flickering LEDs

[Tonkabot]

I just mounted some 12V LED strips to my end effector, and tied them into the PEEK fan supply, because I thought it was on all the time when printing.

Funny thing, they flicker. This implies that the PEEK fan is either PWMed or turned on and off a lot.

Do I need to run another set of wires to power them?

They do light up the work really well, and I made a little holder for them using Spaceclaim - which seems way easier to learn than ProE or Inventor.
And there is a totally free version of spaceclaim called design spark.

[Jimustanguitar]

This is pretty normal. I don't have a technical explanation, but the LEDs are that way on most of the machines I've seen. My guess is that the ATX supply isn't as "quick" as the PID for the heaters and you're seeing that flutter.

Anybody rigged up a fix with a capacitor?

[add1ct3dd]

See my thread: http://forum.seemecnc.com/viewtopic.php?f=37&t=6924

Same issue & fix :]

[Tonkabot]

Okay, I followed the other thread. I thought that hooking into the PEEK fan would bypass the PWM or PID of the hotend.

Apparently you guys are saying that the PC ATX supply is just plan crappy on the 12V output. I'll throw a scope on to look at the signal and then see about a CAP or DC2DC converter or something.

Maybe there is a place for a supply optimized for 3D printers, with like 5v, 12v, and 24v or adjustable 12-24v in addition to the fixed 12. So it can supply the Bed extra power. With good (independant) regulation on all the voltages.

How much power is required for the bed, steppers, and each hot end?

[Eaglezsoar]

Okay, I followed the other thread. I thought that hooking into the PEEK fan would bypass the PWM or PID of the hotend.

Apparently you guys are saying that the PC ATX supply is just plan crappy on the 12V output. I'll throw a scope on to look at the signal and then see about a CAP or DC2DC converter or something.

Maybe there is a place for a supply optimized for 3D printers, with like 5v, 12v, and 24v or adjustable 12-24v in addition to the fixed 12. So it can supply the Bed extra power. With good (independant) regulation on all the voltages.

How much power is required for the bed, steppers, and each hot end?

http://forum.seemecnc.com/viewtopic.php?f=37&t=6924 has the component that is a constant current and voltage device which is a lot cheaper then new power supplies, etc.

[Tonkabot]

viewtopic.php?f=37&t=6924 has the component that is a constant current and voltage device which is a lot cheaper then new power supplies, etc.

I looked at that. It appears to be a 5A buck converter with settable output voltage and current.

So it would not be suitable to try to supply the bed. And probably not for hot-ends, either.

Also, The LEDs I am using want 12v, and work even better at 13.6v or whatever a car alternator is running at. If I were to try and put the dirty 12v (from the PC supply) I doubt I could get more than 11.5v out from that Ebay Buck converter. It would work fine for running 5V LEDs.
It is not labeled clearly, possibly it can put out higher voltage than input, but it doesn't look like it has the right components for a Buck-Boost or Sepic supply.

Something like this: http://www.amazon.com/DROK-1-2-30V-Volt ... pic+supply would work better if just used to drive my LEDs. It is a SEPIC and can set the output to lower OR higher than the input voltage.
It is only 2Amps however. But my 9 LEDs I currently have are going to be way below that in current.

Anyway, I was thinking about replacing the PC ATX supply completely with a unit that is designed for printers - namely fairly low current needed at 5v and high currents needed at 12v and/or 12v-24v. The problem is that PC supplies are cheap, and have the certification to run 'off-line'.

Maybe the thing to do is get a off-line brick that does 24v 30A or so, and run a couple DC to DC converters to get the 12V and 5V from that. That would/should provide much cleaner power, plus enough to run 24V to the Bed.

[Eaglezsoar]

viewtopic.php?f=37&t=6924 has the component that is a constant current and voltage device which is a lot cheaper then new power supplies, etc.

I looked at that. It appears to be a 5A buck converter with settable output voltage and current.

So it would not be suitable to try to supply the bed. And probably not for hot-ends, either.

Also, The LEDs I am using want 12v, and work even better at 13.6v or whatever a car alternator is running at. If I were to try and put the dirty 12v (from the PC supply) I doubt I could get more than 11.5v out from that Ebay Buck converter. It would work fine for running 5V LEDs.
It is not labeled clearly, possibly it can put out higher voltage than input, but it doesn't look like it has the right components for a Buck-Boost or Sepic supply.

Something like this: http://www.amazon.com/DROK-1-2-30V-Volt ... pic+supply would work better if just used to drive my LEDs. It is a SEPIC and can set the output to lower OR higher than the input voltage.
It is only 2Amps however. But my 9 LEDs I currently have are going to be way below that in current.

Anyway, I was thinking about replacing the PC ATX supply completely with a unit that is designed for printers - namely fairly low current needed at 5v and high currents needed at 12v and/or 12v-24v. The problem is that PC supplies are cheap, and have the certification to run 'off-line'.

Maybe the thing to do is get a off-line brick that does 24v 30A or so, and run a couple DC to DC converters to get the 12V and 5V from that. That would/should provide much cleaner power, plus enough to run 24V to the Bed.

It is designed to go between the leds and the power supplying them and only them.

[Tonkabot]

I put a scope on the peek fan earlier, and found the following:
12.1v peek fan only
11.7v head on %100
11.5v Bed on %100
11.1v Head and Bed both on %100

And then when the head and bed reach temp they switch off and on, so the voltage jumps between the above values rapidly.

I think I'd rather use a SEPIC type converter like the one I found, and then I can pick a voltage above the input, like 13v for my LEDs.

Are you running the converter you suggested with a 12v output? If it is a buck converter, it doesn't seem like it should be able to keep the voltage at 12v.

[Eaglezsoar]

I put a scope on the peek fan earlier, and found the following:
12.1v peek fan only
11.7v head on %100
11.5v Bed on %100
11.1v Head and Bed both on %100

And then when the head and bed reach temp they switch off and on, so the voltage jumps between the above values rapidly.

I think I'd rather use a SEPIC type converter like the one I found, and then I can pick a voltage above the input, like 13v for my LEDs.

Are you running the converter you suggested with a 12v output? If it is a buck converter, it doesn't seem like it should be able to keep the voltage at 12v.

Led devices are current sensitive devices most being at the 20 milliamp max range. Usually a resistor limits the current. If your leds are brighter running at automobile voltages that means that
a better resistor value needs to be selected to give the leds more current but not exceeding the led specifications. See below for the calculations.

20 mA is a good MAXIMUM current rating for general-purpose LEDs. LEDs designed for lighting applications have much higher maximum current ratings.

LEDs are current-driven components. This means that if you have a voltage source, such as a power supply or a battery, you need a resistor in series with the LED to limit the current. If you connect an LED directly to a 12V power adapter, a very high current will flow and the LED will glow very brightly... for a very short time!

When you have an LED and a resistor in series, connected to a voltage source, the LED will drop a certain voltage, called its forward voltage. For general purpose LEDs, this voltage varies from about 2V (for red LEDs) to about 4V (for some white LEDs). The remaining voltage is dropped across the resistor.

The voltage across the resistor, and its resistance, together determine the current that will flow in the series circuit. You can calculate the current using Ohm's Law: I = V / R where I is the current, in AMPS; V is the voltage ACROSS THE RESISTOR, in volts, and R is the resistor value, in ohms.

To calculate the right resistor value to use, you can rearrange that formula to R = V / I, where R is the resistance you should use, in ohms; V is the voltage across the resistor, in volts, and I is the desired current, in amps.

For example, if you have an LED with a forward voltage of 3.0V and a power supply of 12V, and you want to run the LED at 20 mA. The series resistor should be:
R = V / I
V = (12 - 3) = 9 (remember, V is the voltage ACROSS THE RESISTOR)
I = 0.02 (remember, I is in AMPS, not milliamps)
R = 9 / 0.02
= 450 ohms.

Point being that leds could care less what the voltage is, they care about how much current
flows through them. Voltage does matter however because an increase or decrease in voltage causes a corresponding rise and fall in the current.

I know that the device I talked about works and several users use them. It may not work for you and you should purchase whatever you know that will work.
Sharing each others ideas is part of what this Forum is about.

[Tonkabot]

Are you running the converter you suggested with a 12v output? If it is a buck converter, it doesn't seem like it should be able to keep the voltage at 12v.

Led devices are current sensitive devices most being at the 20 milliamp max range. Usually a resistor limits the current. If your leds are brighter running at automobile voltages that means that
a better resistor value needs to be selected to give the leds more current but not exceeding the led specifications. See below for the calculations.

[snip]
Point being that leds could care less what the voltage is, they care about how much current
flows through them. Voltage does matter however because an increase or decrease in voltage causes a corresponding rise and fall in the current.

I know that the device I talked about works and several users use them. It may not work for you and you should purchase whatever you know that will work.
Sharing each others ideas is part of what this Forum is about.

But you never answered the question: are you running that converter with a 12v output? Yes, if you are using it in current limiting mode, you would just crank the voltage and dial in the current to the desired brightness, but that only really should work up to some voltage lower than about 10.5v (looking at the data I got) for a Buck supply like the one you mention. So I guess the better question is what voltage your LEDs drop?

I am an EE so I understand ohms law and LEDs and voltage and current. The LEDs that I am using are for lighting and I am pretty sure they run a lot more than 20mA each.

Eaglezsoar, your forum name in bright yellow is not readable to me. The contrast between the yellow and white background on the 'silversomething' theme I have the forum set on is to little to be able to read clearly, in case you didn't know.

[Jimustanguitar]

Eaglezsoar, your forum name in bright yellow is not readable to me. The contrast between the yellow and white background on the 'silversomething' theme I have the forum set on is to little to be able to read clearly, in case you didn't know.

You must be viewing the forum's mobile site... Background is normally gray.

[Mac The Knife]

Eaglezsoar, your forum name in bright yellow is not readable to me. The contrast between the yellow and white background on the 'silversomething' theme I have the forum set on is to little to be able to read clearly, in case you didn't know.

You must be viewing the forum's mobile site... Background is normally gray.

switch your board preference to Artodia (black), Then the bright yellow lettering will be visable.

[Eaglezsoar]

Are you running the converter you suggested with a 12v output? If it is a buck converter, it doesn't seem like it should be able to keep the voltage at 12v.

Led devices are current sensitive devices most being at the 20 milliamp max range. Usually a resistor limits the current. If your leds are brighter running at automobile voltages that means that
a better resistor value needs to be selected to give the leds more current but not exceeding the led specifications. See below for the calculations.

[snip]
Point being that leds could care less what the voltage is, they care about how much current
flows through them. Voltage does matter however because an increase or decrease in voltage causes a corresponding rise and fall in the current.

I know that the device I talked about works and several users use them. It may not work for you and you should purchase whatever you know that will work.
Sharing each others ideas is part of what this Forum is about.

But you never answered the question: are you running that converter with a 12v output? Yes, if you are using it in current limiting mode, you would just crank the voltage and dial in the current to the desired brightness, but that only really should work up to some voltage lower than about 10.5v (looking at the data I got) for a Buck supply like the one you mention. So I guess the better question is what voltage your LEDs drop?

I am an EE so I understand ohms law and LEDs and voltage and current. The LEDs that I am using are for lighting and I am pretty sure they run a lot more than 20mA each.

Eaglezsoar, your forum name in bright yellow is not readable to me. The contrast between the yellow and white background on the 'silversomething' theme I have the forum set on is to little to be able to read clearly, in case you didn't know.

Yes I am running at the 12Volts and you are correct that I dialed in the current to the desired brightness, they are not as bright as they would be without the converter but they do not flicker.
If you are using leds designed for lighting you are going to be in the watts rating, not milliamps. Yes , the yellow on grey or white does not stand out but most would want that way then they don't have
to read my ramblings. Happy Holidays!

[jdurand]

Some lighting applications use regular LEDs (often T1-3/4 or 5mm) and some don't. Some have constant current chips in them, some just use resistors. We have a grow light over our fish tank that has a large number of standard LEDs in series/parallel and all run off one constant current power supply. It's happy from about 10-20VDC, brightness doesn't change.

The lighting dimmers we made for a certain Canadian circus drive the paste-down LED strips that have medium-range white LEDs in them. Each strip doesn't draw a lot but when you have a boat load of them our dimmer has to put out 40 Amps @ 24V.

For the application we're discussing, a simple & cheap thing would be to get a 12V to 24 or 36V boost converter and put tow or three 12V strips in series (red to black), this way the converter is always in a happy operating range.

[Tonkabot]

Some lighting applications use regular LEDs (often T1-3/4 or 5mm) and some don't. Some have constant current chips in them, some just use resistors. We have a grow light over our fish tank that has a large number of standard LEDs in series/parallel and all run off one constant current power supply. It's happy from about 10-20VDC, brightness doesn't change.

The lighting dimmers we made for a certain Canadian circus drive the paste-down LED strips that have medium-range white LEDs in them. Each strip doesn't draw a lot but when you have a boat load of them our dimmer has to put out 40 Amps @ 24V.

For the application we're discussing, a simple & cheap thing would be to get a 12V to 24 or 36V boost converter and put tow or three 12V strips in series (red to black), this way the converter is always in a happy operating range.

Even a 9v to 12V boost would probably work fine. Or about 12Vin and adjustable output will take the noisy 11v or so that we have and put out a solid 13.2v for my 12v strips, which are the cheap white medium-range ones your talking about. In case you can't find a SEPIC or Buck-Boost supply like I posted a link to above.

I have them in my trailer, they actually work really awesome there (trailer for the race car - I don't live in a trailer). However, beware of the pre-applied double stick adhesive. It really was more of a 'half-stick'. It was so bad that I actually soaked them in acetone to remove the crappy double stick so I could use a real 3M automotive double stick stuff to apply them to the ceiling ribs in the trailer.