# Electrical – LED Flickering on Mains

ledled stripled-drivermains

I've just bought 10m of 220VAC LED Strip yesterday just to found out that it flicker so bad on mains. My country is using the 220V 50Hz as their mains.
Anyone can help me on a way to reduce the flicker? What I'm thinking is adding a 0.47uF 400V caps before the LED.. Is it a good idea? Or are there any way to lessen the effect of flicker? I don't need it to be completely gone (as it is pretty much impossible)

I don't want to throw this strip and buy 12v or 24v ones because I've already bought 10m of em and the store doesn't have a return policy.

EDIT: Since many people asked for a schematics.. I don't have any, but I forgot to say that it is indeed an SMD 5050 LED, will try to find any schematics for that. And here's a pic to it http://imgur.com/16Yg96a
For anyone who's wondering what is written on the R, it is 391. Sorry for my camera.

## Rev x

**From reviewing your Photo, I misread 60-D-16R as 16Ω but in fact 391 is correct and \$16E\$ is upside down was my misteak

## Plan C

Assuming 33 mA, 390Ω, Vtot = 2.8V*4 + 390Ω*0.033A = 24.07V ...*0.033A= =0.8W

## Old info from insufficient data and poor description for historical ruminance

Plan B ( based on poor specs) - Measuring the Photo the 4LED + 16R , pitch is 60mm and total power @14V= 2.367W/m - Thus 24W per 10 m minimum. cooler.
- Suggested Supply Tolerance 14V+/-0.2V @ 2A min pref 3A - 12V will work but dimmer.

In order to smoothen the flicker let's do some calculations.

• First you need a bridge rectifier to make rectified AC into DC.
• Second , the decay time between 10ms pulses needs to attenuate 100Hz by at least 20dB or 10:1 in current to be significantly attenuate flicker.

• if they did something like use 2 diodes to run 1 string in + and another on - then the flicker rate would be really bad at 50Hz.

So what value C is needed and at what cost?

• I know that 10% ripple uses RC=8t and R=10~15 Ohms (approx) per 65mW~100mW white LED.
• For an RMS voltage of 220V , let's assume there are 330 LED's split into 5 strings of 66 in series or 5P66S with a Vf of 66*3V=198Vdc
• the stripleds resistance when above 198V becomes 166*15R/5 ~500 Ohms
• thus C=80ms/500 Ohms=160uF !! at >400V rating with a series drop resistor of 20V/(20mA*5P)=200 Ohms @ 2W

You can substitute your values and see if you want to retire it or rewire it with a bridge , **cap, power resistor . have fun and get extra R in case it is too bright or too hot. The resistor must be flame proof and rated for line voltage.