The Attiny25 has a built in temperature sensor that Bistro uses. Attiny25 also has more “room” for programming firmware. Attiny13 does not have those things.
But Attiny13 is more stable, is not so fiddly when you want to add a lighted tailcap or so.
@CRX I’m sciencing and you can do nothing to stop me!!! 
@ treellama @Henk4U2 The board that I have is this https://www.aliexpress.com/item/32831478212.html?spm=a2g0s.9042311.0.0.42174c4dhoNOZJ
(I don’t know if it’s allowed to post a link from a page so if not,please tell me if I need to remove it)
It’s a A6 driver from what I read,but it’s also a 17DD driver.Does it have a temperature sensor or not?Also for future reference,is it better if a driver has an onboard sensor,or is a NTC type like the LB-D4 sensor better?I’ve read somewhere that the Astrolux MF-01 mini has a problem with the onboard sensor,so it needs a cooling spacer in order to get better readings.What is your driver choice for a single cell light,with moonlight,40-60% med and accurate temp control?(If allowed please leave a link so I can read about it and order it)
Last question and I won’t bug you any further,the A6 driver is a 4A-6A current driver.Does that mean that this is the maximum it can deliver,or that it can’t go lower?
Thank you for your time guys,I’m learning a lot!!!
That one does not have a temperature sensor or thermal regulation. But, even on the ones that do that I have used (Bistro, Crescendo) it isn’t great. It will keep it from overheating, but it will not regulate it perfectly to the temperature you pick. So it will ramp up and down periodically instead of finding the sweet spot and staying there.
The LD B4 might do better, I haven’t used one. H17F might do better as well, haven’t used that either.
The A6 can deliver more than 4-6A with a high output battery / bypassed spring, and it can go much lower. There is a 350 mA constant current driver on there for the low modes, which it can PWM to get a nice moonlight. It’s a great choice if you have an LED that can be direct-driven. Just have to turn it off manually if it gets too hot.
What’s in a name. The A6 driver is a 17DD driver. Diameter=17mm DD=direct drive=FET.
So this ought to be okay. The enlargement is a bit blurry, so I can’t tell if it has a bleeder.
But if you want to add a lighted tailcap later on, a bleeder is quite simple added to the driver.
There is a potential issue that treellama has pointed out.
The Bistro driver has a temperature sensor, but it responds to the driver temperature.
That is better than nothing, but monitoring the Led-PCB for temperature would be better.
Be aware, the driver you asked about goes by many names. But Bistro is not one of them.
@treellama I see,so it’s more of a guess of what the temperature is on the actual LED,depending on what the driver and the body temperature is.I might have to check the LB-D4 because it’s easier shipping it.The H17F is only available through the US from what I’ve checked.Thank you for the information!
@Henk4U2 I’m getting to know the different names and it’s kind of hard,that’s why I got confused.So I should get one of those drivers and set the limit according to what’s comfortable within the range.That’s much clearer to me,thank you!!
Here, in case it’s of interest, is a way to spot weld a thermal sensor to a LED PCB:
The H17F,aka Dr Jones 17mm driver:
http://www.mtnelectronics.com/index.php?route=product/product&path=67_117&product_id=659
Very recently I've built a triple LED S2+ using this driver in a very well made copper pill from forum member Hoop.
This was my first full custom build.
So far the driver and firmware have performed well.
The copper pill is essential for conducting/transferring heat to the S2+ aluminum body.The stock brass pill is not nearly as good transferring the heat.
I use a thin wire sensor attached to the body to test temperatures.
A Sony VCT6 18650 is probably one of the best cells for this 5A driver and the 3 LEDs
Both springs are bypassed.
I'll be trying a few different thermal pastes as well as a 0.5mm fujipoly thermal pad between the 20mm Noctigon mcpcb and the copper pill.
I'll also put some 2019 MX4 on the pill threads
I'm still in the process of learning the H17F firmware.
A 2nd H17F should arrive today.
@Hank It can only be spot welded?What about regular solder?Is the spot welding process more heat resistant?
@Whatsthepoint Do you have any measurements for output approximately?What LEDs did you use?
I have no lumen measurement device but may add to the 'to do' list.
The sphere looks simple enough to make but without everyone using the same exact sphere and placing the meter ring in the same exact spot on the sphere results will not be comparable.Probable the Lux meter used should also be the same.
How can we compare measurements if our measuring devices have no required specs?
Right now I have the CREE XP-L High-Intensity V2 1A 6500k-7000k LEDs on NOCTIGON 3XP MCPCB in a red S2+ host that's CW but not overly blue tinted.
I can only visually guesstimate/compare brightness to a single SST40 with 5A convoy driver and a single XML2 1A 8*7135.
They all have SS 30Q in them right now.
I also have a triple XP-G3 X5 3C 5000k on MTN 3XP MCPCB,triple Samsung LH351D 5000k on MTN MCPCB and a triple CREE XP-L High-Intensity V3 1B 6000k-6500k LEDs on NOCTIGON 3XP MCPCB waiting to get put in hosts.
The S2+ with SST40 is extremely bright on highest setting but the triple XPL-Hi on turbo with the Dr Jones driver is a blinding fire stick that illuminates my master bedroom as if it was daylight at noon.
I like these small lights.Maybe build an S2+ in every color and maybe an S21A quad.
I’m definitely with you on that,I want an S2+ in every iteration imaginable!!!
I’m torn between singles and triples,but leaning heavily towards triples.Better efficiency,floody enough and with the right optic you can achieve anything you want!!The triple samsung is quite interesting too!
Do you have any recommendation on optics?