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

bishoptf · Jan 4, 2019

Bigtrout said:
Can u post your circuit, if you dont drive a fet correctly and it works in the linear region(not fully on or off) they can get pretty hot. Are you trying to drive a large fet directly from a pwm pin?

Since you are new to electronics, may I make a suggestion?

Get a premade mosfet power module that can be driven from 3.3 or 5.5 logic level.
Post back with your specifics and I can make a suggestion. You need to know whether you are switching your light on the positive side or the negative side. I have to drive my light on the high side and a opto isolated p channel mosfet board is only 4 dollars and will do 1khz pwm frequency and can hook right to the pwm pin of the rpi or the pca.

I am using this diagram - https://learn.adafruit.com/assets/2693 which is from this guide - https://learn.adafruit.com/rgb-led-strips?view=all#wiring
The article talks about using a TO-220 fet and lists this one - IRLB8721, my local electronics place did not have that particular fet but he had this one which should be as good IRLZ44N, another TO-220 low level logic fet. Right now I have no load I just have my meter connected to the output and I see constant voltage, it's no cycling at all and when I set the light to 1, the meter shows 9.75 volts and increases from there.

I am trying to control a chihiros led light, I havve 2 of them, one with 99 led's and one with 36 led's, they have an in line jumper that allows you to step down or up the intensity, 7 steps. When I hooked my meter up to the output of the dimmer, it was constant at 12v on its highest setting, but when you went down the voltage went down accordingly but cycled, it was not constant, see this post for dimmer details - https://www.reef2reef.com/threads/r...-on-raspberry-pi.289256/page-441#post-5539596

I did try to take a reading from my meters' frequency setting (20K HZ setting) and this is what it showed:
Full power - step 1 - 0
step 2 - .02-03 cycles from here out
step 3 - .-4-.05
step 4 - .06-.07
step 5 - .06-.08
step 6 - .07-.09
step 7 - .08-.10

Yeah I as just wanting to control the intensity throughout the day along with the time, I can order the pre-made controller but somehow would like to know if that is the answer before hand. I did try both PWM pins from the pi and they should the same results, I'm just trying to figure out where to go from here from a testing perspective to help figure things out.

Thanks for the information and if there is any additional information that is needed just let me know. :)

bishoptf · Jan 4, 2019

crusso1993 said:
If it were me, I wouldn't say I melted the BB. I would say I made some radical modifications!
Happens to the best of us.
Hey - did you happen to check out @Diamond1 build? He worked his OR 247 into it. Maybe he can give you some input with your lights.

Yeah I'm glad it didn't fry anything else like my pi, its a 3 a+, if it had been a zero I would not have cared, I can get them for $5 from microcenter and probably should get one of those to test with, then it's not a big deal. The 3 a+ are only $19 but $5 is a little more tolerable. :)

I'm do like to tinker and do stuff so ya just have to keep learning and moving forward. :)

bishoptf · Jan 4, 2019

Ranjib said:
I use the exact same circuit as I described in the lighting controller guide. Its based on n channel logic level power mosfet, and its driving a 12W , 12V led strip, a moonlight, which is use sporadically.

Yeah but you didn't get the smoke effect :)

Is there anywhere I can read about or look at the code for the PWM stuff, I know when I google pwm and pi there is a good bit of information, and just wasn't sure what the code was passing to the pi behind the scenes. Scratching my head right now trying to figure out where to go from here...

bishoptf · Jan 4, 2019

Since I love to void my warranty ;) I opened the small led unit, looks like I did the soldering work, lol :)

Bigtrout · Jan 4, 2019

Tom Bishop said:
Since I love to void my warranty ;) I opened the small led unit, looks like I did the soldering work, lol :)

Ok, they are standard 5730 led strip lights in the fixture.

First question, im assuming the power supply is 12v? When you put the npn mosfet inline, you put it on the negative line in to the fixture?

bishoptf · Jan 4, 2019

Bigtrout said:
Ok, they are standard 5730 led strip lights in the fixture.

First question, im assuming the power supply is 12v? When you put the npn mosfet inline, you put it on the negative line in to the fixture?

Correct the power supply is 12v. I had it connected as it was laid out in the diagram above, https://learn.adafruit.com/assets/2693 It's no longer getting hot, etc, it just doesnt appear to be varying the voltage like I thought it would. When I move it to 1 it starts at 9.75v and goes up. I have not hooked anything up to my fixture, i only had my meter connected to the pwm outlet, I wanted to see what the voltages were doing before hooking anything up, trying to play it safe and not fry my China led. :)

Ranjib · Jan 4, 2019

Tom Bishop said:
Correct the power supply is 12v. I had it connected as it was laid out in the diagram above, https://learn.adafruit.com/assets/2693 It's no longer getting hot, etc, it just doesnt appear to be varying the voltage like I thought it would. When I move it to 1 it starts at 9.75v and goes up. I have not hooked anything up to my fixture, i only had my meter connected to the outlet, I wanted to see what the voltages were doing before hooking anything up, trying to play it safe and not fry my China led. :)

whats your pwm frequency ? try to lower it and test...

bishoptf · Jan 4, 2019

Ranjib said:
whats your pwm frequency ? try to lower it and test...

That might be what I am missing where do you set the frequency, I might have missed something in the settings. I looked for a guide on what each setting did in the lighting section but couldnt find one, like active high/active low. I had it set under the profile to fixed, min-0, max-100, start - 0 and then was playing with the slider, where is the frequency set?

nevermind, I found it oun the settings page, zzzing...I will lower it to 50 and see if that changes anything.

:)

bishoptf · Jan 4, 2019

;Woot;Woot;Woot;Woot;Woot;Woot

That doesnt even come close to expressing how elated I am at the moment, going down actually made it stay about the same, however going up started lowering the voltage and I could see on my meter it started to vary the voltage OMG

I will need to do some more testing on the existing setup to get the ranges for each step so I can try to get close to what they have. So far I have found that setting the frequency to 320 appears to be giving me close to the same results that I remember. At a setting of 10 it was swinging the voltage from ~4 to 6, maybe not as quickly but that is something I will also verify with the existing dimmer jumper.

The big question is how do you dial it in or do you just play with it like I am doing to find a frequency that appears to work best? I can't tell you how excited this is, this is all with the breadboard so will have to solder it up but I think I am close. I'm still concerned about the amperagee, and pulling the +12v from the hat, thinking of pulling the +12v directly from the input and running each +12v to each outlet. Grounds still need to be taken back to the pi but this is my initial thoughts right now.

Pretty stoked now to say the least :)

dmolavi · Jan 5, 2019

Will I need one of these to interface to my ReefBrite fixture: http://www.reefbrite.com/product/led-line-dimmer/ (the single channel since I only have one RB light).

If so, I'm ready to pull the trigger and order parts...

pickupman66 · Jan 5, 2019

Tom Bishop said:
I am using this diagram - https://learn.adafruit.com/assets/2693 which is from this guide - https://learn.adafruit.com/rgb-led-strips?view=all#wiring
The article talks about using a TO-220 fet and lists this one - IRLB8721, my local electronics place did not have that particular fet but he had this one which should be as good IRLZ44N, another TO-220 low level logic fet. Right now I have no load I just have my meter connected to the output and I see constant voltage, it's no cycling at all and when I set the light to 1, the meter shows 9.75 volts and increases from there.

I am trying to control a chihiros led light, I havve 2 of them, one with 99 led's and one with 36 led's, they have an in line jumper that allows you to step down or up the intensity, 7 steps. When I hooked my meter up to the output of the dimmer, it was constant at 12v on its highest setting, but when you went down the voltage went down accordingly but cycled, it was not constant, see this post for dimmer details - https://www.reef2reef.com/threads/r...-on-raspberry-pi.289256/page-441#post-5539596

I did try to take a reading from my meters' frequency setting (20K HZ setting) and this is what it showed:
Full power - step 1 - 0
step 2 - .02-03 cycles from here out
step 3 - .-4-.05
step 4 - .06-.07
step 5 - .06-.08
step 6 - .07-.09
step 7 - .08-.10

Yeah I as just wanting to control the intensity throughout the day along with the time, I can order the pre-made controller but somehow would like to know if that is the answer before hand. I did try both PWM pins from the pi and they should the same results, I'm just trying to figure out where to go from here from a testing perspective to help figure things out.

Thanks for the information and if there is any additional information that is needed just let me know. :)

I bought one under the Fzone name for my son's freshwater tank. The one I have does 10 timed settings and a % for each. It is a simple two wire circuit from the controller up to the led. I haven't looked more into it though to be able to really tell you what is going on.

Ranjib · Jan 5, 2019

dmolavi said:
Will I need one of these to interface to my ReefBrite fixture: http://www.reefbrite.com/product/led-line-dimmer/ (the single channel since I only have one RB light).

If so, I'm ready to pull the trigger and order parts...

w00t :-)