33mm, 25A, 35V, adjustable LED driver - fits D-cell tubes! - thermally protected

[id30209]

Here's another idea for this beast. Unlike CBT-140 this LED requires a lot of voltage and a small amount of current plus it's more friendly to work with.
Huge heatsink is required anyway.

https://store.yujiintl.com/products/bc-series-high-cri-cob-led-bc160h-100w

Some specs:
Nominal Wattage: 100W
Rated current: 4000 mA
Forward Voltage: 23 - 27 V
Luminous Flux (3200K): approx. 5600 lm
Luminous Flux (5600K): approx. 6000 lm

 

[DIWdiver]

Yup, that's generally much easier to work with. But the emitter area is so large that you can't focus it into any kind of beam without an enormous reflector.

By the way, I just checked and your package is in customs at your country.

 

[id30209]

Thx DIW, i didn't even remember to ask )
Yeah, beside big hs big reflector is also required. But i belive that everybody has some giant head from previous projects

 

[Hoop]

It's about time to take apart the old SR-90 and put an SBT90.2 in it.

I'd like to buy one of your boards in 1s config, with 2.7v cutoff.

The plan is to use a double pole switch for on/off, and an external pot for dimming control. And a fet wired to the switch as well for aux power.

 

[DIWdiver]

Okay!

It's been some time since I thought about these boards, so it might take a week or so to build and test a board I can send you, but I can definitely do it. I'll start digging in the archives and getting out the test fixture.

 

[Hoop]

DIWdiver, your inbox is full.

 

[DIWdiver]

Not any more!

 

[Hoop]

Does this iteration of the driver feature a connection for an external temperature sensor?

"By connecting the H terminal to C, you get high, and by connecting L to C you get low. Disconnect both and you have OFF. The driver draws about 12 mA in off mode. This could be eliminated by using a double-pole switch."
It is not clear to me how the driver should be wired to eliminate the 12mA draw. Does this require a switch rated for the full amp load?

I would like to achieve all control via an external POT. Some POTs feature built in switches, either rotary style with the switch function at the beginning of the taper, or push button via pushing on the shaft. I am thinking that it this kind of pot can be set up to kill the 12mA draw so a toggle would not be necessary and all control can be done in a single POT. Examples of such pots: (50k log taper with rotary switch)(50k log taper with push button switch) Note that these examples are log taper, not linear.

Connecting the switch function of those pots to the gate of an external low resistance mosfet should do what I need which is eliminate the 12mA draw when OFF and control it all with a single knob.

 

[Hoop]

I see that you addressed the switch wiring in your other thread: https://www.candlepowerforums.com/v...inear-driver&p=4608551&viewfull=1#post4608551

Seems the switching pot will work without requiring an external mosfet to handle the current.

I am still trying to work out how to wire it though. The description is not clear to me. "Battery side of the switch?" I think you mean that battery positive needs to be wired directly to LED +?

 

[DIWdiver]

Built it six years ago, and I have to look it up to see what's going on!

Yes, it has connections for an external thermistor, the RT1 terminals.

Yes, it will draw some milliamps when on. If I said 12 mA back then, that's probably accurate. To wire the switch to kill that, it does not need to conduct the LED current, just the few mA of the driver. You just wire the LED directly to the battery+, and wire the B+ terminal of the driver through the switch to battery+. LED- goes to L- and B- goes to battery-. Open the switch, and the LED goes off, and the current drops to a few uA (leakage in the FET), regardless of what's going on with H, L, and C terminals.

You didn't say, I assume you are looking for the 25A version?

 

[Hoop]

I understand, thanks.

Yep, I am after the 25A version for the sr-90 mod. I also want to do a mag mod with one of these and that one should probably be 16.7A.

Why offer versions other than the 25A one if the current limit is adjustable? Is there a downside to the 25A such as higher dropout voltage? What parts change between the variants?

 

[DIWdiver]

Lower current versions have better sensitivity at low currents.

 

[Hoop]

What type and value of thermistor do you recommend?

 

[DIWdiver]

10K, NTC with B=3435 (or close). After that it's whatever you can get to make good thermal contact while being electrically isolated. The one I use on the board is Vishay NTCS0805E3103HLT.

A Vishay NTCALUG02A103FLA would be a good choice, and a little easier to work with.

 

[Hoop]

Does the driver feature reverse voltage protection?

 

[DIWdiver]

No, that was not included in the design.