Need help with LED's flickering on Malibu landscape lighting transformer

[diebog]

So I have some stairs going from garage to house (indoors) that I put those Malibu half brick stair lights in that used a 7wat T5 bulb. I wanted to change them to LED because they keep going out so easily and they take hardly any electricity to power. I chose to use THESE LED bulbs because they claim they work as replacements for Malibu lights and were a good deal.

I have 20 lights total on this 60 watt 12v AC Malibu transformer (ML60T) and these LED's flicker like a super fast strobe light. Almost like when a florescent light is going out. But when I put a regular 7w bulb back in, there is no flicker in that one blub. My guess is the alternating current is either back-feeding or something causing them to flicker.

Did some research and found others have similar issues but couldn't find a direct fix. Some suggested a Full Wave Bridge Rectifier, to turn the 12VAC into 12VDC but I have no idea what to source for my needs. One sugg was THIS ONE. But is that all I need to fix the flickering?

Note: I would also like a way to dim the LED's all at once. Like a dimmer switch that I could wire after the transformer. Wife says they are still to bright

Know I know a little bit about electronics, but no where near enough to design whats needed. I'm able to solder, test stuff, replace electronic parts, worked with SMT parts a little, but that's about it. If I was told what parts to buy and had a simple schematic, I could put it together.

So is there a module out there that would do exactly what I am trying to do? (eliminate flicker and add dimmer) If not, is there anyone here that could help me out with the parts and what not to build whats needed? I sure would appreciate it!

 

[G_P]

The LED's are flickering 60 times per second due to the AC.

That rectifier should solve your flickering issue. As for dimming them you might be able to simply lower the voltage to them to dim them. But if the bulbs themselves have a driver built into them they may not work on a lower voltage.

 

[dutchgray]

If you want to dim them its best to go with an LED suitable dimmer and a dedicated LED driver instead of the transformer you have.

 

[hackwelder]

A full wave bridge rectifier will change the frequency of the flicker to 120 times per second, to eliminate it entirely you would need a capacitor too, there are lots of plans for DIY power supplies out on the web....worth building one if you want the experience and Radio Shack carries the required parts but probably not much cheaper than buying a LED power supply, especially if you want dimming capability.

 

[cybrdyke]

Did you say your Malibu transformer put out 12v AC? I thought they were all putting out 12v DC. That's why they're so safe, you can touch the wires even when hot, you get voltage drop, etc, etc, etc. You might wanna double check that.
CD

 

[G_P]

Most landscape lighting transformers that are made to run incandescent bulbs output AC voltage. No need for the added expense to convert it to DC since an incandescent bulb does not care if it is fed AC or DC.

 

[dutchgray]

Most landscape lighting transformers that are made to run incandescent bulbs output AC voltage. No need for the added expense to convert it to DC since an incandescent bulb does not care if it is fed AC or DC.

I believe incandescent bulbs last longer on AC power.

 

[diebog]

A full wave bridge rectifier will change the frequency of the flicker to 120 times per second, to eliminate it entirely you would need a capacitor too, there are lots of plans for DIY power supplies out on the web....worth building one if you want the experience and Radio Shack carries the required parts but probably not much cheaper than buying a LED power supply, especially if you want dimming capability.

Ya I found this same schematic and was going to make one with some 1N504 or 1N506 diodes I have. Guess it doesn't really matter which ones I use. I was then going to pit a capacitor on the two sides that become DC but dot know what size to use. I have a ton of capacitors I have took of old boards, just don't know what the min is on something like this.

As far as dimming goes, could I just wire in a resistor after the rectifier/capacitor to dim it some. I don't really need a full sweep type dimmer, just want to take some of that super brightness away. But again figuring out what size resistor to use here is difficult. Each bulb had 5 5050 LED's so I guess it is just about doing the math on it.

 

[diebog]

Did you say your Malibu transformer put out 12v AC? I thought they were all putting out 12v DC. That's why they're so safe, you can touch the wires even when hot, you get voltage drop, etc, etc, etc. You might wanna double check that.
CD

I thought this exact same thing. I was touching the output wires testing the voltage because I could of swore it was 12v dc. My Fluke showed Mv not V when taking a reading. So I tried a few other DMM like a Matco, and another Fluke and same thing. I decided to switch it to AC and it showed around 12v. I thought that cant be, but upon doing some google searching, I found it was indeed AC. The transformer itself doesn't say AC or DC, it just says 12v out.

So I guess 12v AC is to low to feel anything.