What are the pro/cons of led driver powered leds vs leds with cap dropper? - Page 1
Forum section: electronics / beginners

author: karapuzo
author_rank: Newbie
timestamp: October 24, 2018, 09:39:51 am
content: Hello all,I have a bunch of 12v Halogen lights MR16, each driven by a 12v transformer.I am looking to replace them with leds, I've found two options, 12v led bulbs (Which need a led driver) and 220v led bulbs that I presume have a built in capacitive dropper.I guess the 220v leds will be easier to install and cheaper (no need to buy drivers) as I just connect the current sockets to 220v and plug in the new led bulbs.What is the benefit of the 12v led bulbs with a driver? Would that be more energy efficient or produce a better light (less flicker?).Also are there any bulbs/drivers that are especially recommended? I have seen a lot of stuff on ebay/ali which varies in price quite substantially.For instance these are the cheapo ones:https://www.aliexpress.com/item/LED-Lamp-MR16-LED-Bulb-LED-Spotlight-Bulb-Lampada-36-54-72LEDs-SMD-2835-For-Indoor/32828234840.html

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: October 24, 2018, 09:53:21 am
content: Not fully related, but I would really advise against plugging anything from Aliexpress that is that cheap into anything near 220V.Capacitive dropper can give you a really poor powerfactor, but in residential nets that usually isn't a big deal. Depending on how lossy your cap is, you can get high losses here (compounded with any losses due to the poor PF causing larger currents).I'm gonna guess nothing from aliexpress is going to score well on the efficiency front. However, good quality transformers/drivers can get quite high efficiencies. Some of them can also easily be dimmed, and will not produce as much EMI as some chopped dimmer.

author: karapuzo
author_rank: Newbie
timestamp: October 24, 2018, 10:25:31 am
content: TheUnnamedNewbie, thanks for the reply.I live in middle of nowhere so my local shops don't have anything local for this socket and even if they had it would still probably be the same shit from aliexpress.I also found some bulbs that are more posh and have built in drivers/protection, like these:https://www.aliexpress.com/item/LED-Lamp-MR16-12V-LED-Light-Bulb-Lampada-LED-Spotlight-ceiling-SMD5050-Dimmable-Aluminum-Chandelier-Light/32878312784.htmlI guess I'll order a few as well as 12v drivers and try it out.I am thinking taking one of these drivers, 10W or 12W, one driver for each bulb, would be easier to wire.https://www.aliexpress.com/item/LED-Driver-Ac-dc-12V-24V10W-15W-20W-25W-30W-36W-45W-50W-60W-80W-100W/32803915535.htmlhttps://www.aliexpress.com/item/ASMTLED-DC12V-18W-28W-48W-72W-100W-Power-Supply-LED-Driver-Adapter-Lighting-Transformer-Switch-For/32828523010.htmlAny thoughts?

author: tooki
author_rank: Super Contributor
timestamp: October 24, 2018, 10:29:11 am
content: Quote from: karapuzo on October 24, 2018, 09:39:51 amI would be very leery of rewiring 12V fixtures to 230V, since doing so may not be safe.But I suspect that the 12V LED replacements are designed to handle 12V AC, since that’s what so many of those fixtures put out. I would look into this. (Edit: a quick Ali search for “12VAC LED MR16” produced many results that expressly say they support 12V AC. So just get that.)

author: karapuzo
author_rank: Newbie
timestamp: October 24, 2018, 11:03:16 am
content: QuoteI've tried this, didn't seem to work.These are the transformers I have, they output 12vac, minimum 10w.The led bulb lights very dimly:Here is the circuitry, it was advertised as 12vac, got it from aliexpress

author: Berni
author_rank: Super Contributor
timestamp: October 24, 2018, 12:58:16 pm
content: These "transformers" are switchmode supplies with no output rectification that output 12V AC at 10KHz. They are designed to drive halogen lamps and it might even be getting confused by the LED load.What you need to do is replace it with a regulated 12V DC supply. They are also sometimes sold as being 12V LED power supplies, there is no difference its just a 12V DC supply.Some even look similar to these halogen ones, but will generally say LED on it:But yeah be careful with cheap chinese mains supplies, i seen them explode in person. So it is a good idea to earth the ground on the output and to keep it away from anything flammable like wood. The 12V LED bulbs (halogen replacement form factor) from china on the other hand are great. I have lots of them around the house and never had one fail, tho they do have bit of meh build quality and the color temperature can be slightly inacirate if you order the same bulb twice but don't come from the same batch.

author: nfmax
author_rank: Super Contributor
timestamp: October 24, 2018, 01:03:51 pm
content: Those 'electronic transformers' put out a square-ish wave of a few kHz frequency, often amplitude-modulated by (twice) the line frequency. Halogen bulbs don't care. Most LED bulbs do, since they either have ludicrously slow, cheap, rectifiers or filter networks that block it. You will need either a real iron-and-copper transformer, a 12VDC converter, or an 'electronic LED transformer' that works at 50/60Hz. If the latter, try it first with the bulbs you are going to use. Nothing else will ensure compatibility. The whole situation is a complete mess.And don't waste your time with LED bulbs using a capacitative dropper - the first fast transient spike on the mains will go straight through and blow them up. Been there, done that!