# 240v to 12V Conversion



## HairyKiore (Jun 14, 2010)

Hi...I want to power up some Car 12v Headlights ....(3 to 4 Sets) to provide light in my Greenhouse.. ...However I do need a power converter and have found some on Ebay... 240V to 12V 60A PSU .....at around US$90 ....

http://www.ebay.com/itm/AC110V-220V...hash=item1c6199bb0a:m:mNLXsCdgXeErFrhxwWhUa3g

They state for LED Light strips but wouldn't the 60A one run a few car headlights ....I welcome a expert opinion on this...My very limited electrical knowledge tells me it should....AS I understand a Pair of headlights would require about 10 -12Amps ......Thankyou for any help ....HK


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## cwwozniak (Nov 29, 2005)

You could have a problem with the inrush current within the first fraction of a second when power is first applied to a filament type headlight. This can be about 5x or more the nominal operating current. If the power supply can handle this inrush current then you should be ok. If the power supply shuts down instantaneously upon any overload, you have a problem.


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## Drabdr (Nov 26, 2007)

If you had four lights that would be 260 watts. At 12 vdc, that is equivalent to 22 amps. Note you will need to get some #12-#10 wire to carry the signal; and you will need a good ground.

Not to squelch your home improvement idea, but you can purchase a 250 watt outdoor (weather resistant too) at Home Depot for about $20.00.

http://www.homedepot.com/p/Workforce-250-Watt-Halogen-Portable-Work-Light-778-980/202071327


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## HairyKiore (Jun 14, 2010)

Hi..I am being advised by a friend in Canada ...he sort of disappeared but Skyped me today so I showed him the postings...He assures me everything will be oK....I am going to get a Fusebox with the harness/wiring and the light switch from a car that will be in the wreckers yard ...Re Home Depot ....Wonderful place as I visited a shop in Los Angeles in 1996 ...Unfortunately I live in New Zealand ....Of course by using car headlights I have been told with the right bulbs I can reproduce Full Spectrum light IE 2500K to 7000K which will help the tomatoes I am growing....Regards HK


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## john1 (Nov 25, 2000)

Hi Hairy, a car headlamp of the filament type would typically be at least sixty watts, most of them probably a little over a hundred watts.
If you are going to use old headlamps from a wreckers yard to light up a greenhouse, then it would be nice and bright, it would also give quite a bit of heat.

However, they will run just as well on AC as they do on DC, so you dont need a "Power Supply Unit" as you describe.
You really only need a transformer.
And they dont worry much about brief surges.

SAFETY
------
If you're doing this stuff by yourself, or on your own, then get it checked by someone knowledgeable before you make it live or fire it up.
I would suggest trips, a greenhouse doesn't sound like a safe place for too much electrics.

Regards, John


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## Drabdr (Nov 26, 2007)

john1 said:


> Hi Hairy, a car headlamp of the filament type would typically be at least sixty watts, most of them probably a little over a hundred watts.
> If you are going to use old headlamps from a wreckers yard to light up a greenhouse, then it would be nice and bright, it would also give quite a bit of heat.
> 
> However, they will run just as well on AC as they do on DC, so you dont need a "Power Supply Unit" as you describe.
> ...


Good points. I would say, though, that since the goal is to run in a certain cycle-band, I'm not sure if those lights would run on the same cycle using direct AC voltage.


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## HairyKiore (Jun 14, 2010)

Hi..Rest assured I am getting advised by an expert but he does "disappear" now and then......With vehicle fuse box and harness and light switch (I have access to a wrecker yard and can get these at any time but I have to remove them myself pnly if the vehicle is in a safe position) ...He will then supervise via skype by video etc in the routeing and wiring of everything ....For this to work the bulbs are most important so as to get a full spectrum of light ..I have been told I need incadescent (2500K) for the red at a 3 to 1 ration to a blue (6500) which apparantly will cover the full spectrum...Looking at LED Grow lights one can see the ratio of red and blue)..I have been assured that a PSU 110-230 to 12V 60A 720W is available on Ebay for rountd NZ$120 Free Shipping.. that would do the job...Regards Ron


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## HairyKiore (Jun 14, 2010)

http://www.trademe.co.nz/building-renovation/electrical-lighting/other/auction-1060067956.htm

Hi..I have found this on the NZ online auction........I welcome an opinion on this ...it says 84VA ...and as you know I am looking for 60A at over double the price ...if these units can be rectified to produce 84A I could buy two ...but there must be a catch or is there...Needless to say I would be over the moon if these produce 84A of 12v power...Thanks Ron


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## cwwozniak (Nov 29, 2005)

Sorry to cut short your trip over the moon. VA stands for Volt-Amps, which is voltage multiplied by the current. For a DC output, it is equal to watts. For an AC output (which is what the device puts out), the actual output wattage will be less, if you have a capacitive or inductive load.

In your case with an incandescent lamp load, you could use the AC output as is, with a 7 amp maximum load (84/12=7).

EDIT: You may wish to reconsider using some of the options suggested by others instead of automotive headlights. I don't think that anyone mentioned that standard tungsten and halogen headlights have relatively short operating lives, as compared to fluorescent and LED lights. A high output halogen headlight might last a few hundred hours while CCFL and LED bulbs are rated in thousands of hours.


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## HairyKiore (Jun 14, 2010)

thanks for the explanation re VA....Actually I contacted the seller ( via the auction) so one cannot exchange personal details....he confirms that the PSU is useless to me BUT thinks he has something that could help me so I have to recontact him in a week via the auction..Why car lighting ..well I have considered CCFL and LED bulbs in fact I have used these inside my house for propagation ...and grow lights which are terribly expensive and too many people have been caught out buying these. Lighting my greenhouse is useless unless it covers the Full Spectrum or close to it and covers a 4 metre by 5 metre greenhouse with strong light...I was told that using incadescent bulbs (2000-2500 K- Red light ) at a ration of 3 to 5 with a 6500 K bulb (the blue light ) would basicly give a full spectrum of light in my greenhouse ..It could require some "bulb tweeking" for best results but it would work.. I never realised the bulb life was so short but even if I build up an array of red and blue LED,s I still need a PSU to to power them ... What great forums on Tech Guy ...I am learning a lot due to the responses ....Regards Ron


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## HairyKiore (Jun 14, 2010)

HairyKiore said:


> http://www.trademe.co.nz/building-renovation/electrical-lighting/other/auction-1060067956.htm
> 
> Hi..I have found this on the NZ online auction........I welcome an opinion on this ...it says 84VA ...and as you know I am looking for 60A at over double the price ...if these units can be rectified to produce 84A I could buy two ...but there must be a catch or is there...Needless to say I would be over the moon if these produce 84A of 12v power...Thanks Ron


Its no good...


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## john1 (Nov 25, 2000)

Hi Hairy, If you want to provide full spectrum lighting for your tomatoes,
then yes you are quite right, incandescents will fall short at the top end.
This can be made up by strip lights, or by those newer type of LED/PHOSPHUR car headlights.
Strip lamps will work on normal mains supplies, but those newer types of LED lamp will need a DC supply.
Fortunately the efficiency of those new LED types is so high that the light output is many many times more than the incandescent types, which get hot and the LED types don't get hot.

Which is distinctly in your favour because a DC power supply is only needed for the newer type of LED lamps.

Look at the wattage consumption on the side of the LED type lamps, my guess is that it will be in single figures.

So i would reckon a small moderately priced 12v.dc. power supply for the LEDs, and a reasonably priced 12 volt transformer for the filament type lamps, and a normal mains supply to suit the strip lamps, if you think its wanted.

Check this out with your expert, and see what he says.

Regards, John


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## HairyKiore (Jun 14, 2010)

John ..My problem is what are strip Lights ...Even after checking on Wikipedia I have no clue what they are unless they are known in my country under another name ....Its the Kelvin that is much more important to me than the wattage ....Maybe it would be simpler if I just find an LED Array circuit for lighting a greenhouse ..buy the appropriate LEDs from Ebay ..join them together and plug them in ?? If only I was a lot younger ??..........Thanks


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## john1 (Nov 25, 2000)

Hi Hairy, Strip lights.
Well my apologies, they are more correctly known as 'flourescent strip lamps'
but ive always called them strip lights.
They used to be all over the place, here there and everywhere. They were for many years the cheapest form of proper lighting.
There are still many around, but they are being replaced as they fail with the newer LED types.

They come in various lengths from about a foot to about eight foot (maybe more but not commonly) They give a very decent light and are used in greenhouses i think more for young plants.

They usually have a 'fitting' or 'unit' which contains the electrics to run the lamp. They usually need a second or two for 'warm-up', and they usually have to have a brief voltage 'kick' to start them.

They are still fairly common here in UK, but every year sees less of them.
You can still pick them up here for next to nothing.
Unless you want a new tube for your fitting at home, then suddenly the price is strangely high, almost like someone wants you to buy their new LED version.

Regards John


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## john1 (Nov 25, 2000)

Hi Hairy,

Just been looking up some of that Kelvin Colour Temperature stuff.
Did't find much about the newer type LED lamps, but i reckon they go a lot further into the blue than other lamps.

You may find that using incandescent types and LED types will adequately cover the range you want, and you may not need flourescent tubes at all.

Best of luck with it,

John


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## HairyKiore (Jun 14, 2010)

John..I have been doing a lot of reading too.....I do have some 5 foot LED Tubes ...I must check what K they are.....Now I was in a charity shop the other day and they quite often have unused CFL bulbs for $1 each or 50 cents on a special day ..I got two 20W bulbs and it occurred to me that I should check the "bulb box" out each time I visit and keep buying these ..By the next season I could have enough cool whites and warm whites and they would cover the 2500 to 6500K .....it seems too me this leaves the extreme red K under 2500k ...Now I am elderly and electrics puzzle me or I would be making a grow light array etc myself ....but I could get something like RED LED Strip lights from ebay (China w/Free Delivery) or just RED LED Bulbs to get the under 2500K seeing this is the frequency really paramount for the fruit and ripening...I see on some Grow lights the ratio is 5 Red to 1 Blue.......
I have a large freezer stripped of its door and anything of value....got it for $2 from a scrap merchant ..a steel as its lined with stainless and I use it for an "incubator" for my propagated seeds when they are first transplanted in small containers.....With eight 5 foot Fluoro lights (adjustable hanging) above I thought my young plants looked great and then I transplanted them into growing bags and they went outside into the greenhouse .....where they have not done very well at all but apparantly it has not been a "tomato season" as its been the same for a lot of people this year....Being right down the south of the country I think lights would be a huge plus for my greenhouse ....Regards Ron


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## HairyKiore (Jun 14, 2010)

John..Hope you do not mind but I have found TWO HP PSU in what I think is a server.....I am rather excited about them but could be wrong ...they appear to be both rated at 47A.....and if that was correct it would give me 94A of 12 V....So I will post Photos and see what you think......Cheers Ron


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## john1 (Nov 25, 2000)

Hi,
Yes, they should be fine.

However, the 47 Ampere rating might be an absolute maximum,
but even 40 should meet your needs.

Brief caution,
I have seen in the past people take the output leads and quickly spark them
together, to produce a visible display of output.
They will often then say somthing like, there that shows its working.

You may have seen people do this yourself.
It used to be somthing people would do on battery chargers.

I would often go to great lengths to point out the damage that this can do.
But i would be told, dont worry i always do that.
Or its Ok, its just a quick check to see that its working.
Or the best one, thats too quick to do it any harm.

Please dont do that to either of those power supplies.
That can easily cause extensive internal damage.
Those power supplies are "Switching type" power supplies
and they are very complicated inside.
If anything goes wrong with them, they will not be easy to repair.

*****************

You might have to put little 'dummy' loads somewhere,
in order to trick the power supply into turning on,
read up on it they are a well known unit and many people
use them for all sorts of stuff.

Regards, John


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## HairyKiore (Jun 14, 2010)

John...Today I bought the whole server for $40 ...I took a punt that the 47A was a true rating and it has two PSU's so thats 1150 W.... I bought the complete unit just in case there was anything that the PSU's required in it?? ....I have a lot more respect for electricity than to cross circuit..... ....Under guidance I am sure I will be testing them by my multimeter ...I also take on board your point about the 47A being a Max rating but I am going to be very careful here .... My friend in Montreal will be guiding me ...
A Ford Fairmont has just come into the scrap yard and I have asked if I can buy the Headlights/Fusebox/Harness and light switch ....I will even grab the tail lights if I can....I know i can get the fusebox etc for basicly nothing but I may miss out on the lights ..I hope not ...My friend has it all worked out and I know there is Relay switches involved ..Meantime I am still trying to work out between nm and K and at my age its a minefield .......There is a great tomato website with various forums on everything and growing lights are sure to debated somewhere ....Yesterday I put Tomato laterals I was given into containers with soil in them ...and put them in the incubator under lights...they were withered but within hours they looked so healthy yet they still have to root...it sure showed me what light does for them .....I just have to work out the best way to get the under 2500K or red and it would have to be LED's......but thats down the track......Regards Ron


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## john1 (Nov 25, 2000)

Hi,

Ive just been looking at that picture you posted, not sure if its the server unit or the power supply.
If the power supply is a separate bit, then check to see if those fans are also for
cooling the power supply, you might need to leave them in place to run the power supply.

Filament lamps start surge.
---------------------------
This page explains it very well.
http://www.cyberphysics.co.uk/Q&A/KS5/electricity/characteristic/charlampQ5.html

I will try to include a pic of the graph,
but a visit to the page should make it clear.

Basically, they say its about double the running current,
although in some cases it can be a little more than that.

If you find you are nearing the limit with the surge,
you might be able to 'stagger' the lights to come on in small groups,
or possibly a dropper (series resistor) which can be shorted
after small interval.

Simplest way is to switch them on one at a time, not all at once.

Unless this has some sort of timer unit running,
in which case you will have to see if its Ok.
You might find you are not getting close to the surge limit.

There are various ways,
I'm sure something can be sorted out.

Regards, John


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## john1 (Nov 25, 2000)

Ive been trying to get that pic to come up in the open forum.
But i couldnt find any way.
I'm sure it used to be possible,
but that was a while ago.
It might not be possible any more to put the pic in the text.

**********
No, its coming back to me slowly,
I think it has to have its own url,
then you link it ... i think ...


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## HairyKiore (Jun 14, 2010)

John..Thanks ..I will resend picture and mark the two PSU's then later take complete photos of a PSU......Now there is no way I can set this all up...I am just taking directions from a friend in Montreal and this is my problem ...He is offline and not responding to emails .....So until he calls I am just trying my best gathering everything together like he told me....Now the Fairmont has been taken but thats no problem although I am disappointed..I will get the Fusebox /Harness etc from another car that probably somebody is smashing up as I write...and relay switches...
I have been doing a lot of searching on Ebay ...Its great for finding whats available with photo's etc ......At the moment I am considering two different circuits...Its just an idea and Later I will get it checked out.....I just feel that LED's are the way to go ...LED bulbs are cheap to buy and cheap to run ...they can be bought at various colour temperatures which means one could experiment with the lighting just by changing bulbs ...So I need to get some advice on this from a gardening forum but heres my idea if I have my reading correct......I could put a circuit in for the 2500 to 7000K lights ....that whai I think grows the leaves flowers etc ....but when the fruit arrives it needs the red spectrum under 3000K to ripen them ...which could be on a secondary circuit.....but so far I have not found any car bulbs under 2500K .....but this has only stirred my curiosity in the actual Headlight bulb it seems to me that LED's are clustered on a stem ....I have seen some that are obviously soldered ..others there is no way to tell but I thought can these diodes say at 6500K simply be replaced by another diode the same except that its kelvin is red ie round 2000K ......well I would not have a clue but I am trying to find out...plus i also found listings for special "grow" diodes ... which could open up other possibilities....At my age I have to keep the brain running?? Regards Ron


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