Mains bed pwm frequency/flickering lights.

deckingman

@DIY-O-Sphere said in Mains bed pwm frequency/flickering lights.:

@Surgikill said in Mains bed pwm frequency/flickering lights.:

I think once I insulate the bed

Depends on your bed. Mine is isulated and 8mm thick. There I could set the fequenz even further down because the thermal inertia is high. 10 means 10 times per second, if I remember correctly this was once the default setting in the FW. So it should work.....

Indeed. 10Hz always used to be the default frequency for bed heaters and that's what I still use, with a bed configuration similar to yours (8mm, insulated etc).

Surgikill

@hackinistrator I can try it, would just rather fix the problem at the source.

@zapta The bed is 489x355, with build area being around 320x320. I'd have to buy a new bed heater in order to run it, or get a high voltage DC power supply. At 24V the bed would only be producing about 40 watts, which isn't enough. 64V would put me around 270 watts, which might work, but would be slow as hell.

@DIY-O-Sphere My bed is only about 3mm thick, so not a lot of thermal mass, but heats up quickly.

zapta

@Surgikill said in Mains bed pwm frequency/flickering lights.:

@hackinistrator I can try it, would just rather fix the problem at the source.

I think this means fixing the house's wiring.

Surgikill

@zapta Unfortunately you're right. Also unfortunately I bought it a year ago and don't plan to live in it for more than 5 years, so I'm just trying to find the best bandaid I can.

mrehorstdmd

I see similar light flickering when the bed heater kicks on and off, especially on dimmed LED bulbs which seem especially sensitive to the line voltage. I've seen similar flicker from fluorescent lamps.

An 800W heater takes almost 7A from a 117VAC line. The printer operates in parallel with the lights. If there's only an Ohm between the load (printer and light) and the "source" (breaker panel) that will cause a 7V drop in the line voltage when the heater switches on, hence the flicker. It doesn't matter if you have a zero crossing SSR or not, the voltage will drop and the lights will flicker.

The solution is to either turn off the lights or plug the printer into a different power circuit.

zapta

@Surgikill said in Mains bed pwm frequency/flickering lights.:

I'm just trying to find the best bandaid I can.

Ny bed is 300x300x6mm, uses 380W 24V, and it doesn't feel too slow considering the time it takes the extruder to heat and the overall print time.

In a sense, I prefer slower heating to avoid distorting the plate (Just a guts feeling, not scientifically based).

zapta

@mrehorstdmd said in Mains bed pwm frequency/flickering lights.:

LED bulbs which seem especially sensitive to the line voltage

I always assumed that they have a smart constant current driver but maybe it's not the case, or maybe some do and some don't.

hackinistrator

@zapta he's using mains powered strips , those usually contain a bridge rectifier and bunch of resistors .
that's why i think the best solution is to just add a big capacitor after the rectifier .

Surgikill

@hackinistrator It still won't fix the other lights in the room, unfortunately.

@mrehorstdmd That's why I was trying to increase PWM if possible, then the lights would just dim every 10-15 seconds instead of flickering constantly.

hackinistrator

@Surgikill you need to reduce pwm freq if you want them flicker once in 15sec . i'm not sure whats the minimum pwm freq , you can try Q value of 0.1 or lower (for older firmware that's F0.1 in M307) . this will also cause fluctuation in your bed temp ,it depends how thick is your plate .

Phaedrux

I had flickering halogen pot lights at one point. I set the frequency to 1hz and it went away.

T3P3Tony

Might be worth setting them to bang bang mode in that case...

droftarts

@hackinistrator said in Mains bed pwm frequency/flickering lights.:

I'm not sure whats the minimum pwm freq , you can try Q value of 0.1 or lower

I did a quick test, as I'd suggested Q0.1 in a previous thread, but minimum PWM appears to be 1Hz:

M950 H0
Heater 0 pin bedheat frequency 250Hz, sensor 0
M950 H0 Q1
M950 H0
Heater 0 pin bedheat frequency 1Hz, sensor 0
M950 H0 Q0.1
M950 H0
Heater 0 pin bedheat frequency 1Hz, sensor 0
M950 H0 Q0
M950 H0
Heater 0 pin bedheat frequency 1Hz, sensor 0
M950 H0 Q10
M950 H0
Heater 0 pin bedheat frequency 10Hz, sensor 0

Ian

mendenmh

@Surgikill I should note that, in reply to people who think an 800 watt bed won't flicker your lights, the 200 watt bed on my printer was plenty.

Note that LED lighting is very sensitive to voltage, and I had somehow allowed the PWM to fall back to 10 Hz at some point. A 10 Hz modulation of light seems to be right at the very peak of my eye's sensitivity. It wasn't visible on incandescent lights or CFLs. It may be a consequence of my buying largely very cheap LED lights from Home Depot, too. My better-grade bulbs didn't flicker visibly.

I doubt my line voltage was changing by more than a fraction of a percent but it was terribly annoying. Moving the PWM back to 60 Hz fixed it. It had two effects: first, most of the modulated energy was then being provided by the filter capacitors on the power supply, so very little of the fluctuation was being sourced by the power lines; second, my eye isn't very sensitive to 60 Hz modulation in the first place.

FWIW

fcwilt

You've got a house wiring problem.

I see two solutions short of trying to get by with a DC powered bed heater.

run another line from the load center to a dedicated outlet for your printer
get a suitably rated dual-conversion UPS to power your printer

Frederick

tenaja

Don't forget ohms law...a couple guys have alluded to it, but you need to embrace it.

jens55

@fcwilt said in Mains bed pwm frequency/flickering lights.:

You've got a house wiring problem.

I see two solutions short of trying to get by with a DC powered bed heater.

run another line from the load center to a dedicated outlet for your printer

get a suitably rated dual-conversion UPS to power your printer

Frederick

Those are the two choices that make sense. Note the "dual-conversion" bit. A regular UPS is not likely to fix anything and if in fact it reacts to the brown outs, it will likely kill the UPS in no time flat (of course depending on the quality of the UPS)

Surgikill

@tenaja Ohm's law is what is killing me. That, and the idiots that wired this house.

jens55

While this may sound stupid, if you want to go cheap and cheerful, get a 12 ga extension cord (HD outdoor type used by contractors) and run it from the FIRST outlet on that circuit directly to the printer.
Might want to try the printer directly on that FIRST outlet to see if it makes sense buying a long extension cord.
That way you will bypass all the joints that are made with wiring nuts for each and every outlet that is wired in a long string.

Surgikill

@jens55 I can try that, but it's going to be going all the way down my hallway. I already have one extension cord in the hallway, and it's to feed my server from a different circuit. It's not too bad if I keep the overhead lights off.