LED - Transformer

Charl_Stanhope

Charl_Stanhope

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I have received three of these
picture.php

from a guy that took a big led setup out of a shop. Ihave hooked up
8 x 3w LED chips to it. The problem I have is that the leds are on, not
as bright as they should be and they seem to be flickering really fast.
Any ideas of what the problem is. I have tested my soldering and all the leds seems
to be soldered corrctly. These are conected in series. positve to negative.

The details of the transformer :

50VA . 230 -12v L/VOLT XMER
input is 0-230V
output is 0-12V and the transformer is fused.

any ideas for the electrical gurus ? :)
 
Charl_Stanhope said:
The problem I have is that the leds are on, not as bright as they should be and they seem to be flickering really fast.
Click to expand...

How were the LEDs connected previously and to what power supply such that they are not as bright?

Looks like you have a 12V low voltage lighting transformer there. Connecting it to the LEDs will invariably cause flicker because the LEDs will receive 12v 50hz AC and 50hz is what is causing the flicker you see
 
Thanx for the replies @butcherman and @Pri$m . Sorry I am only repying now.


butcherman said:
What amps is the transformer putting out?
Click to expand...
I havent tested yet to be honest. I will do a test when I get home tomorrow.


butcherman said:
What is the forward voltage and amp rating of the leds? Are they wired up in series?
Click to expand...

  • Forward voltage: 3.7V @700mA
  • Lumens: 180-200
  • Max. current: 700mA
These leds are wired up in series

Pri$m said:
How were the LEDs connected previously and to what power supply such that they are not as bright?

These are new leds I am using. I am currently running a few on my setup and they are so much brighter than these. Thats how I know that they are not as bright as they should be. Th led was build by an electrician.

Looks like you have a 12V low voltage lighting transformer there. Connecting it to the LEDs will invariably cause flicker because the LEDs will receive 12v 50hz AC and 50hz is what is causing the flicker you see
Click to expand...

What is the correct transformer to connect to these leds?
 
Last edited by a moderator:
LEDS run on constant current so it will all depend on the current output of the transformer.
 
Charl_Stanhope said:
What is the correct transformer to connect to these leds?
Click to expand...

Those LEDs you have should not be run off of a transformer as such (I'm guessing they are individual LED's?). They require a driver instead. The driver will supply the necessary voltage and current to the LEDs and dependent on the driver, how many LEDs in series.

The down-lighter replacement LED globes that are available have the necessary drive electronics within them to run off a transformer as you have.

If you try for example 3 or 4 LED's in series off that transformer they will run a great deal brighter but then you run the risk of burning them up as that transformer is capable of outputting about 4 amps at 12V. Your LED's are only designed for 700mA or 0.7A. They are a Current driven device and not a Voltage driven device and hence the critical variable is the current
 
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