Re: WTS: TWOH POP2 v2.31 Sammie or Jill Pill
@rikvee,
I don't have a lamda (I wish I have) where can I get one??
I think efficiency of the POP2 depends on the Vf of the luxeon being used. The lower the Vf the longer it runs and the brighter it is /ubbthreads/images/graemlins/grin.gif Provided an R123 or li-on is used.
If the Vf is H then the POP2 circuit will starts up 3volts. H my friend, is very efficient together with WO the color and tint would be very white indeed /ubbthreads/images/graemlins/grin.gifI I don't think you could find a better combo, an unobtanium UWOH would be brighter but does that bin exist? Hence the $25.00 price tag.
Here's a runtime chart DJPark did a while back with a POP2 and the TPS73201 LDO chip.
Mind you DJ used the TPS73201 LDO chip in this chart which tops of at 400-450mA, 99% of all the POP2 I made all use the TPS73601 this give a bit higher output current. Also I believe DJ's li-on battery has been charged and dis-charged numerous times and it's not up to par when he conducted the tests.
1) The RED is unmodded Q3 with R123 and BLUE is unmodded Q3 with CR123. In any combination of Luxeon bin with TPS73201(450mA) is brighter than Q3 + CR123 and also more consistent brightness.
2) CYAN lines are p-fet burst (=DD). On low Vf Luxeon with fresh charged R123, it is much brighter than LDO, but not long, less than a minute or so.
3) The jumping up of the brightness indicates the LDO going out of constant current regulation. From this point, it just give everything. the LDO has suppressed down the current by eating up the voltage while on regulation. If regulation goes off early, we get more light. That means we are actually wasting some potential light output by burning it as heat in LDO.
As you can see the TX1J (yellow) Ran for more than an hour. A TWOH lux has a lower Vf than a TX1J so it would run longer than a hour at the highest output.
To recap:
TWOH: tinit and color is very white, runs longer than J bin and at the same price $59.95 shipped and can be a POP2 V2.31 sammie or POP2 Jill Pill form factor.