As silence doesn't seem to be essential and there is plenty of room to
hide them I'd use old computer ATX PSU's. They have the advantage
that they can be switched on and off easily using the low voltage
control built into them.
I've got a spare DPS 750 server PSU (details at
This will supply 12V at 36 Amps all day so about 350 of your bulbs. If
you are using the full 750W the fan is loud, at half load it is pretty
quiet. It also has 5V and 3.3V outputs also at 36A max (but total
load must stay less than 750W).
It is big - 12 x 12 x 30cm and fairly heavy - 5kg
If its any use you can have it for the price of the postage (which
should be less than £10). I can do the wiring mods for you.
Thank you for all the replies. I now understand why an LED power supply
will be unsuitable.
However, this is brilliant :
I must have at least 4 old desktops here, not used for years. I'm
guessing they will have power output printed on the label. I confess I
did not know breakout boards existed. So, a power supply from an old
PC, a board like this :
The answer to a maiden's prayer. I assume two wires, connected to 12v
and GND, will supply all the little 12v bulbs I need, all wired in
From memory, the power supply will come out of the PC complete with
'kettle' mains socket, cage, fan etc. all in one.
That should do it. However you should watch that the 24 pin 'ATX' connector
has a limited current rating - I'd budget about 5A per pin. There's only
two 12V wires on the ATX connector so 10A available.
Most of the 12V current is intended to be supplied on the 'EPS' and 'PCI
So you might use the above breakout to supply other voltages and switch
the PSU on, and then snip off and solder yellow/black wires to access more
Yes. The outputs should be on the label. Note that some PSUs are split
rail (12V1, 12V2, etc) so it's best to not to join outputs from different
looms if you need more current.
 The official Molex pins are rated at 9A, but safer to assume they've
underspecced the wiring (and to avoid pins getting hot).
LED power supplies are mostly constant current supplies, incandescent
bulbs require constant voltage. The LED PSUs voltage can vary
considerably as they try to keep the current stable (ish). A constant
current PSU will have a specified output current much lower than its
wattage rating would indicate - as you increase the load it increases
the voltage. The rated current is fixed, the rated wattage is fixed,
the voltage will vary to maintain the rated current within the power
maximum. If you connect bulbs in parallel to the PSU then as bulbs
fail the PSU will ramp up the voltage to maintain the current at a
stable level. Incandescent bulbs really dislike over voltage so they
will all start failing rapidly.
For example a typical constant current LED drivers provides 700mA
output in power ratings of up to18W. It will automatically set the
current output and allow the voltage required vary automatically to
cover voltages from 3 - 54V as the load varies..
I've used lots of these for all sorts of jobs including driving
electronics and motors in the same job. They are current limited and
behave very well.
The most recent one is powering a lift to raise a 1/4 tonne machine from
its storage position to operating bench height based on the works from a
motorised golf cart.
A good cost effective PSU solution.
Yes it was an interesting project and a great sense of relief when the
first lash up managed to lift my own weight with quite a small
proportion of the PSU current being drawn!
I wrote it all up for a woodworking forum but since the decision of
Photobucket to apply extortionate charges that I refuse to pay, the
photo links are all broken.
I'll try and dig out a working link to a video I took of it running.
Here are the photos
and the text is here
they are sort of in order. Hope you can make something of it.
Unfortunately my broadband is so slow here that I can't get to all the
pics in a sensible time, but from the thumbnails it looks pretty
impressive (and a lot of work). I talk about projects like this but
there's a never ending list of things to do on the "new" house so
engineering projects are shelved for the time being. I got the (2 tonne)
lathe and (1/2 tonne) mill into the workshop this week (after far too
long under tarps) but have now decided I want the lathe against a
different wall so lots more jacking and rolling are needed - bu&&er!
Glad you could make something of it.
I've now fixed the forum links for the photos and as the forum auto
scales the pictures it might load faster for you.
Now I'm retired and time -rich I can embark on projects like this.
Good luck with machinery move and hope the rust has not crept in under
the tarps. My myford lathe and VMC mill are quite modest by comparison
but still not relishing moving those anytime.
Not to be read at meal times!
It got attacked by a planer (a different one). Tendon transplanted from
my leg, skin from my forearm and flesh sourced from the next door
finger. The surgeon sewed the damaged finder to its neighbour which gave
the transplanted flesh a blood supply (called a cross finger flap).
Whilst in that state, bandaged (and bored), I joined a different
woodwork forum with the user name "9fingers". A few weeks later, the
finger were separated again but if I had changed my user name to
10fingers, it would have led to even more questions!
The (female) physio seemed a little taken aback when I said I really
needed my foreplay finger working again!
12 years on my hands are fully functional but I still use the user name
"9fingers" on a number of forums.
Well you did ask....
An enjoyable 30 minutes has just been spent reading your project
write-up - very impressive! I don't know how long it took, but it might
have been faster to extend the workshop ;-)
One of the photos showed parts of your extraction system - I'll start a
separate thread on the subject in the hope that you can describe what
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