Phase shift mains AC to de-flicker LEDs

[Zero999]

Oh, I also forgot to say:

The metal circuit board must be earthed for safety's sake. It's also quite likely they don't meet the bare minimum safety standards as they will lack sufficient insulation between the live parts and earth. If you mush use them, then I repeat, ensure the aluminium board is properly grounded!

I know this, which is why the heatsink IS already earthed. And not only that, the COB is in a plastic/glass lamp housing (with vent holes for airflow), so the heatsink can't even be touched unless you poke throuh the holes with a screwdriver.

Good, but that might not be enough.

The PCB probably doesn't meet the necessary requirements of creepage and clearances. Earthing shouldn't actually be required for safety. It's there in case the insulation fails. The insulation should be robust enough to withstand high voltage transient spikes due to lightning.
https://www.smps.us/pcbtracespacing.html

Poor insulation also increases the risk of fire. Is the housing flame retardant? I hope so.

[Circlotron]

Possibly the simplest and most effective, yet hopelessly too expensive method would be to have after the input bridge rectifier a choke input filter and then a big electro. If the choke is big enough the dc voltage will be 90% of the rms voltage or about 63% of the peak AC voltage. The led driver might be perfectly happy running continuously on this lower voltage. Added bonus is the choke (again, if big enough) would protect the circuit from mains borne transients and spikes. But like I said, unlikely to be cost effective. You could of course have an external bridge, choke and electro big enough to power a large number of lamps. That might change the cost effectiveness somewhat, especially if it contributed to longer lamp life because of lower voltage and no mains nasties.

Edit -> of course, at switch on the LC output might resonate up to double voltage for a moment...

[Zero999]

Possibly the simplest and most effective, yet hopelessly too expensive method would be to have after the input bridge rectifier a choke input filter and then a big electro. If the choke is big enough the dc voltage will be 90% of the rms voltage or about 63% of the peak AC voltage. The led driver might be perfectly happy running continuously on this lower voltage. Added bonus is the choke (again, if big enough) would protect the circuit from mains borne transients and spikes. But like I said, unlikely to be cost effective. You could of course have an external bridge, choke and electro big enough to power a large number of lamps. That might change the cost effectiveness somewhat, especially if it contributed to longer lamp life because of lower voltage and no mains nasties.

Edit -> of course, at switch on the LC output might resonate up to double voltage for a moment...

Perhaps a fluorescent ballast would do the trick? If you're lucky you can quite often get them for free from the tip. They're currently throwing lots of them away where I work, as they upgrading the lighting to LED, but I have no use for them..

[Circlotron]

^^ I know that mercury arc ballasts have a gapped core, so they will tolerate DC. I expect that fluoro ballasts are the same. Good suggestion! 

[Lupin III.]

I've attached a very simplified LTSPICE model.

Took some convincing to get LTSPICE to model this without getting stuck in the simulation. It really doesn't like the mains source to be connected via a capacitor only. A few 1Meg resistors to connect "floating" parts of the circuit did the trick. I also replaced the Zeners by a voltage controlled switch (controlled by the rectified mains) and another voltage source to simulate the forward voltage of the LEDs. Makes everything very adjustable to fit reality.
The output power drops quite a lot with the phase shift. On the other hand it doesn't really matter that much if the LEDs run at half the power considering how bright they are. If I find some inductor to shift a second LED the other way a little bit, I got the same output power with less flicker and longer LED life.

Connect a large capacitor in parallel with the bridge rectifier, then connect another capacitor in series with the AC input to limit the current.

That's another nice idea. Now that I got LTSPICE running I'll see what approximate component should be.

To those still saying "it's not worth it" or "just get proper LEDs". The LEDs are totally fine for general lighting use, even with the flicker. This is a project to hack something, to try things out and learn something. I fully intend to use components from parts bin or old PCBs, unless they'd cost me less than a Euro per LED. If I can't do it that way, so be it.

Oh, I also forgot to say:

The metal circuit board must be earthed for safety's sake. It's also quite likely they don't meet the bare minimum safety standards as they will lack sufficient insulation between the live parts and earth. If you mush use them, then I repeat, ensure the aluminium board is properly grounded!

I know this, which is why the heatsink IS already earthed. And not only that, the COB is in a plastic/glass lamp housing (with vent holes for airflow), so the heatsink can't even be touched unless you poke throuh the holes with a screwdriver.

Good, but that might not be enough.

The PCB probably doesn't meet the necessary requirements of creepage and clearances. Earthing shouldn't actually be required for safety. It's there in case the insulation fails. The insulation should be robust enough to withstand high voltage transient spikes due to lightning.
https://www.smps.us/pcbtracespacing.html

Poor insulation also increases the risk of fire. Is the housing flame retardant? I hope so.

All three phases to the home are equipped with surge protectors. There are RCDs on all circuits. The lamp is screwed to a concrete ceiling, the room is pretty much occupied all the time when the light is on.
But you gave me an idea. Building a 3-phase lamp! No flicker anymore! I'd just need to run a few additional wires from the outlets. The only problem: I don't need a sun in my workshop.

[Zero999]

If you have a three phase power supply, then the obvious solution is to put each LED lamp on a different phase. This is often done with old fluorescent and discharge lamps in large offices and factories. The lamps themselves will still flicker of course, but the light in the room not so much.

If you want to hack, then how about making your own LED lamp driver?

[Poe]

I simply increased the flicker frequency by adding additional off time and compensated by increasing the current during the on-times.

So instead of receiving a constant ~13W for ~6ms, then off for ~2ms near zero-cross (75%DC @120Hz)...

I drive it with ~20W for 2ms after Vin >30V, then off for 2ms near Vpk, then repeat until under 30V.  It's basically off for 50% of the time with a frequency of 240Hz. 

Power is about the same.  Largely eliminated the visuals by just adding a few passives to the existing drive circuit.