# PWM circuit help, 24v house lighting system 450w max LED's

#### hp1729

Joined Nov 23, 2015
2,304
I'm making a pwm circuit for leds at 450watts max, i have a few questions and I'm very open for suggestion
in my house i plan to make all my own power for the lights we use, I'm trying to get off the grid but i want to step into this. currently 100% if my heat and hot water are from wood that i cut off my own wood lot,

so a little about the system in planning, the house has a total of 14 rooms, and i wish to run 25watts per room, with 3 rooms getting 50 watts

i bought 450, 1w led's http://www.ebay.ca/itm/50pcs-Brand-...hash=item2c85751197:m:mA9ClcekVcDeTh--R1Ag-ww

I'm a machinist by trade, so I'm going to make aluminum fixtures to mount the leds on to hold them and to control heat also they will be slightly dishes
so the leds are directed in different directions

using 16/2 cl2 stranded wire with a 24 volt system, no more then 25w per line, longest run (1 direction) is 30 feet,
Ill be alright on the wiring of the modules and the switches and my fathers been an electrician for 40 years now so I've been around all that stuff, but I'm new to this type of electronics

i want to build a PWM controller and i wish to be able to pwm the whole system

so I'm thinking

battery bank at 24v
24v into into pwm controller
24v pwm fed into a fuse box as the "mains"
from the fuse box send out 14 lines to each room with switches and led modules in the rooms
plan to do some testing with the leds and figure how many per fixture

most times i hope to have only the lights on we need so I'm thinking probably not more then 150 watts(high end of things) at any given time but i do have 450 leds so its possible it can be that much power

I have made up three drawings mostly compiled of things on found on line, still missing a few parts, you will notice the "T" parts missing and a few resistor values missing, as I'm still undecided on them or have figured them out yet
and input on those parts would be nice, but with poking around and reading data sheets ill be able to get them

im unsure of witch circuit would be ideal for my situation, it will be on and running 24/7, i plan to build at least 2 so have backup's in case needed

On a 24 Volt system 7 lights in series gives you 24 Volts but that is with no current limiting. That is a crude system prone to certain failure. It would work. My flashlight is just batteries and LEDs with no resistors but it works even if I do have to replace LEDs once a year or so.
PWM dimming? I think you will find your lighting too dim to start with. 50 Watts (maybe 700 lm?) is more suitable for a closet.
Maybe 6 LEDs in series and a 350 mA current limiter circuit per lighting assembly. Maybe five lighting assemblies for a 12 by 12b room? Still dim, but livable.
A diffused filter is suggested. Those LEDs might be hard on the eyes without it. White translucent plexiglass?
Build a prototype and see if you can live with it first.
One dimmer for the whole system??? Dimmer in each room? Or no dimmer at all.

#### mcgyvr

Joined Oct 15, 2009
5,394
My flashlight is just batteries and LEDs with no resistors but it works even if I do have to replace LEDs once a year or so.
You and that flashlight again...
Proud of that yearly failure aren't you..

#### mcgyvr

Joined Oct 15, 2009
5,394
I think you will find your lighting too dim to start with. 50 Watts (maybe 700 lm?) is more suitable for a closet.
Try more like 5000 lumen..
A 50W is PLENTY to blind you and light up a room

WARNING: High power LEDs can be very dangerous and you NEVER look directly at the light.. You can do eye damage in seconds..

I fired up my first light I built years ago and only looked at it for 1 second before I looked away.. I saw yellow/blue spots for HOURS after that..
The light was 24 x 3W LEDs..

#### hp1729

Joined Nov 23, 2015
2,304
You and that flashlight again...
Proud of that yearly failure aren't you..
You have to admit it does work. Who am I to judge it. It was designed by an engineer.

#### mcgyvr

Joined Oct 15, 2009
5,394
You have to admit it does work. Who am I to judge it. It was designed by an engineer.
Your definition of "works" is different from mine..

#### hp1729

Joined Nov 23, 2015
2,304
Your definition of "works" is different from mine..

Yes. If I turn the switch on light comes out. It works. A good design it is NOT.
We agree it is not a good design. A good design would cost twice as much and the average customer would not see a difference in function on the store shelf. The bad design is more marketable.
I haven't taken any of the $50 to$100 flashlights apart to see what is in side, Do they have more that just resistors, LEDs and batteries? Do any of them have current limiting beyond resistors?

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