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Branded laptop power supplies are usually very stable, so if you have these, one laptop supply and buckpucks for whatever voltage you need would work great.
Reef Pi Build
- Thread starter Diamond1
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b4tn
Valuable Member
@Ranjib
The problem with most wall warts is, who made them, can you look up specs? With most you can not other than what printed on them. I suspect that most wont put out a good steady voltage at their rated current.
I am a service engineer for a high end cnc machinery company, and their machines only use 2 brands of power supplies, IDEC and Meanwell, if they trust them for critical machinery, I trust them for my aquarium
That being said, the mountable power supplies have much better specs, but if you are having trouble with a build that would be hard to change from a wall wart, Meanwell makes some wall warts with good specs, but they are relatively expensive compared to the RS line of power supplies. Most branded laptop plug in supplies are good but then you need to step down with an lm2596.
At first I used Samsung 5v 2amp wall warts because they were laying around. Upon testing with just a pi zero, and 8 relays on a relay board all powered on, I watched voltage dip from 5.1V to 4.85V. And it would fluctuate while turning relays on and off. The meanwell stayed at 5.099V no matter what I did.
This is what I use. I think it’s from a dell. It’s a 12 volt 5 amp power supply from a laptop. We where throwing boxes of them away at work so I grabbed a couple.
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Good score!
Jonathan Troutt
Well-Known Member
Hold on, are the relays 12v or 5v - earlier in the thread you put 12v relay, but the above seems like its 5v?
Think i'm going to give this a pass sadly, too many components with voltage changes and things I simply don't understand! - thankyou for the effort though, the more I read the more confused I get so probably not a great iea for me to be messing with my only light!
Doesn't help that im in the UK and most components you linked aren't readily available e.g the relay is this one - without a "high / low" - whatever that means, that your link has
https://www.amazon.co.uk/ELEGOO-Channel-Optocoupler-Arduino-Raspberry/dp/B06XK6HCQC/ref=sr_1_6?s=electronics&ie=UTF8&qid=1548153511&sr=1-6&keywords=5v+relay&th=1
Edit: Its also going to cost £60 ($78) (and I already have the pi)
I cant understand why if the Pi has PWM control, I cant just splice into the PWM wire/s on the light and use the pi to control that(and keep everything else inside my light unit)
I don’t remember which light you have but with viper spectra’s the driver inside required a 12v signal to turn on the drivers. From there you can control the brightness with the pi’s PWM.
Now for the driver on/off control I used the darlington Chip vs using separate mechanical relays. A transistor is basically an electronic switch. And the darlingtons we use in these builds are logic level voltage controllable and able to source 500ma per darlington pair. (Correct me if I am wrong on that spec) To me building it this way was simpler although @Bigtrout had to help me out with the wiring cause I had it butt backwards.
Now for my power supply I use a 20v lenovo laptop charger that outputs almost 4 amps. Then I use buck converters LM2596 to give me what I want.
@Ranjib
The problem with most wall warts is, who made them, can you look up specs? With most you can not other than what printed on them. I suspect that most wont put out a good steady voltage at their rated current.
I am a service engineer for a high end cnc machinery company, and their machines only use 2 brands of power supplies, IDEC and Meanwell, if they trust them for critical machinery, I trust them for my aquarium
That being said, the mountable power supplies have much better specs, but if you are having trouble with a build that would be hard to change from a wall wart, Meanwell makes some wall warts with good specs, but they are relatively expensive compared to the RS line of power supplies. Most branded laptop plug in supplies are good but then you need to step down with an lm2596.
At first I used Samsung 5v 2amp wall warts because they were laying around. Upon testing with just a pi zero, and 8 relays on a relay board all powered on, I watched voltage dip from 5.1V to 4.85V. And it would fluctuate while turning relays on and off. The meanwell stayed at 5.099V no matter what I did.
Even if you do find specs from a power supply, if it’s an off brand consider them aspirational. It’s super cheap because it’s mostly cut corners
I’ll add TDK/Lambda to the list of trusted supplies. If a company isn’t in the business of just selling power supplies, it’s likely a rebadged job - certified power supplies are expensive to take to market, and no one wants to pay more than they have to, letting everyone chase cost and quality down a never ending spiral, with the random brand deals sold on Amazon near the bottom of that barrel.
I have nightmares of off brand batteries and supplies, including off brand power supplies that under no circumstances would pass conducted emissions testing in the US making them totally useless for anyone.
What I have been doing is to check the adapters are regulated and Ul listed
b4tn
Valuable Member
Either relay will work fine. You just need to adjust the voltage source to match what the relay requires. If you ordered 5 volt relays and already have a 12 volt power supply you will just power them with 5 volts instead. I copied @Diamond1 's circuit for my lights but used 12 volt relays but either will work.
OP
OP
Diamond1
Valuable Member
@Jonathan Troutt is using a different method of achieving the same thing. You should have no problem switching the 12v power supply from the driver off and on with 5v relays. The 12 volt that is supplied from the driver is what the relay is switching off/on, the 5v or 12v rating on the relays is the power required for the relay to function. So using the 5v relays allows you to pull the power required for the relay straight from the Rpi without an extra power supply.
Ok, so now I need to buy a LM2596 to now adjust the voltage going to the relays also....Might be worth me just buying some lights with actual proper controls, i'm 100% going to mess this up - to many variables, different designs, different wiring diagrams, alternative parts, and given the fact I cant actually work any of them out, or indeed know anything about it, i'm relying on peoples guesses, not a great strategy which will more than likely see me without a working light.
Cheers for the help so far, however, that is massively appreciated.
Cheers for the help so far, however, that is massively appreciated.
What? He just said the vipars need a 12v feed to turn them on? (I have the vipars) I cant run 12v from the Pi as that's 5v? so Id need 2 x LM2596? heads about to explode - I have no idea what im doing.
crusso1993
7500 Club Member
@ph123uk
What's more fun than confusing the bejeebus out of an English bloke? NOTHING!
FWIW - @Diamond1 and @Jonathan Troutt are both right with how they did their lights. However, IMHO, Diamond1's schematic is a simpler one to follow with less soldering and less points for possible failure. If you'd like, you can go to Jonathan Troutt's build here ( https://www.reef2reef.com/threads/troutts-reef-pi-build.521247/ ). Page 6 is where he begins on his lights and runs through page 10. I have to warn you, though, while you may learn a lot, you may also become more confused. I would hand draw a diagram for you so you could see how everything is wired using relays and a small description of the "why" and "how" each part is used. Unfortunately, I do not have the time to do that right now. Hopefully, @Diamond1 will be able to chime back in and give you more detailed "how and why" directions.
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Diamond1
Valuable Member
Like I said earlier if you don't feel comfortable doing the mod on your lights you probably shouldn't.
With that said I'll try to explain exactly what needs to happen to control your lights if you do decide to mod them.
With your light fixture just the way it is the timer controls the on/off function of the lights and the brightness/intensity of both channels (blues and whites).
Each one of these channels has a driver that controls each channel independently.
Both of the drivers have 4 wires that plug into the timer/control board inside the fixture this allows you to control timer functions and intensity of your lights via the timers programing.
There is:
1 wire = ground
1 wire =pwm
1 wire = 12v (the 12 volts comes from the driver and is supplied from the power cord connected to the fixture)
1 wire = off/on (this wire when connected to the 12v wire from the driver turns the fans and LEDs on in the fixture).
(see first picture below)
To connect those wires to reef-pi for control of the fixture you need to do the following.
1. Connect the ground wires directly from the driver to the ground of reef-pi.
2. Connect the PWM wires directly from the driver to the reef-pi pwm using gpio 18 & 19 one gpio for each channel (PWM is what allows you to ramp the lights up and down)
3. Connect the relay to reef-pi using 2 gpio pins from reef-pi (I use gpio 20 & 21) this allows you to turn the relay off/on in effect turning the fixture and the lights off and on. You control the times that the relays turn your lights off/on with the timers in reef-pi.
4. You need to connect the off/on wires to the center terminal of the relay and the 12v wires to the normally opened terminal of the relay. When you turn the relay on it closes the circuit and turns your lights and fans on in the fixture. Think electronically controlled light switch.
For reference here is a picture of the inside of a Vipraspectra showing the wires coming from the driver that you need to tie into to get reef-pi working.
Here's a detailed look at the wiring going to the relay. Where it says channel on the left it should read DRIVER.
The 12 volt, on/off, PWM and ground wires come directly from the drivers. Hopefully this makes it easier to understand the concept.
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Diamond1
Valuable Member
Correct. Those relays should be able to control 120v AC safely.
Jonathan Troutt
Well-Known Member
You will be just fine!! We all got faith in ya. If you need help just let us know!!
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Diamond1
Valuable Member
Agreed!
There are lots of folks here that will help out. When you get all your parts, start a build thread so it gets more exposure to more people who can help out with diferent parts of your build.
