LED Work lights for milling machine

[BazyleParticipant @bazyle]

Just a thought. A normal 24v machine transformer is run between 2 phases of the 3 phase. If run off 240v maybe it gives a more convenient level.

[Chris HeapyParticipant @chrisheapy71135]

All lights in my w/s are LED now, I converted the 20w halogen flexi lamp to LED by using an AC led bulb so no other work on the psu was required. I made another bench lamp from a DC LED MR16 bulb using a length of brass tube and some turned alloy endcaps. My old Anglepoise lamp I have over the lathe was converted using an LED bayonet fitting bulb made by Philips. I have 5 other 20w equivalent LED MR16 bulbs inset in various places which used to have halogen bulbs, so overall the power savings are considerable.

[URL=http://s970.photobucket.com/user/ChrisLX200/media/Tools%20and%20Engineering/P1020534_zps6e4bd73c.jpg.html][IMG]http://i970.photobucket.com/albums/ae183/ChrisLX200/Tools%20and%20Engineering/P1020534_zps6e4bd73c.jpg[/IMG][/URL]

[Donhe7Participant @donhe7]

Posted by peter walton on 16/04/2013 10:16:07:

To get rid of the strobe effrct you will need some capacitance smoothing added.

If the amps are quite high then a lot of capacitance will be needed.

Peter

 

Just a little bit late with my post, I hadn't read the posts following Peter Waltons, and the purpose of my post here has been covered in subsequent posts, so is "surplus to requirements"!!! …………. please ignore it!!

As he is using 24v AC, he would need to rectify it first, then measure the DC voltage (It could possibly be 36v DC, after rectification and fitting of a capacitor to smooth the DC), then adjust the LED units so they have approx. 12v DC across each module, other than that, he would need to fit a fairly substantial resistor in series with the LED units so that their current ratings are not exceeded, with resultant shortening of their life

donhe7

Edited By Donhe7 on 20/04/2013 15:25:05

[Sub MandrelParticipant @submandrel]

Although descibed as constant current devices, LEDs are surprisingly effective voltage regulators. This is why they go pop, as the volatge increases the current increases very rapidly trying to drop the voltage down.

If unsmoothed Ac doesn't pop the LEDS smoothing its houldn't make it worse. In the former case the peak voltage will be 1.4 times the RMS value and the LEDs are probably passing a hefty peak current 100 times a second. Add the capacitor and though the smoothed voltage appears higher, the peak voltage shouldn't be any higher, anmd may be lower as the capacitors may be reducing it.

The source resistance of the power supply will have a big influence here, especially if the power draw is close to its limit.

Poking around with a scope on the unsmoothed and 'smoothed' supplies might be interesting, or has anyone here got a SPICE simulator?

Neil

[John Stevenson 1Participant @johnstevenson1]

Posted by Chris Heapy on 20/04/2013 08:42:11:

All lights in my w/s are LED now, I converted the 20w halogen flexi lamp to LED by using an AC led bulb so no other work on the psu was required.

Chris,

So nice to see you back, you were sorely missed when you let the advert site die.

[Les Jones 1Participant @lesjones1]

Hi Neil,
I do not agree that an LED could be described as a constant current device. It needs to be driven by a constant current source. (Or from a constant voltage source a few volts above the LED voltage with resistor in series of such a value to give the rated current for the LED.) I agree with the rest of your post pointing out that LEDs behave very much like a zener diode. Your comments regarding the effect of the peak voltage of the rectified AC particularly with a smoothing capacitor is why I suggested to John that he added a series resistor. I think we both understand the characteristics of LEDs. I am just being pedantic about calling a LED a constant current device.

PS The other 10 Watt LEDs I ordered have arrived today. Unfortunately the sent the 9 – 12 V version rather than the 28 – 30 V version  I ordered.

Les.

Edited By Les Jones 1 on 20/04/2013 18:39:55

[Sub MandrelParticipant @submandrel]

Hi Les, yes I meant that describing them as constant current devices (rather than neeeding a constant current) is lazy and inaccurate; it wasn't my clearest post though!

Neil

[Les Jones 1Participant @lesjones1]

Hi Neil,
After making the comment about the the term constant current device I had a thought that I may have used the term in the way you used it in my previous posts. Other than that I think your post made it clear that some thought has to be given to driving LEDs from rectified AC (With or without a capacitor.) The peak current rating is not very much higher than the average rating. (Unlike quite a few semiconductor devices.) When white LEDs first became available I thought they would be good for a stroboscope but the low peak current rating made them less suitable. The 10 Watt arrays now available would probably work OK as even with a 1% duty cycle the average power would still be 0.1 W (Or a little higher using the peak rating.)

Les.

[John Stevenson 1Participant @johnstevenson1]

Latest installment.

 

Somewhere on page two Les made reference to those ring LED's called 'Angel lights'

Seen these used before where people clip them round the quill but they wouldn't suit me as i struggle sometime having the head hard up to a big dividing head doing splines.

When I looked though i found some 140mm ones, sounds big but they will just fit round the housing of a Bridgy head so clear of the dividing head.

 

Also saw somewhere on a forum where a guy had built a ring light and found out the tool was always in shadow, which makes a lot of sense but being big might get by this.

 

So sent for a couple.

 

 

Machined an alloy ring up with three steps in it, one to fit the casting, one for the ring light and one to retain the clear perspex cover to protect it.

 

 

Wire it up to a 15v wall wart at 400ma off an old power tool and this is taken at night with no other lighting on in the shop.

 

 

It does throw some shadow when the quill is down, virtually none when up. Can be easily removed by one screw and it does give a useful general light off.

With this and the earlier one with the two panels I can now dispense with the angle poise type lights which I hate with a vengeance.

Edited By John Stevenson on 29/05/2013 00:43:57

[Ian S CParticipant @iansc]

Bought a mains powered 10W LED worklight to replace the 500W incandesant one that I had been using. Plugged it in, and the RFI was terrible, I tried a ferrite ring on the power cord, no good, thought about taking it back, then tried a small isolating transformer, BINGO, no noise. Ian S C

[The Merry MillerParticipant @themerrymiller]

Just received my two 48 LED panels from China.

Found a 12v-1 amp plug-in psu that used to provide the power for an old Netgear modem.

Hooked up the panels in parallel and they work a treat.

I have them on soak now in the kitchen, I'll give them a couple of hours to see how warm they get then look at ways of packaging them prior to attachment to the mill.

Len. P.

[Rik ShawParticipant @rikshaw]

OO'ER this is all very laboratory speak. I think I'll stick to one of these – – – – – Rik

[Michael GilliganParticipant @michaelgilligan61133]

Rik,

Despite all the interesting experiments and speculation … these 48 LED panels are designed as Car "Dome Lights" [Interior Lights], to be run from a 12volt Lead Acid Battery. They come with a range of adapters, to fit different Bulb Holders; or you can discard the adapter and just use the wires.

It really doesn't get much easier: Pretty much any nominally 12volt Battery will run one of these panels for a while.

MichaelG.

[Author]

Posts