BobCajun
Well-Known Member
I made a cool LED PWM dimmer from an Arduino Nano microcontroller. It was cheap and relatively easy. A bit of screwing around connecting everything up but nothing too bad.
So I got some Nano clones (DCCduino), transistor output optocouplers and 250 ohm resistors. I found this idea from the second post on this page. The optocouplers were about 80 cents each. The resistors were a dollar something each because I got 5w ones to be on the safe side. I guess I didn't need that high a wattage but for a dollar something who cares? So I got 10 of each. The couplers and resistors cost me about $50 with UPS shipping, which was $25. Figured I might as well get 10 to make it worth the shipping. I have 5 Nanos and can get another 5 locally if I need them.
So I slapped it together and it worked perfectly. I set it for 400 microseconds on and 800 off, a 33% duty cycle. I've read a patent that claims that such a pulse setting would increase yield by about 50% while using about 1/3 the power. Here's the patent, you can look at the graphs to see what I mean. Will it actually work? Guess I'll soon find out. Could be total BS or only work with certain plants or very low light levels. It sounds too good to be true but it was worth me checking out. It certainly looks a lot dimmer. Will the growth be slow because of that or will it in fact be boosted by 50%? If I notice slow growth or yellowing I'll put it back to normal. With that much dimming, it would be like about 150w per sq meter, so obviously if the patent is wrong the plants will barely grow.
At least I have dimmers I can set up any way I want. I can program in gradual change of brightness to mimic sunrise and sunset, or change the spectrum at certain times, if I used mixed monos. Having a programmable microcontroller on your dimmer leads is a vast step up from a potentiometer. They cost me like $13 each to make, which is actually pretty much the same as you can buy a simple rotary potentiometer for. I can do lots of stuff with Arduinos. I can do only one simple thing with a potentiometer.
BTW, you really do need to reverse the PWM programming like the linked post says. I checked it to make sure by making the off time in the code, which would really be on time after going through the coupler, only 100 micros and it was dimmer than when I had it at 400. Here's the code as it is shown in the Arduino site. You just change the 100 and 900 to whatever you want. Since it needs to be reversed, I used 800 and 400.
void setup()
{
pinMode(13, OUTPUT);
}
void loop()
{
digitalWrite(13, HIGH);
delayMicroseconds(100); // Approximately 10% duty cycle @ 1KHz
digitalWrite(13, LOW);
delayMicroseconds(900);
}
So I got some Nano clones (DCCduino), transistor output optocouplers and 250 ohm resistors. I found this idea from the second post on this page. The optocouplers were about 80 cents each. The resistors were a dollar something each because I got 5w ones to be on the safe side. I guess I didn't need that high a wattage but for a dollar something who cares? So I got 10 of each. The couplers and resistors cost me about $50 with UPS shipping, which was $25. Figured I might as well get 10 to make it worth the shipping. I have 5 Nanos and can get another 5 locally if I need them.
So I slapped it together and it worked perfectly. I set it for 400 microseconds on and 800 off, a 33% duty cycle. I've read a patent that claims that such a pulse setting would increase yield by about 50% while using about 1/3 the power. Here's the patent, you can look at the graphs to see what I mean. Will it actually work? Guess I'll soon find out. Could be total BS or only work with certain plants or very low light levels. It sounds too good to be true but it was worth me checking out. It certainly looks a lot dimmer. Will the growth be slow because of that or will it in fact be boosted by 50%? If I notice slow growth or yellowing I'll put it back to normal. With that much dimming, it would be like about 150w per sq meter, so obviously if the patent is wrong the plants will barely grow.
At least I have dimmers I can set up any way I want. I can program in gradual change of brightness to mimic sunrise and sunset, or change the spectrum at certain times, if I used mixed monos. Having a programmable microcontroller on your dimmer leads is a vast step up from a potentiometer. They cost me like $13 each to make, which is actually pretty much the same as you can buy a simple rotary potentiometer for. I can do lots of stuff with Arduinos. I can do only one simple thing with a potentiometer.
BTW, you really do need to reverse the PWM programming like the linked post says. I checked it to make sure by making the off time in the code, which would really be on time after going through the coupler, only 100 micros and it was dimmer than when I had it at 400. Here's the code as it is shown in the Arduino site. You just change the 100 and 900 to whatever you want. Since it needs to be reversed, I used 800 and 400.
void setup()
{
pinMode(13, OUTPUT);
}
void loop()
{
digitalWrite(13, HIGH);
delayMicroseconds(100); // Approximately 10% duty cycle @ 1KHz
digitalWrite(13, LOW);
delayMicroseconds(900);
}
Last edited:
do you have an external power source for the arduino?
