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12 volt LED lighting throughout house

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Dawai:
OUR president Bush made filament bulbs illegal.. discontinued them.. not much luck with the expensive 120 volt LED light bulbs so far. With the 12 volt dc ones, they have been working great.

I put in a solar panel, Used this 100 watt Renogy panel, connected it to a cheap chinese battery charger-minder in the basement. It has voltage monitoring that will turn off a load if the battery goes too low. (suck the bottom from a battery and it does not last as long), A RV deep discharge battery, (largest one I could find)

Looking for lights, I first had bought 120 volt LED bulbs.. lasted less than a month. I tore it apart to see what happened. THEY..seeing each led had a 1.5 volt drop across it, had series wired them all in rails till they got to 120 volts.. trouble is, was.. if one fails they all fail.. (remember the Christmas lights of the 60s?)

My wife and I started deciding what we want in our home, (not a fancy place).
I wanted post type lamps to move around, heavy bottom, selectable diffuser, since the 48 SMD led's are so bright you see burn marks if you stare at them.. harsh light.. hard to read a book by..

I have been learning how to program a arduino, got my first one a couple weeks ago.. IT IS very easy to produce a pwm (pulse width modulated) signal..

Only problem is, not enough current to do any "real work".  SO.. enter the OLD electrician "pass transistor" thinking.. where a small transistor does not go to the load, but triggers a larger transistor..

Ran last night since dusk.. much reduced power, meaning less battery consumption. Thoughts are to monitor battery voltage, have a ac-dc pwr option also to switch to power line current.  We discussed motion timers.. too complicated.. and when I build complication in trouble arises.

Parts, (1)Arduino UNO $12-16, (2)LCDKeypad $12-20, (3)Opto22 Pb4 off ebay cheap, (4)opto22 odc5 module off ebay cheap, (5)48SMD LED array $13 for 5 off ebay. (6)EITHER a transformer-dc pwr, or a battery to drive them. 

Instead of using the keypad to vary the outputs for each room? we are thinking of using potentiometers. Just rolling the dial up and down to dim. Instead of doing lots of control wires, for right now I am going to mount them centrally over the thermostat with the control pots there. (not a big house)

If some of you guys with more experience on the arduino come up with a wireless way to talk, ie remote.. add your comments.. 

FOR you guys with less electrical experience, I can post the code and a diagram if you like.

BaronJ:
Hi Dawai,
I too like the idea of low voltage lighting and agree that a solar panel and storage battery is the way to go.  As far as dimming them goes, I agree that PWM is the way to do it.  You mentioned a pot to control the brightness,  I would simply use a 555 timer and depending upon the load, drive a mosfet.  I bet the whole thing could be built on the back of a 1" pot.

AdeV:
Something else to consider, as well as dimming the LEDs, you could fairly easily wire them up so you can switch banks of them off as a "stepping" dimmer - then use PWM to make each step infinitely dimmable... I think if you found that just running one 12v string of LEDs would be less power hungry than running all 10(?) strings & dimming them. Harder to wire up, of course, but all the more fun for that. By randomly placing your "string", the light would remain even, rather than being obvious strips lighting up.

Ironically, I was planning something quite similar - I bought the panel, charge controller & lights back end of last year. Unfortunately, only the panel has shown up so far, the lights are lost in our useless postal system, and the charge controller hasn't got here from China yet...

awemawson:
When we refurbished our holiday cottages here on the farm, I decided to replace the spherical bayonet 240v incandescent bulbs with LED ones. It was pricey at about £4 per bulb, but long term it should save as the consumption is dramatically reduced and the paying guests inevitably leave all lights on all day when they are out  :bang:


Only problem is the failure rate. As mentioned above, they are wired internally as a string across a crude DC supply, and if one LED in the string fails the bulb is theoretically a write off. Investigation revealed that the plastic hemisphere globe pops off  releasing the pcb disc holding the leds, which are easily unsoldered and replaced. I've now got a large bag of the 'top hat' LEDs and am repairing at least one bulb every week - got it down to a fine art!

Andrew

Dawai:
Don't throw them old LED 120-240 bulbs away, cut them apart.. figure the voltage on each panel, rewire them.

I've not lost one 12 volt one, they burn from dusk to dawn, there was a day when we didn't have sun for several days and they shut off about 4am.. (controller shuts it down) Each 48 draws .2, or 200 miliamps each at 12 volts.

THE 48 LED block is wired together, not going to disturb the wiring-board, it has a sticky tape on the back side. Comes with all kinds of bulb adapters to plug into interior lights in cars.

Last thing I built with a 556 timer, a dual 555 chip, was a tattoo machine drive-points replacer.. with the dual 555's you can alter the frequency and the pulse width.. easily.  On the tattoo rig I had one ten turn pot for each,  AT a big meet, since my tattoo machine ran 1 1/2-2 times faster than everyone elses I made more money.. and that sound, a screaming demon that made all the old tattoo artists look around and try to figure out how I ran it that fast. When the evening got slow, here they'd come, asking questions.  As far as I know, everyone still runs them with points.. it never caught on..

I have the pcb solder mask if you want to have the 556 freq-pwm board made up.. or make it yourself.. 
 I can't see to tattoo anymore, can't see some days how to solder, weld.. or..
either old age, or too many blows to the noggin. They did manage to sell me some $500 glasses.. that work somedays.. other days it is 20/20

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