Hello everyone,
I bought my Arduino Mega a year ago and never started doing something with it. As a child I drew close to electronics but I never went past the basic principles and rules. Now I want to combine two passions. Aquariums and electronics just to have simple tasks automated. Nothing fancy, yet.
I saw there are a lot of people using Arduino to automate water changes, lights, pumps and whatnot to their aquariums but there is little explanation on how to build the circuits. Started out with the wealth of information on the Arduino site and experimented with different circuits until I got the basics right. Now I want to venture further with my project which for the moment is targeting at controlling the lights above a 80 gallon (300L) reef aquarium. The fixture is made by me out of 36 3W LEDs and 5 10W LEDs.
I'm planning on adding more light so I bought a MeanWell switching power supply of 12V 16.7A for my project.
I designed the circuit so the LEDs are grouped in 4 channels all of them hooked to the PWM outputs from my Arduino. To control them I used a fairly popular and cheap power transistor (TIP122). The LEDs are glued to a large heatsink with thermal compound glue and also the transistors so that I can keep them cool.
The transistors are wired through a 1k resistor directly to the Arduino out pin and they are wired in the circuit on the -Vcc rail for each LED group.
The problem I think I'm facing now is circuit noise due to the PWM frequency. However, I tried putting decoupling capacitors with no success. The power supply emits a sharp noise that waves when the duty cycle is less than 75%. At full duty cycle everything seems to be working okay. The 10W LEDs tend to flicker a bit at about 10-15% duty cycle.
I have attached the schematic so far, bare in mind each LED represents an array of LEDs but for the sake of keeping things simple I've put just one for each channel.
The 3W LEDs are wired 3 in series and each "rail" is wired in parallel to the +Vcc and -Vcc. The 10W LEDs are all wired in parallel.
Any help on what I might be doing wrong and how I can do this correctly is greatly appreciated. Also, note I don't have an oscilloscope.
I bought my Arduino Mega a year ago and never started doing something with it. As a child I drew close to electronics but I never went past the basic principles and rules. Now I want to combine two passions. Aquariums and electronics just to have simple tasks automated. Nothing fancy, yet.
I saw there are a lot of people using Arduino to automate water changes, lights, pumps and whatnot to their aquariums but there is little explanation on how to build the circuits. Started out with the wealth of information on the Arduino site and experimented with different circuits until I got the basics right. Now I want to venture further with my project which for the moment is targeting at controlling the lights above a 80 gallon (300L) reef aquarium. The fixture is made by me out of 36 3W LEDs and 5 10W LEDs.
I'm planning on adding more light so I bought a MeanWell switching power supply of 12V 16.7A for my project.
I designed the circuit so the LEDs are grouped in 4 channels all of them hooked to the PWM outputs from my Arduino. To control them I used a fairly popular and cheap power transistor (TIP122). The LEDs are glued to a large heatsink with thermal compound glue and also the transistors so that I can keep them cool.
The transistors are wired through a 1k resistor directly to the Arduino out pin and they are wired in the circuit on the -Vcc rail for each LED group.
The problem I think I'm facing now is circuit noise due to the PWM frequency. However, I tried putting decoupling capacitors with no success. The power supply emits a sharp noise that waves when the duty cycle is less than 75%. At full duty cycle everything seems to be working okay. The 10W LEDs tend to flicker a bit at about 10-15% duty cycle.
I have attached the schematic so far, bare in mind each LED represents an array of LEDs but for the sake of keeping things simple I've put just one for each channel.
The 3W LEDs are wired 3 in series and each "rail" is wired in parallel to the +Vcc and -Vcc. The 10W LEDs are all wired in parallel.
Any help on what I might be doing wrong and how I can do this correctly is greatly appreciated. Also, note I don't have an oscilloscope.
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