I have a Halogen desk lamp I want to convert to LED to use on my flashlight work bench.
(The light is an ALEX light Serious Reader, an expensive reading light from the UK) like this one: https://www.seriousreaders.com/products/classic-range794/classic-heavyweight-table-light
(mine looks exactly the same but it’s the older version with halogen instead of LED)
The power supply circuit board is fried so I want to convert/upgrade it to LED.
So I need a “switching” transformer or “LED Driver” to replace the burned out halogen transformer.
(I’m in the USA and the old power supply was 110v to 12v, the halogen bulb was a 12v / 6watt)
It was the dimmable version so I’ll need to change the momentary rocker switch to an on/off one.
I need to know if these power supplies are the correct type I need? and would one be better than the other?
Looking for any advise or info to help with this project.
In the description for that led mr16, it mentions that it has it’s own driver, which means you just need to supply it with 12 volts, if I’m not mistaken.
It will be pretty bright and dimming would be nice (they do make the bulb in “dimmable” version) but I figured it might be to complicated for me to include dimming. I’m no expert on these things (reason I started this thread) but I feel confident I can do the work once I get the proper components.
The way the dimming worked before was what I would call “ramping”? that is it used a “momentary” rocker switch, you would hold the switch down and release at the desired output level. I was going to have to swap out the rocker with an on/off for the non-dimming upgrade.
What is a PSU? Power Supply Unit? And I assume you mean for dimming I would need a “special” one?
So if that is the case could I still use the power supplies I linked? or would I need something different like a standard “non-switching” unit? (I’ll need a new power supply because the original 12v supply is fried)
Yes the bulbs have current-limiting drivers inside. All LED bulbs do. You could use a 1A or 1.5A or 10A AC-DC converter and the bulb would only use whatever current it takes to get 9W output (dunno what kind of efficiency those things have).
I thought about that for a minute however I was concerned about the wiring, the leads going up to the light head (also houses the on/off switch) are very thin, look like about 22ga but they are marked 300v. So maybe I could do it this way (just run the 110v right up to the switch and bulb with no additional transformer?
I have not messed with the MR16 stuff, though I have built my own E27 bulbs from parts. Looking at ebay, there are listings that claim to show 110VAC MR16 bulbs, but they are rare. I was too quick earlier and didn’t notice those were 12V AC drivers.
You can use a flashlight driver with this. Convert the LED wiring from serial to parallel. Then connect the LEDs to a NANJG-105c or similar current-limited driver. Power the circuit with a 5V/1A to 2A wall wart. The on-off switch can be used to switch modes.
Any plain 12V PSU would do. Comfychair is right, probably 1.5A would be fine for a 9W bulb. That’s what I was trying to get at above, but I was too brief.
A flashlight driver doesn’t seem like a good match. For one thing, there’s a big COB LED in the bulb from the OP: it can’t be reconfigured.
For dimming I’d probably do something a bit too DIY for beam0’s comfort. Note that the updated LED model linked in the OP is only 3W. I’m sure that I’d do whatever I could get away with from a heat management perspective. For the driver I’d likely want to roll my own - totally irrelevant in this conversation. Instead, maybe the TaskLED H6CC would be a good choice. It accepts a potentiometer for dimming, so it would work well with a knob. It’s buck, so a 12v PSU would be fine. A cheaper option might be the LDRADJ-3A which zpinch recently pointed out. It’s also buck, so still fine with a 12v PSU, but instead of a potentiometer it seems to be intended for one of those rotary switches with off/low/med1/med2/high. Both options also support PWM dimming if you want to get crazy.
Either the H6CC or the LDRADJ-3A would be fun and folks here would hold your hand through the process. The trickiest part might be figuring out how to get an LED/optic/etc mounted and heatsinked in the existing head.
Or just skip all that and purchase a standard 12v MR16 power supply with dimming and a ‘standard’ dimmable LED MR16 bulb and call it a day!
EDIT: oops, I almost forgot to point out that a cheap CC/CV board might also be a great option with an external pot added. The kind with the detent could still switch the whole thing off. Again, buck driver so it would just be used with a normal 12v PSU. For under $3 you can’t go wrong. (!?) Now that I think about it I’m pretty tempted. The only thing stopping me is that I always just want more light in my work area. Dimming is a pretty rare need for me.
I have a 10W COB LED, LM2596 DC/DC converter with the onboard pot replaced with a 10K external, powered by a 12V wall wart, on an 1/8” aluminum plate stuck to the underside of the shelf above my keyboard. It never gets turned off, just dimmed down to 0%.
Gotcha, thanks this is great advise, because somewhere around here I have several of those
Thanks for confirming, I’m now seeing a lot of bulb choices between 6.5w and 9w at Lowes and Home Depo.
So with these I can source everything locally.
—
That sounds like a reasonable deduction, I’m now looking at the 7-9w bulbs that are around 500 lumens, and many are dimmable. With a non dimmable set up I can keep the conversion simple and see how it works for me, I can get the standard on/off rocker switch from Digi-Key
…then if I decide I want dimming later I can just swap out the power supply and add the proper switch/Pot.
I’m glad I came here for help, now I have an idea of what direction I’m heading with this and have learned about several options. I wasn’t real sure if this kind of stuff was discussed much here but now I’m seeing it is very much.
They are all multi-led (4 and 6 LED) opposed to the single led ones I was first looking at.
All are 3000k, and are labeled “Bright White” or “Soft White” I’m hoping they aren’t too warm but my experience with the household LED bulbs is they appear cooler than ones in flashlights.
Can someone please confirm that even though the 12v bulb will be “COB” will have it’s own driver, I could still use either one of these (LED driver/switching) transformers?:
Either will work fine, they are just controlled voltage power supplies.
EDIT: As long as you’re only driving one mr16, for multipes you’d need additional supplies or one rated for higher wattage. Far as I could tell it’s only one mr16 but I thought I’d mention it anyway.
