Multiple Driver Soft On-Set

Quite a few -if not the most- of the Chip-On-Board LED growers ,
that choose the DIY way to obtain their Solid State light fixtures,
choose to use a single driver to drive more than one COB LED array.
While this method is quite simple and of course quite economic,
as they avoid the purchase of multiple drivers ,
like in the case of driving a single COB LED array per driver ,it presents some downsides.

One of them is of course ,that if the driver fails during a grow cycle,
the whole unit will fail to continue supplying those valuable photons to the plant(s).
So,it would be a good idea to have a spare driver ,just in case.

On some other cases ,more than one driver is used to drive a single COB array (per driver),
or more COB LED arrays (per driver).

This thread is made to deal with a certain issue ,presented when multiple drivers are used ,
especially of high output and at the same time experiment with a gradual irradiance level on-set,when the lights are switched ON ,at the very start of each "day" .

In the following NASA research paper ,one can find more information about this "soft on-set" and lots more about other aspects of the lighting used in an artificial environment for plant cultivation.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19960011687.pdf

Still ,let us stay focused on another issue called " accumulation of inrush current " that presents itself ,when high-output constant current LED drivers are powered simultaneously.
At a Meanmwell's "Switching Power Supply Manual " ,

( http://www.adminstrumentengineering.com.au/media/pdfs/Catalogues/Manuals/Mean-Well-USER-Technical-Manual.pdf )

we can read at chapter 2.3 :

2.3 Inrush Current
When AC is initially powered ON, a peak current is required to charge the empty bulk
capacitor. This momentary peak is also called the inrush current.
The magnitude of the inrush current varies according to the type of current limiting
circuit used. S.P.S. commonly uses a thermistor to limit inrush current. The high
resistance of the thermistor limits inrush current at cold start of S.P.S.; the low
resistance of the thermistor reduces power consumption after power-on. Thus, in order
not to accumulate inrush current do not turn the power supply ON and OFF rapidly.
Generally, after turning-off, a delay of few seconds before turning-on is suggested.
Compared to the input current in steady state, the inrush current could be several to
tens of times higher. Be aware that application with multiple S.P.S. leads to accumulate
inrush current. In this case, the ability of input wiring, external fuses, and switches to
withstand transient current should be taken into consideration.

So,the purpose of this thread is for different ideas to be presented in order to overcome such issues.

Those of you that have any ideas ,no-matter if stupid-simple or highly complicated ,
please feel free to express them in as much detail as possible.

Cheers.

A first idea ( but not verified yet if it actually works) ,is following .
It requires some soldering skills and some basic knowledge of analog electronics.
Custom-making Printed-Circuit-Board skills ,are also quite useful,although the circuit can be quite easily made ,by using a "prototyping perforated circuit board ".
This circuit hopefully can switch ON four drivers ,with adjustable delay between them.

Parts List (for 4 drivers) :

- 4x Douple Pole -Single Throw Relays .
- 3x CD4017 Decade Counter ICs
- 3x 2N3904 NPN transistors
- 1x LM555 timer IC
- 2x 47uF ,25 V electrolytic capacitors
- 3x 100nF ceramic capacitors
- 1x 10nF ceramic capacitor
- 3x 1 KiloOhm resistors
- 1x 10 KiloOhm resistor
- 1x 100 KiloOhm resistor
- 1x 1MegaOhm potentiometer
- 3x 1N4001 diodes (in case of mechanical relays used,for transistor protection )

Schematic :


Red lines: +12 VDC
Black lines: Ground ( 0 VDC )
Brown lines : AC Line
Light Blue lines : AC Neutral
Dark Blue lines : Delay timing circuitry
Purple lines: Clock signal

Operation:
This circuit needs a 12 VDC power source to be powered.
It can be a small constant voltage power supply that is used also to power the fan(s) ,
in a DIY COB LED grow light .

When the light is swithed ON ,then the +12 VDC (top left at the schematic) power source is switched ON also.

Two things are happening then:

1 ) The LM555 timer is powered up .
2 ) The first DPST relay (RELAY#1 ) is tripping it's two poles.

Let us see what actually is happening with some more details.

LM555 timer at Astable operation .

An Astable Circuit has no stable state - hence the name "astable".
The output continually switches state between high ( +12 Volts ) and low ( 0 Volts ),
without any intervention from the user, called a 'square' wave.

This type of circuit could be used to give a mechanism intermittent motion by switching a motor on and off at regular intervals. It can also be used to flash lamps and LEDs
and is useful as a 'clock' pulse for other digital ICs and circuits.

Schematic Astable timer circuitry :





LM555 timer Pinout :
U1 intergrated circuit (IC) is the LM555 with its 8 pins .


The 47uF electrolytic capacitor connected at +12VDC power supply ,close to Vcc & RESET pins and the 10nF ceramic one connected with the Control Voltage pin ,
are called "bypass" capacitors and are used to supress "noise" signals .

The 10K resistor ( usually termed as R1 ) ,the 100K with the 1M pot (together termed R2 ) and the 47uF capacitor after the potentiometer ,all connected with dark blue line ,is the "timing circuit " of the LM555.

In order to find the frequency and the period of the square signal output of the LM555 check this calculator :
http://www.ohmslawcalculator.com/555-astable-calculator


When the pot is at 0K position then R1=10 K & R2=100K (C= 47 microFarad )
Using the calculator ,we get as a result ,a period of ~7 sec .

When the pot is at 1000K ( 1 megaOhm ) position , then R1=10 K & R2=1100 kiloOhms (C= 47 microFarad )
Using the calculator ,we get as a result ,a period of ~72 sec.

That means that when pot is at "minimum" position the output (pin 3) is signaling HIGH
( +12VDC ) every ~ 7secs
and when pot is at "maximum" position , the output is signaling HIGH ( +12VDC ) every ~ 72 secs .
That is the adjustable "clock signal " of this circuit.(purple line) .

Relay #1 :




So ,except the LM555 timer circuit that powers On ,once our COB LED is switched On
(thus it's 12VDC Fan power supply also ),the relay #1 is tripping it's two poles.
Pole #2 as it can be seen on the schematic ,will close the AC circuitry powering the first CC driver.
Pole #1 will close a +12VDC circuitry powering the first " CD4017 Decade Counter " IC .
(Red line that outputs from "C2 point of Pole#1 ) .

CD4017 Decade Counter (U2) :




The 100nF ceramic capacitor close to VDD pin of the decade counter ,as you may have guessed ,
is also a noise bypass capacitor.
As the 4017 counter is powered ON ,at it's input (CLK =clock =pin14 ) it accepts the +12 VDC "HIGH" signals
from the output of the LM555 timer,described before.Every time a high signal is detected ,the counter outputs HIGH
(+12 VDC ) at one of its ten ("decade" ) outputs ,starting from 0 to reach output 9.
Every time a new output is HIGH ,the previous one goes LOW.So first the pin 3(output 0) of the decade counter goes HIGH ,then at the next input signal ,pin 2 goes HIGH (output 1) & pin 3(output 0) goes LOW and so on .
Say ,that we have adjusted the timer at it's minimum delay ( ~7 secs ) .It will take then about a minute ,until Output
9 (pin 11) of the counter to signal HIGH . If we had adjusted the timer at it's max delay (~72 sec ) then it would have taken about 10 minutes until the pin 11 went HIGH .
When pin 11 (output #9 ) goes HIGH ,then via the 1K resistor ,the transistor Q1 closes ,like it was a switch.
NPN transistor means that it's "middle" semiconductor is positive ,accepts + VDC signals ,while it's two ends
( Collector & emitter ) are "negative" ,thus connected to "GROUND" .Once the transistor closes ,it connects the Relay#2 with the Ground .The latter being already ,connected with the +12VDC source ,now it's tripping it's poles.
With an adjustable delay of about 1 to 10 minutes ,since the first relay tripped.

CD4017 IC package pinout :
( note : Vss pin =GND/ground - VDO pin =VCC )

Relay #2 :





Now, Relay #2 is tripping it's poles ,with an adjustable delay between ~1 to ~ 10 minutes,
since the LED light was switched ON firstplace.Let us see what happens from this moment and on ....
Pole#2 of the relay #2 ,switches ON the second LED driver.
Pole#1 of the relay#2 ,does two things now :
a ) Of course, it switches On the second- in the row -decade counter ( U3 ).
&
b ) It transmits a HIGH (+12 VDC ) signal to the CLOCK INHIBIT input pin ( pin13) of the first decade counter (U2).
CLOCK INHIBIT input ,when goes HIGH ,it inhibits the signals reaching the CLOCK input (pin 14) of the counter.
That means , even though if the CLK input is continuing receiving signals from the LM555 ,the outputs of the counter
do not continue their "cycle" (notice also that the RESET-pin15- is connected to GND ). The decade counter holds at HIGH state it's last output (number 9 ,pin 11 ) .Thus it keeps Relay #2 to be closed continuously .

From this moment and on ,the whole procedure described ,keeps repeating,up to the last relay in the row,
(until all relays are closed ).

Further Notes:

- Accumulated Inrush Current ,from powering ON multiple -high power- LED drivers can easily deteriorate
the contacts of mechanical timers or the contacts of mechanical relays used inside the digital timers.
Thus the timers in an instance , may fail to switch ON (very rare ),
or fail to switch OFF (very common ) .

-Accumulated Inrush current may fry the internal parts of EMI filters ,burn fuses,melt the insulation of wires and/ or destroy the contacts of switches ,also.

-A " soft on-set " of light irradiation will aid the plants to avoid light and water stress,
as also may aid reducing the delay to starch production, all caused by rapid exposure to high irradiation levels.

-The above circuit presented is actually very easy to make and very cheap (probably less than $10 ).
(Thing is that let's hope it works ,too... )

- Using above circuit presented,with it's present timing configuration and for 4 drivers ,
the minimum delay from first driver switching On to the last one to switch On ,
is about 3 minutes and the maximum delay is ~30 minutes .

Sounds like a great idea!

Will need to read through this later..

I will admit most of this is way too technical for me but I have what I believe could be a simple solution for you. Maybe lol. I read a topic by supra i believe where he wires two drivers of different current in parallel. In his post he talks about using switches to turn drivers off to conserve energy during veg and possibly even ramping up the power as needed by turning on the weaker driver only, then stronger driver only, than both. Using the same principal you could put each driver on a separate timer of your choice and simply have one timer turn on a half hour after the other, while timing both to turn off at the same time. Something tells me that's way too simple of a solution and not what you're looking for. Probably because I didn't understand your question lol.
I thoroughly enjoy reading your posts and learn something new every time. I would like to ask you a question on topic. Is there any reason you can't use drivers of significantly different currents? In the test I believe supra used two lower power drivers so that each combined were under 700ma. But would it be possible to say start with a 200ma driver, then add a 1200ma to equal 1400ma?

ShyGuru said:

I will admit most of this is way too technical for me but I have what I believe could be a simple solution for you. Maybe lol. I read a topic by supra i believe where he wires two drivers of different current in parallel. In his post he talks about using switches to turn drivers off to conserve energy during veg and possibly even ramping up the power as needed by turning on the weaker driver only, then stronger driver only, than both. Using the same principal you could put each driver on a separate timer of your choice and simply have one timer turn on a half hour after the other, while timing both to turn off at the same time. Something tells me that's way too simple of a solution and not what you're looking for. Probably because I didn't understand your question lol.
I thoroughly enjoy reading your posts and learn something new every time. I would like to ask you a question on topic. Is there any reason you can't use drivers of significantly different currents? In the test I believe supra used two lower power drivers so that each combined were under 700ma. But would it be possible to say start with a 200ma driver, then add a 1200ma to equal 1400ma?

Click to expand...

Brilliant. Soft start dedicated leds! The other way is quite hi tech though...

ShyGuru said:

I will admit most of this is way too technical for me but I have what I believe could be a simple solution for you. Maybe lol. I read a topic by supra i believe where he wires two drivers of different current in parallel. In his post he talks about using switches to turn drivers off to conserve energy during veg and possibly even ramping up the power as needed by turning on the weaker driver only, then stronger driver only, than both. Using the same principal you could put each driver on a separate timer of your choice and simply have one timer turn on a half hour after the other, while timing both to turn off at the same time. Something tells me that's way too simple of a solution and not what you're looking for. Probably because I didn't understand your question lol.
I thoroughly enjoy reading your posts and learn something new every time. I would like to ask you a question on topic. Is there any reason you can't use drivers of significantly different currents? In the test I believe supra used two lower power drivers so that each combined were under 700ma. But would it be possible to say start with a 200ma driver, then add a 1200ma to equal 1400ma?

Click to expand...

Look...
I 've to admit that I admire Supra very-very much .
He is a pioneer in so many aspects .
Still , I do not agree -or at least I'm not keen - with few of his practices.
Not something personal,I insist on that one .
I've learned myself a lot from him !

The reasons that I "disagree" with few of his practices,
are purely based on a different view-perspective ,that I 've of certain things.

One of them ,is that I would avoid connecting the outputs -if I've understood correctly- of constant current drivers.
It may work out well ,but it may not also ,as the drivers may be "confused" at "reading " the load and "overshoot" ,voltage-wise.
Generally speaking ,i'm not a man of "risks* " in certain matters.
Especially with high-quality ,expensive equipment and parts .
Still,my "solutions" usually are rather complicated and "over the head " of quite a few people.
(And just imagine ,that comparing to -for example-Guod's skills & knowledge basis ,
what I present is rather "Stupid-Simple" ....)

* I love extreme sports like BASE jumping for instance ,
but I would never use Kapton tape to "secure" the COBs on the heatsink .
...LOL ,But I never use elevators ,too ..Quite afraid of them,actually ....

Disclaimer:
Supra ,my dear brother and friend ,I hope that you'll not get angry or disappointed with me .
Every man is allowed to have different perspective of things ,
as also to exercise noble and polite " criticism " .... xxx ... ...

Cheers.

Oh! I see now that I did completely misunderstand the question lol. I thought you were discussing using multiple drivers to power a single cob, but it appears maybe your question was about controlling the dimming of several drivers at once. OK I'll butt out now but I'll keep following along so I can keep learning. Thanks for all the knowledge you continue to share.

Oops..i read that quickly and thought it was just a extra driver and led. It could be a crude way to do it. Maybe a few extra "outdated" cobs run at low current passive. Have them turn on with a seperate timer for the first 15min or so.

I discovered that I had already some parts of the circuit readily available .
Soon,I'm going to make a PCB and going to test the circuit,at a grow LED light,
featuring 4x Meanwell HLP-60H-42 drivers ,which will drive a Vero 29 each one of them .


Instead of a ceramic capacitor a MKT capacitor can also be used (blue).
Instead of 47uF electrolytic a 100uF can also be used (green )-
Caution:Only the "bypass" one ,NOT the timing one.The timing one has to be 47uF .
A DPST mechanical relay ,opened up .
You can see the two pole contact pairs and the triggering coil mechanism ,just behind them .
Behind the caps ,is a LM555 timer IC (DIP package) .


The physical size of the 2N3904 NPN transistors( TO-92 package ),
compared to CD4017BE Decade Counter ICs (DIP package) and
the 1 kiloOhm resistors ( Through-Hole ).

2N3904 NPN transistor pinout:

The schematic presented is already corrected & updated .


IMPORTANT NOTE ABOUT THE RESET (PIN 15) OF THE DC4017BE DECADE COUNTER IC

The RESET pin ( #15) of each CD4017BE decade counter ,
has to be brought LOW to ground (GND ).

If left not connected (NC ) it " floats" and that means it may ,at an instance ,reset the counter to output 0 .



IMPORTANT NOTE ABOUT THE PROTECTION OF 2N3904 TRANSISTORS

In case of mechanical relays are utilised ,it is advised to connect a diode near the triggering
12 VDC supply of the relays ,those controlled by the transistors.
The "flywheel " diode ( 1N4001 ) will protect the transistor from inductive load " kick-back" currents.
If solid state relays (SSR ) are used those diodes are rendered obsolete.


http://www.electronics-tutorials.ws/transistor/tran_4.html

Does the soft-set rule out PWM control? Or this that something else in pipeline...

I guess I am too green at this, but why cant we ramp up drivers on a RTC shield...I guess I am intrigued by the older Typhoon controllers and do realize that most of the ramping functionality seems to be on multiple channels rather than a single circuit....
Is using a microcontroller too unreliable in case of resets or something similar as well?

I wanted to ask earlier, hope I didn't hash the thread all up

Abiqua said:

Does the soft-set rule out PWM control? Or this that something else in pipeline...

Click to expand...

Nope..
The drivers in the circuit presented are controlled at their AC side .
PWM control is done at the DC side of the driver (.... Dim + & Dim - ....... )

Abiqua said:

I guess I am too green at this, but why cant we ramp up drivers on a RTC shield...I guess I am intrigued by the older Typhoon controllers and do realize that most of the ramping functionality seems to be on multiple channels rather than a single circuit....Is using a microcontroller too unreliable in case of resets or something similar as well?
I wanted to ask earlier, hope I didn't hash the thread all up

Click to expand...

Myself , i trust that ,the more complicated a system,the more the subsystems it "contains " ,
the more delicate the whole operation of the system .More "fragile" the "balances" .More parts included ,
most of times with different "tolerances" of different kinds .More parts included also means that even from a single humble resistor ,to the most advanced multicore -core CPU,more the chances of a part to be defective by manufacture level and to "misfire " very soon ,at any moment ...

Maybe ,i'm being too "old-schoolish " ...
Ok ,even so ,I'm entitled ,too ..

Furthermore ...
Fixing a " fail " ,or replacing a defective part ,to some stupid-simple-level electronics that you've made yourself ,
is somewhat different of doing so with hm ...you know ...even Arduino ..All that tiny SMD electronics at the board ,even if you have traced which one has to be replaced ...Ok ..Let me see you do it ..I can't and i do not want to ...
New board ...$30 .... vs New relay $3 ,for example ....

I dunno ,maybe i'm having a "simplicity " crisis ,lately ...


Anyway ...
The circuit seems to work ,fine or not exactly ...
Some things where missing ...
And they where "weird cases " of operation ...
(Abnormal operation )


Here is an enhanced version ..
It needs more parts ,but seems to work more than fine .


- in this version ,the base of the transistor is held down to ground ,via 1K + 10K =11 K resistor .Until outpout 9 signals +12 V ,the base of the transistor is held low ,and the transistor is "locked " open ,as a switch .No mishappens there ,anymore .


-Also the CLOCK INHIBIT input ( aka ENABLE ) is held also down to ground (0V ) ,
by the 10K res . No "mishappens" there- from being tied to a +12V signal output ,
but actually remained " floating "( not 0 V,until signal was HIGH " .
..damn this cellphone ,radiophone ,TV ,satelite,cosmic energy and
other E/M radition vast "ocean" of ..hm .."waves" ."Floating "..... get it ? ........- ,

-the HIGH signal to CLOCK INHIBIT now ,is provided by OUTPUT 9 itself
and not from the -previous in the row -relay -more precise timing this way ,
as there no added delay from the relay coil-mechanism -contact tripping ...

-More " bypassing " caps used ,far better the circuit stability .

- Last relay is Single Pole -Single throw .SPST .

-Place The 1N4004 diodes if mechanical relays are used.
Relay's current draw at the +12 VDC "control" side better to not exceed ~50mA .
(2N3904 max current as switch =100mA )

Thus relay( s ) of of 12/0.05 = 240 Ohm resistance or higher (up to ~four times = ~1K ) should be used .
At the AC side should beat least " 4 - 6 A @250 V ",for each .

Cheers

All good SDS, I am a big believer in "to each their own" and I admire your work and your knowledge. The main reason I promote the kapton method is for those who drilling and tapping is a barrier to entry. I do promote COB holders for those who want a professional appearance and are not intimidated by the metal work. With Kapton, Wago lever nuts, Pico EZ mate, Veros and a CPU cooler with TIM on it, a DIYer can slap together an awesome COB grow light with no drilling/tapping/soldering/stenciling etc, a painless process

As far as combining drivers to boost current, it works great and is very stable. I use it everyday as my family room light. The drivers I used cost $1-$3 each so it was just a small experiment with not much at risk. An interesting result but for the larger grow lamp systems I am in the process of switching over to Mean Well because I want the 94% efficiency.

One data point to add, I have never had a problem with starting a bunch of cheap of drivers all at once. Each of my boards draws about 10 amps on a 120V circuit, 25 drivers turning on at the same time, every day for more than 1 year with no problems so far. BUT by switching to Mean Well HLG it will only be 7A or 3.5A if I switch to 240V.

The circuits above after some testing done ,seem to be pretty unstable ...
...

But ...

...

There's a new one however,that tested and seem to works rather exceptional .
...

Actually it's a kind of a "module" ..
Quite a few of these modules can be "linked" together (connected in series )
and control as many devices (LED/COB Drivers ,CO2 system ,Ventilation,etc with an adjustable delay
amongst them .

The schematic & parts per module :


-The finished modules ,measure about 40 mm x 65 mm in pcb surface .

-It operates very-very stable and error-free.

-It has half the price of an cheap such module ,sold on E-bay or elsewhere.
And is made of high quality parts for such price.
i.e. Texas Instruments I.C.s & Schrack Technik relays by TE.

-Two indication LEDS either track the "HIGH" clock signal (COUNT -blinking red ) ,
or either indicate that OUTPUTs are ON/ACTIVE (constant green ).

-A " Double Pole Double Throw " relay is needed.
(The ones used have about ~345 Ohm resistance ,thus they draw j ~35 mA ( 420 mW ) . s
Specs: 12 V spoule / 2x NC - 2xNO _ 250V ,8A .

-Each module draws ~15 mA max (180 mW ) when in COUNT state and as soon the relay "trips" :
COM(MON ) pin now is connected to NO(normally Open ) pin
and the NC (normally closed )pin is not connected to COM anymore.
When at OUTPUT ACTIVE state it draws about 55mA max (660 mW ) .

-Modules are linked like that :
12 PSU ====>module#1 INPUT===>Module#1 OUTPUT ===>Module#2 INPUT and so on ...

-In case of a single module ,it can delay the onset of both an AC powered device and a +12VDC powered device .

-Timer sub-circuit switches OFF automatically ,
when relay trips .


^^^ 3x modules in series connected ,
sharing the same board ...

^^^Home-made printed circuit board ,
with sourface mounted (SMD ) resistors & ceramic capacitors (both 1206 SMD package ).



All it has left is to implemented into a led light ..


Cheers.

stardustsailor said:

The circuits above after some testing done ,seem to be pretty unstable ...
...

But ...

...

There's a new one however,that tested and seem to works rather exceptional .
...

Actually it's a kind of a "module" ..
Quite a few of these modules can be "linked" together (connected in series )
and control as many devices (LED/COB Drivers ,CO2 system ,Ventilation,etc with an adjustable delay
amongst them .

The schematic & parts per module :
View attachment 3390969

-The finished modules ,measure about 40 mm x 65 mm in pcb surface .

-It operates very-very stable and error-free.

-It has half the price of an cheap such module ,sold on E-bay or elsewhere.
And is made of high quality parts for such price.
i.e. Texas Instruments I.C.s & Schrack Technik relays by TE.

-Two indication LEDS either track the "HIGH" clock signal (COUNT -blinking red ) ,
or either indicate that OUTPUTs are ON/ACTIVE (constant green ).

-A " Double Pole Double Throw " relay is needed.
(The ones used have about ~345 Ohm resistance ,thus they draw j ~35 mA ( 420 mW ) . s
Specs: 12 V spoule / 2x NC - 2xNO _ 250V ,8A .

-Each module draws ~15 mA max (180 mW ) when in COUNT state and as soon the relay "trips" :
COM(MON ) pin now is connected to NO(normally Open ) pin
and the NC (normally closed )pin is not connected to COM anymore.
When at OUTPUT ACTIVE state it draws about 55mA max (660 mW ) .

-Modules are linked like that :
12 PSU ====>module#1 INPUT===>Module#1 OUTPUT ===>Module#2 INPUT and so on ...

-In case of a single module ,it can delay the onset of both an AC powered device and a +12VDC powered device .

-Timer sub-circuit switches OFF automatically ,
when relay trips .

View attachment 3390995
^^^ 3x modules in series connected ,
sharing the same board ...
View attachment 3391004
^^^Home-made printed circuit board ,
with sourface mounted (SMD ) resistors & ceramic capasitors (both 1206 SMD package ).



All it has left is to implemented into a led light ..


Cheers.

Click to expand...

So what are we looking at again, a home-made driver set or?

Looks complicated. I bet you had few kicks after putting the work and effort into it.



Yeah, I'm not a fan of the Kapton tape either, at least not for holding up COBS. Drilling and tapping does take big boy toys and a little extra time but damn, if that finish don't look legit.

I'm sure I'll find a way to implement the leftover tape into the next project (holding together wires or something along those lines ).

What's next, O' Sailor?