RED LEDs again

Having made up a T-13 with red LED, thanks to great information off this forum im wanting to do the same but with a T-20. I know its only 1 x 18650 battery but i only want 150 meters with the collimator head.

Why is the red led dimming when i do a straight swap or even put a different drive in. It starts nice and bright but after 2 seconds in dims a fair bit and then holds steady. not enough light then.

next question is i want a OSRAM - LRH9GP-HZKX-1-0-350-R33-Z - LED, OSLON BLACK, RED, 120 on a star. 17mm will do as i can make a washer for it to fit a 20mm hole.

Anyone have any idea where i can get a couple made up please. I can get the chip but cant find it on the star.

Any thoughts on a driver to fit this LED and T-20 torch please.

All the best


It is being over driven I believe. The VF of red is much to low.
I played with my a60 and a red xr and experienced the same. Here’s a thread discussing it.

As good as that thread is and as knowledgeable as those folks are one thing they failed to mention is when the amperage goes up so does the Vf. With improved thermal characteristics the increased amperage can be beneficial, of course to a point.

If you did a direct emitter swap in the t20 with original driver it is probably overdriven as mentioned above. Overdriven by a quite a bit creating excessive heat killing light output.

To fix the problem we would need more info. What method of star to pill attachment? What star Al or Cu? What emitter? What driver?what batteries?

I built a number of t20’s with red xpe’s on Al stars and fixed to pill with AA epoxy and driven at 1.4A with a 7135 driver. These versions did have good initial start up
Lux and about 10-15% drop after 5 min or so. The gains with 1.4 over say 1 A were worth it. I no longer attach stars to the t20 pill with AA. Cu stars soldered directly to the pill is the only way to go at this time.

I do have a few oslon ir LEDs on the way. They have the same footprint as the emitters linked above. Some have said they flow on to xpe stars. Looking at the data sheets I’m not so sure it’s possible. I’ll post as soon as I know. The osram red LEDs are spec’d to be able to take 2.5A surge. They may be more suited to overdriving than the Cree. Only one way to find out!

Thanks for the replys Gents,

Kevin, why do you make it so easy to read. haha! Normally i get baffled with some users wording, in fact i get baffled by my own at times.
Pleasure reading your posts. Thank you.

I have been told that that Osram Oslon Black red and be run the same as the Black IR. Just need to go and try understanding the specifications, im getting there and learning.

I might have to put an order in at Farnells as they have two drivers that i can use with a dimmer. only thing being is they do not do chips on stars so i will have to learn and buy whats needed to reflow on to the stars. But they do the oslan black red r33 and the CREE - XPERDO-L1-R250-00A01 - HIGH BRIGHTNESS SMD LED, RED ORANGE, 87.4LM Which im told are the same as being used in the nightmaster800, which we can not buy over here at a sensible price. Hence the reason i have been trying to make something similar.
Silly as it has cost me more so far.haha.

Just been looking around and i can not find any of the two on stars. looks like i have more to learn and by. Need a DMM first as the one i have on runs 10a.

I need to measure the driver for the T20 but of top of head i think its 17mm. the star size im not worried about as i can make up something for it to sit in.

waffling, lack or sleep. Im

All the best


Plenty of info on reflowing here on BLF. It is really quite easy.

The stars you can get either aluminum or copper for the xpe. Sinkpad does have Al stars for the oslon, however you would have to meet their minimum order dollar amount. The t20 takes 16 mm and with your centering ring idea will go together nice.

Get some parts and give it a go.

I had some, no A driver turn up today. i ordered 4 and got one.hehe. it was this one.
3.6V~16V 925mA Constant Current LED Driver Board for Cree and SSC LEDs (4-Pack)

and married it to this Red LED

OSRAM Oslon SSL 80 red on Star Oslon SSL 80 LRCP7P-JRJT (JS)—SSL/OSRAM-Oslon-SSL-80-red-on-Star-LT-1972_206_207.html

Its working ok, no drop in visual brightness, i have no lux meter.

im not sure on the trow of it yet so once dark i will go test. i have a felling i need a 50mm or even a 66mm lens. the Crelant head will not fit but i have just ordered a 59mm lens to fit the old T13 head. got to be woth a try.

as it is i dont like the size of the beam so i think i will shave the led lens down on another dark red led just to see if i can do it and if it tightns up the beam.

no idea when the ah is at the tail cap as i need a new DMM but i cant find one that with do the job, mine runs at 10A.