Could Use Some Transformer Help

[Zenster]

Hey all,
I can't find any reading lamps that are configured the way I like (from a design and attach standpoint), so I'm rolling my own.

The bulbs I've bought are these linked here:
https://www.superbrightleds.com/mor...d-led-ceramic-tower/1633/#/tab/Specifications

They'll run anywhere between 10VDC and 30VDC, so I'd like to set them up as dual intensity using a dual-output transformer.

I'm hoping someone can point me to the best kind of transformer to use with this bulb that would have a primary of 120VAC, and two secondary outputs of perhaps 12VDC and 20VDC.
The secondaries can vary a little as long as they stay within the rating of the bulbs.

At only 140mah current draw, the transformer can be anywhere from around 200mah output to maybe 500mah output. I'd like it to be as small as possible to fit into a custom housing, so I don't want to over do it's power rating and let it get too large.

Any suggestions?
TIA

 

[CoveAxe]

so I'd like to set them up as dual intensity using a dual-output transformer.

It says right on the specification page that this isn't dimmable. What you are wanting to do isn't going to work.

The input voltage range just means that it will work as designed between those voltages without needing a converter or anything in between. It's going to be the same brightness at 10V or 30V.

 

[Zenster]

Well then, you can see why I asked for some help.

I clearly thought that brightness would depend upon the lights' input voltage.

That cleared up, I'm not married to dual brightness. I only thought it would be nice.

That might make it even easier because all I really need is a simple 120VAC in with a 12VDC out (likely the most easily found), so I'm guessing that the size of the transformer would be even smaller.

So is that it? All I need is something basic like this?: https://system.netsuite.com/core/me...&c=ACCT126831&h=8e708e5bdb83047769e8&_xt=.pdf
Or would something like this be better?: http://www.premiermag.com/pdf/PNK-10010.pdf

It appears to quite basic, but will it play nice with the light I linked?

 

[frank70]

The bulb's a replacement bulb for an 1156 automotive backup light. Yes, that's quite a bright bulb but you'll need 12Volts DC to light it. Instead of just a transformer, you'll require a 12VDC power supply that can supply a quarter amp or so (i.e.: transformer/rectifier/filter capacitor, or for more efficiency and smaller size, a small switching supply). They are quite common and inexpensive, shipped as a wall-wart with many electronic devices that need 12VDC.

I have no idea how that bulb would react to AC power; curiously, it's rated to also work at 12VAC, so I guess it's worth a try, but very strange for an automotive bulb. Would probably flicker, which I'm not sure would be conducive to reading. I still think you'd be better off with a DC supply.

 

[CoveAxe]

If this were me, I'd just buy a power supply that matched my specifications rather than try to design one from scratch (unless I needed some very specific parameter controlled). Other than being cheaper and easier, it's also better peace of mind knowing that it's tested and so it's unlikely to burn down your house.

There's a couple of routes you could go here:
1. Forget the power supply and just get a battery container that holds 8 AA batteries in series. That's 12V and it will last quite a while, especially with some rechargeable batteries. Then just wire it directly to the bulb/socket with a switch. No need to be plugged in or anything. This is also the safest option because at no point is there a high voltage present in the system at all.
2. Use a wall wart. You probably already have a wall wart sitting around your house that fits in the voltage range of your bulb. You could just get a male/female adapter, wire it with a switch, and then directly to the bulb/socket. 2nd safest route since wall warts need to meet approval to be sold.
3. Get a ready-made LED power supply. This is the smallest I could find with a quick search. As long as you make sure that it has some way to dissipate heat and not get too hot, you should be OK. Just wire in input voltage with a switch and then output to bulb/socket. This is your 3rd safest option.

If you're dead set on using a socket to power it, then I think the wall wart is the way to go. This bulb is only about 3W, and it's difficult to find LED-specific power supplies in a small size for that power range, and wall warts are usually designed for low power like that. I think it's going to much safer as well and also easier you practically don't need any space at all.

 

[FRITZHID]

That "bulb" is junk, it will overheat and discolor/fail in long duration use. Get a compact AC/DC LED driver and a single 10w xml2 warm white, drive it at 5-7 watts, face down. You'll squeak with glee.

 

[FRITZHID]

A dimmable driver is easily avail