to use each of these drivers for 3 LEDs anyway? But then, as an employee, would I use the PWM signal directly on this driver or the signal that comes from the MOSFET that I connect to this driver?
@BenB

 

[ryangonzalezrz]

On amazon please search for:

LD24AJTA 2 PCS Adjustable LED Driver Board 20W DC6~25V LED PWM Controller DC-DC Step-Down Constant Current Converter​

Hello, I found this one and it seems to be more powerful, do you think it works the same way as the one you sent me?



(MOSFET Trigger Switch Drive Module, PWM Regulador, Painel de Controle, 400W, 15A, Max 30A, 0-20KHz para Controle de Brilho da Lâmpada, DC 5V-36v


"https://a.aliexpress.com/_ms7i6iM")

 

[BenB]

Hello, I found this one and it seems to be more powerful, do you think it works the same way as the one you sent me?



(MOSFET Trigger Switch Drive Module, PWM Regulador, Painel de Controle, 400W, 15A, Max 30A, 0-20KHz para Controle de Brilho da Lâmpada, DC 5V-36v


"https://a.aliexpress.com/_ms7i6iM")

Please read the following to get a beter understanding of how high power leds work: https://www.ledsupply.com/blog/understanding-led-drivers/

 

[ryangonzalezrz]

Please read the following to get a beter understanding of how high power leds work: https://www.ledsupply.com/blog/understanding-led-drivers/

thank you my friend

 

[ryangonzalezrz]

So, I came to tell you what happened. My light control was not turning off completely and was not turning on the light at maximum power. The problem with the maximum power was the VCC of the PCA9685 board, which was connected to 3V3 and should have been connected to 5V, so it started turning on the light at maximum power. The problem with the light not turning off 100% was on the PCB board. Somehow, some rails were leaking power to other rails, and so it was always running even though the MOSFET was in low mode. I had to test the best rails to use and in the end it worked. Thanks for all your help @BenB

 

[bishoptf]

Does anyone know what changed in bookworm to hose the GPIO stuff up? Why oh why would they change that....when I have more time and it gets colder I will try to figure this out and see what we can do to update it...should work on the new OS...

 

[Simonv92]

Hi All! I'm currently doing some safety test on my Reef-Pi controller..
I've seen that if I disconnect the temperature sensor which controls the heater this one kicks in without any control.
How can I add a safety feature to disable the heater if the temperature reading goes below 2° - which means sensor disconnected of faulty?
Thank you!

P.S. I already tryed to create a second temperature controller but the second one disable the action of the first..