07-16-2018, 09:16 PM
So I did some research and did some testing.. here are the results:
When driving the LED lights at full power the transistors do not heat up beyond lukewarm - in other words, I can easily place my hand (or finger) against them and not feel uncomfortable, so I am ruling out the over-current idea (for now)
What I have found in research is that most wiring diagrams and recommendations for the TIP122 and Arduino environments is to put a resistor in between the collector on the transistor and the control side (arduino/PCA9685 board). This is most commonly found when driving a motor off of the 5V controller, however it is also recommended for driving any load as a shield to the controller.
My next step is to get a few 1kOhm resistors and wire them in and test it out.
As a safe measure I will also be adding my heat syncs to the transistors to ensure proper heat dissipation. As a side note, I also have the box that the transistors and board are in located directly in the path of my HVAC vent, and this time of year in NJ we are seeing regular 90 degree weather, so my central air runs throughout the day when the daylight LEDs are on - I consider this a lazy form of passive cooling.
My next post will include pictures and results as described here. If I can get this working reliably at full power then this is definitely something that I think others could use, and something I will continue to use moving forward - especially when I upgrade to a larger tank considering that I am only using 4 channels of the LED controller, and I would assume with matched transistors/lights I should be able to run certain channels in parallel on a much larger setup (testing to come later, after I win the lottery LOL)
When driving the LED lights at full power the transistors do not heat up beyond lukewarm - in other words, I can easily place my hand (or finger) against them and not feel uncomfortable, so I am ruling out the over-current idea (for now)
What I have found in research is that most wiring diagrams and recommendations for the TIP122 and Arduino environments is to put a resistor in between the collector on the transistor and the control side (arduino/PCA9685 board). This is most commonly found when driving a motor off of the 5V controller, however it is also recommended for driving any load as a shield to the controller.
My next step is to get a few 1kOhm resistors and wire them in and test it out.
As a safe measure I will also be adding my heat syncs to the transistors to ensure proper heat dissipation. As a side note, I also have the box that the transistors and board are in located directly in the path of my HVAC vent, and this time of year in NJ we are seeing regular 90 degree weather, so my central air runs throughout the day when the daylight LEDs are on - I consider this a lazy form of passive cooling.
My next post will include pictures and results as described here. If I can get this working reliably at full power then this is definitely something that I think others could use, and something I will continue to use moving forward - especially when I upgrade to a larger tank considering that I am only using 4 channels of the LED controller, and I would assume with matched transistors/lights I should be able to run certain channels in parallel on a much larger setup (testing to come later, after I win the lottery LOL)
