Power cycle?

[Richie89]

Does anyone else called it power cycle? because duty cycle just for some reason sounds weird and funny.

Anyways this post is because I want some more opinions, a while back I build a Pltb450b 1.6 watt apx. I am only running a standard c6 NON copper heat sink with no thermal compound and the 1800ma Driver which in reality gets me a very short Cycle. I usually only run it about 20-30 sec on 60-100 sec off - because I decided to take the cheap way out and not run copper except on the module itself thanks to DTR
So should I keep it at this time frame or can I push 45 sec? Thanks everyone.

 

[Astralist]

Determining the duty cycle (AFAIK it's called "duty" because of ON time or simply the % of time of which the system turned ON) is quite tricky, there is many factor could determine the duty cycle.

First thing first, you can prolong the ON time by adding thermal compound, even the cheapest one could really improve the duty cycle.
The environment temperature could be a factor as well.

In conclusion (in a quite naive thinking), you can turn it on as long as it doesn't get hot. Diode working in hot temperature with high forward current can shorten it's life, so i guess you know what to do

 

[ElectricPlasma]

Assuming the material is aluminum I don't think it really matters if it were copper, what matters more is getting that heat away from the sink and into the air, which is probably pretty hard to do if it's inside the flashlight body. I think as long as you're not pushing it so far that it's too hot to touch you can squeeze in a bit more run time.

 

[GSS]

I have the same diode at the same 1.8A in a aluminum sinked 501b host.
Iv'e pushed it a few time to 60 seconds with no issue's. If i'm correct the C6 sink is a bit smaller? With the lack of thermal compound I wouldn't know, but 45 seconds sounds very doable. You do have the copper module and aluminum is not that much below as far as sinking..I think that C6 is fine and you can easily add compound. You can also feel the heat better in the C6 compared to other bigger hosts.
By the way isn't that PLTB450 a sweet diode, spec wise

 

[Astralist]

Without thermal compound, it could be problematic because the heat transfer from the module to the host will be slow, we can feel that the host surface still warm but in fact the inside could be hot as hell.

 

[GSS]

Without thermal compound, it could be problematic because the heat transfer from the module to the host will be slow, we can feel that the host surface still warm but in fact the inside could be hot as hell.

Yup, just might not be worth pushing it without compound. Even with my IR gun its so tricky to find the right hot spot and going by feel just isn't worth it.

 

[Cyparagon]

Power cycle denotes a brief OFF and then ON. AKA "have you tried turning it off, and on again?" You're going to confuse a lot of people calling it power cycle.

Duty cycle is the correct term, although it is usually in relation to pulse-width modulation (PWM), where it is given as a percentage.

 

[paul1598419]

Assuming the material is aluminum I don't think it really matters if it were copper, what matters more is getting that heat away from the sink and into the air, which is probably pretty hard to do if it's inside the flashlight body. I think as long as you're not pushing it so far that it's too hot to touch you can squeeze in a bit more run time.

Actually, the material you are using for the heat sink doesn't make it more or less better as far as moving heat away from the diode and into another place. In other words, aluminum is not better at moving heat to the air than copper is. It is the thermal conductivity of the material that makes it a better heat sink and, therefore, can move heat into the air. For this reason, copper is by far a better heat sink than aluminum in a volume:volume ratio. Because copper is so soft, it is difficult to make fins out of it that won't be damaged by impacts, so many copper heat sinks are pressed into aluminum ones as aluminum makes good fins.

 

[Richie89]

Determining the duty cycle (AFAIK it's called "duty" because of ON time or simply the % of time of which the system turned ON) is quite tricky, there is many factor could determine the duty cycle.

First thing first, you can prolong the ON time by adding thermal compound, even the cheapest one could really improve the duty cycle.
The environment temperature could be a factor as well.

In conclusion (in a quite naive thinking), you can turn it on as long as it doesn't get hot. Diode working in hot temperature with high forward current can shorten it's life, so i guess you know what to do

Yeah it actually doesn't get that warm mostly because I usually keep it pretty cool in my house. I may take it apart and get some compound in there between the module and heat sink.

Assuming the material is aluminum I don't think it really matters if it were copper, what matters more is getting that heat away from the sink and into the air, which is probably pretty hard to do if it's inside the flashlight body. I think as long as you're not pushing it so far that it's too hot to touch you can squeeze in a bit more run time.

Hey there EP! Long time no talk
Yeah that's the bad thing about those c6s when going past a watt they heat up quickly. I have some questions about some of the hosts you have because I soon want to build one into a much larger and thermally conductive host to get a feed minutes. I'll PM you soon.

I have the same diode at the same 1.8A in a aluminum sinked 501b host.
Iv'e pushed it a few time to 60 seconds with no issue's. If i'm correct the C6 sink is a bit smaller? With the lack of thermal compound I wouldn't know, but 45 seconds sounds very doable. You do have the copper module and aluminum is not that much below as far as sinking..I think that C6 is fine and you can easily add compound. You can also feel the heat better in the C6 compared to other bigger hosts.
By the way isn't that PLTB450 a sweet diode, spec wise

I think I may do that, I'll order some Thermal compound since I'm gonna need it soon. Hah yes that Pltb450b is an awesome diode. Lots of power fairly cheap price tag

Power cycle denotes a brief OFF and then ON. AKA "have you tried turning it off, and on again?" You're going to confuse a lot of people calling it power cycle.

Duty cycle is the correct term, although it is usually in relation to pulse-width modulation (PWM), where it is given as a percentage.

I apologize, I do need to just say Duty cycle since that exactly what it's called, it is probably just because I got some slightly immature friends that laugh when I say "Duty Cycle"

 

[Lifetime17]

Hi Richie,
as folks said getting the heat to transfer to the sink then cooled by air you will need something like this pic . In Al or CU or even a AL sink with a CU core pressed in. I love the PLTB450B diode and built many as they are one of my favorites and they do get hot set to 1.8A

Rich

 

[Benm]

Duty cycle is indeed the correct engineering term. Often it's applied to more rapid signals like PWM modulation, but it can also be used for far slower systems like chemical reactors that can be used for 25% of time and then needing 75% of time to cool down or otherwise recover.

For lasers with inadequate cooling duty cycle means something similar, though it should be specified what the timeframe actually is: if you claim 25% maximum duty cycle for a pointer, i could interpret that as 1 day on, 3 days off, while a second (or minute) might be more likely. With semiconductors even shorter intervals can be in place, like a diode being able to handle 100 amps at 10% duty cycle, assuming operation at a megahertz in a switchmode power supply system. Running that diode for 1 second at 100 amps will probably destroy it, regardless if you wait 9 seconds for it to cool down after or not.

And a power cycle is, as mentioned, something completely different: that is how many times you can turn something on and off before it fails. This could apply to something like a lightbulb that has 2000 hours of life, and 10.000 power cycles. That would mean the lamp would last a couple of months if you just turned it on and off once a day, but would be dead if you kept flipping the power switch on and off for a few hours... which might be a realistic assuption on a hot running tungsten lamp

 

[GSS]

Richie, I would give Lifetime a PM..You will be surprised just how little he wants for a complete just 2 wire to wire plug and plays..5 minutes of work from you for worry free duty cycle..
He's showing the SkyRay's with a side clicky which I prefer but he probably has some 501b's ready to go also..
Lot's of great host builders here and i'm not being bias but Lifetime has a whole stack of them ready to go..

 

[Richie89]

Hi Richie,
as folks said getting the heat to transfer to the sink then cooled by air you will need something like this pic . In Al or CU or even a AL sink with a CU core pressed in. I love the PLTB450B diode and built many as they are one of my favorites and they do get hot set to 1.8A

Rich

Hey Rich, I agree. I love the pltb450b because of its relatively cheap price tag and pretty decent beam Divergence, well at least compared to my M140 build. GSS has definitely giving me some good advice to get ahold of you to build me a nice large sink since I know you can do some longer C6 style heat sinks. I like to use those because I have a lot of them laying around and they're readily available. I may have you make me one soon or just a plug and play type host. Thanks again.

Richie, I would give Lifetime a PM..You will be surprised just how little he wants for a complete just 2 wire to wire plug and plays..5 minutes of work from you for worry free duty cycle..
He's showing the SkyRay's with a side clicky which I prefer but he probably has some 501b's ready to go also..
Lot's of great host builders here and i'm not being bias but Lifetime has a whole stack of them ready to go..

You're right, I'm definitely gonna have to Have him do something soon because I can't take these 20-30 sec duty cycles, they're making me crazy!! Haha
I find myself making it cooler than normal in my house just to squeeze an extra 5-10 seconds out of them I appreciate the advice.

 

[GSS]

You can always play with it in the freezer or stick a fan on a head band:thinking:
Keeping your house cold just to play with a laser:beer:

 

[Richie89]

You can always play with it in the freezer or stick a fan on a head band:thinking:
Keeping your house cold just to play with a laser:beer:

Lmao! Yeah my electric bill is probably an additional 20 bucks for nothing. I've actually got a goal that I have been wanting to achieve for almost a year, and that is to eventually have a 2-3 watt 445-455nm laser with an continuous Duty cycle. I know I'll have to shell out some Benjamins. At least 300, but it would be awesome since I know a lot of y'all have at least one probably.

 

[paul1598419]

Richie, I would give Lifetime a PM..You will be surprised just how little he wants for a complete just 2 wire to wire plug and plays..5 minutes of work from you for worry free duty cycle..
He's showing the SkyRay's with a side clicky which I prefer but he probably has some 501b's ready to go also..
Lot's of great host builders here and i'm not being bias but Lifetime has a whole stack of them ready to go..

I still have a couple of 501b hosts in my stock. I like to use them for builds at or below 500 mW. They are a great cheap alternative to a completely designed and built host.