Noob from England

Hi Robert,

I must say that the feedback from you and others on this site is amazing. Thanks for the information, I'll search shortly. Not 30 minutes ago I ordered Canna Terra. I read Mono's journal - he seems to focus on huge yields from one plant (I'm assuming his name relates to his penchant for single plants rather than something he caught from a misspent youth). I digress; he swears by Canna and is also in the UK.

I got a great deal on garden supplies as there was a buy 4 get 1 free deal, but I can't mention the supplier ;-)

I also got some seaweed extract as I've read about great results using that. I want to keep my first grow relatively simple.

My biggest challenge right now is the air system. I want to control fan speed, but cheap controller burn out the fan. I'm dusting off my electronics skills and trying to work out if I should go variac or pulse width modulation. Did I mention my thoughts on doing a full control system driven by a Raspberry Pi? I already control LED lights around the house from my 'phone via a web page on the Pi so hooking it up to relays and sensors shouldn't be too tricky.

Thanks again

Max

ps - I don't think I said how impressed I was you immediately picked up on where the name came from. It is derived from my name and cannabis culture. But you knew that ;-)
 
Morning again Max :)

For simplicity, Variacs are great, and in the case of a fan, even if a fault occurs in the Variac windings, it won't damage the fan, it will just allow it to run full power.

My experience/knowledge of digital controls is limited and dates back almost 20 yrs LOL but I am in the process of learning and re-learning how it all works as I am working on a 1000W LED driver design for my own LED lights.

I like my Mars II 900, but have come to the conclusion, that I can build a more powerful light for comparable money :)
 
Hi Robert,

That's a great goal. I confess I started looking at individual components but wasn't confident I could get hold of the exact wavelength LED's. By the time I'd found all the bits and invested in a good spectrum analyser to verify, I'd be still in the planning stage. I'd be very interested in hearing how you get on with that.

I got a great deal on the Mars II and I'm happy enough for now. I noticed someone in the Mars thread did a spectrum analysis and claimed they don't match the manufacturer's claims, however the grow results speak for themselves so I refuse to be disheartened with my purchase (which is shipping from China tomorrow.

As for controllers; good ones come in around £90. I could build a PWM device for under £10. I've got some feelers out with an electronics engineer who has been building industrial control systems with AC fans since before I was born. If it turns out PWM is good would I be allowed to describe how to build one on here if I don't say where the components came from? Electronics go by generic part numbers so it wouldn't be tied to a single supplier. Fully understand if this would annoy sponsors selling £90 (~$130) controllers.

Best wishes

Mark
 
No worries Max :)

If you are interested in building a PWM control and want to share the details, do it as a separate thread in the DIY forum :)

For my power supply, I have looked into both Varics to control input, and PWM for output, so I can make the lights variable output. Variacs are more efficient that a 2 coil transformer and are adjustable, but for digital components like LEDs, they could blow the whole system if a failure in the coil took place LOL

Decisions, decisions LOL cost and complexity vs component safe guards LOL

If I could find a sure-fire failsafe to protect the digital components, I would go the variac route for simplicity and cost LOL
 
LOL you and me both, I have looked at a number of things to go between the variac and the digital components, but I am having trouble finding info regarding current vs survival times for LEDs. Because LEDs current draw is directly dependant on voltage supply, and because its a logarithmic relationship rather than linear, a small increase in voltage creates a large change in current.

If the survival time was on the order of 10-20ms or more, a simple fast acting fuse would work LOL

Without the info, I have to reply on experimentation and not sure I am willing to risk a $100 COB to test LOL
 
LED's are always dimmed using PWM. If you're driving from a stable input not controlled with the variac (ie stable 12v or 24v PSU) then they will be adequately protected. You never want to change the DC input for LED's. I happily use £10 PSU's on my LED's and have been running them for 6 years. I have £5,000 of LED rope light and controllers around the house and not had any problems with power.

Or am I missing something with what you're doing?
 
Lounge_Christmas.jpg


Here are the lounge LED's
 
Hey fellow UK grower welcome to :420:! Im on my first grow to all the people here are supper friendly and helpful!
Cant wait to see your garden start to grow.

Now is this the same Max Headroom that had a unscheduled tv appearance that one time??
 
OK maybe further explanation LOL

What I am looking at are 200w CREE COBs made up of an array of 42 5w CREE X-Lamp chips. These COBs are rated at 42-46vdc at 4.5amps. The chips (not in an array) are rated at 1.5amp max.

Maybe I am wrong, but it is my understanding that current draw is dependant on forward voltage (or in the case of a matched driver, supplied voltage) and that reducing the voltage, reduces the current draw and thereby the output of the LED.

Therefore, I could use a tapped transformer to reduce my AC voltage to 46vac prior to rectifying to DC and run a full 200w no problem. I could then put a rheostat after rectifying and use that as a dimmer but at the sacrifice of wasted heat (wattage) in the rheostat. I have seen many do this.

I could also use PWM which is a common way to adjust output to digital devices.

By using a variac, I can adjust the AC output prior to rectifying (say from 0-46vac), thereby controlling the DC supplied to the LEDs and therefore the output.

The reason for looking into this as an option, is not because I can't buy a 200w driver, but rather that they are not cheap (they cost about double what I can buy the COBs for), I have yet to find a variable one, and driving at max wattage reduces the life of LEDs. Also, this route, if viable and although old school, reduces the cost significantly. A 1000w driver built this way, is less than the cost of an off-the-shelf 200w driver.
 
Hi Robert,

I get it now. Unless the LED's have some internal driver chips that do something different to all other LED's I've played with (and I have a bit of an LED obsession) then the only way to dim is using PWM, not voltage. I *think* the voltage range is just what they cope with, not a way to dim. Of course, LED tech could have marched on a little but as far as I'm aware PWM is the way to do it. If I can find anything to back this up with the Cree I'll pass on the links. No matter what, it is better to drive the LED's at less than rated; output goes a bit odd at maximum power and chips burn out much quicker. I think Mars drive their 5w chips at 3.5w.

You will notice some dimming by reducing the voltage but it's not recommended. Having said this I now need to research in case things have changed.

Regards

Max
 
Just for a quick reference, the way Mars (or any other maker) keeps the wattage down is by using a lower forward voltage but its not as broad as what I mentioned above.

In the case of the X-Lamps, here is a sample of what I mean:

at 2.7v, they draw 200ma giving an output of 0.54 watts
at 2.8v, they draw approx. 380ma giving about 1 watt
at 3.0v, draw of approx. 1.1 amps and put out 3.3 watts
and at rating of 3.1 volts they draw the full 1.5 amps for 4.6 watts.

now the scale does go higher, in their graph, maxing out at 3 amps and 3.3 volts giving 10 watt output. So you can use variable supply voltage to vary the output, within the 0.5 volts from low to high.

But the higher the amperage, the higher the temperature and shorter the life. They also list the "withstand voltage" as 8000 vdc. So, theoretically, if you could eliminate the heat at the junction point, you could drive them with 1000's of volts.

From what I understand from the data sheets, if you can minimize the difference between ambient temp and junction temp, their is no limit to the drive voltage (output), up to the 8000v withstand voltage.

As with all things digital, heat is the main enemy LOL
 
Lights have arrived! Ordered direct from Mars Hydro in China on Sunday and they arrived today. Methinks they must have UK stock or a private cargo plane. Here goes the unboxing...

IMG_389511.JPG


It's out of the box

IMG_389612.JPG


My eyes! This is bright *orders grow room glasses

IMG_390010.JPG


Excitement mounts. Now to order an extraction/filtration kit. There's a cheap deal on (am I allowed to mention a make?) Black Orchid. Are they any good?

Max
 
Cheers Robert,

It would be great to have you along for the journey. I'm eager to start my journal with all the prep work (seeds, lights etc) but as it will take a month for the tent to arrive, I'll hang fire. I'm struggling to find a local supplier at a reasonable price to get things moving.

I will no doubt keep y'all up to date with happenings and start the journal once everything arrives.


Max
 

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