I measured up to 70C in a somewhat enclosed space -- in thermal limit.
Out in the open, it does about 60C at 5W. The circuit will do 10W, but not
all cells will. :)
> Kewl. What voltages/current limits?
>
> Add a USB charging port and I'm in.
The cell is removable (or I guess you could shove some wires in and charge
it that way). Not that 18650 chargers are all that common.
Input voltage limit 3V (less and output current falls sharply), output
voltage limit 12V (just with a zener to the feedback node), output current
1A, input current, absolute maximum somewhere around 5A I think.
>
> Oh, uh, I should probably ask- what's the projected retail price point?
I have to look up how much they charge for kitting + fullfillment on this
sort of thing. It should be a nice kit for most learners, and with all the
control and sense signals accessible, it can be hacked into lots of things,
limited only by your imagination.
Tim
--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: https://www.seventransistorlabs.com/
Reply by nuny...@bid.nes●December 9, 20172017-12-09
On Tuesday, December 5, 2017 at 3:48:48 PM UTC-8, Tim Williams wrote:
Damn. Use enough heatsink there, Butch?
How warm do the LEDs get, anyway?
> Triple 'LVC buffer drives the power transistor at 5 or 6 nanoseconds
> risetime, not bad at all.
>
> Design is very hackable; by changing around a couple of resistors, it makes
> a portable bench supply!
Kewl. What voltages/current limits?
Add a USB charging port and I'm in.
Oh, uh, I should probably ask- what's the projected retail price point?
Mark L. Fergerson
Reply by John Larkin●December 6, 20172017-12-06
On 6 Dec 2017 10:46:27 -0800, Winfield Hill <hill@rowland.harvard.edu>
wrote:
>John Larkin wrote...
>>
>>>> NL37WZ16US, all three sections in parallel:
>>>> https://www.dropbox.com/s/v3b284refb3hmx9/NL37WZ16_Rise.jpg?raw=1
>>>> and I've seen much faster.
>>
>> Those tiny buffers are so cheap that you can put two or
>> three in parallel, at three gates per chip. More drive,
>> less wirebond inductance. Run them at abs max Vcc, of course.
>
> Even three in parallel, Rds about 5 ohms, right?
Sounds about right.
> It'd be nice to be 10 to 20x lower.
Sure, but that gets more complicated. And expensive. Inductance gets
to be an issue out there.
An alternative is to use multiple smaller fets in parallel, each with
a couple of private tiny-logic gate drivers.
That spreads out the L di/dt's and the thermals.
--
John Larkin Highland Technology, Inc
picosecond timing precision measurement
jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
Reply by Winfield Hill●December 6, 20172017-12-06
John Larkin wrote...
>
>>> NL37WZ16US, all three sections in parallel:
>>> https://www.dropbox.com/s/v3b284refb3hmx9/NL37WZ16_Rise.jpg?raw=1
>>> and I've seen much faster.
>
> Those tiny buffers are so cheap that you can put two or
> three in parallel, at three gates per chip. More drive,
> less wirebond inductance. Run them at abs max Vcc, of course.
Even three in parallel, Rds about 5 ohms, right?
It'd be nice to be 10 to 20x lower.
--
Thanks,
- Win
Reply by John Larkin●December 6, 20172017-12-06
On Tue, 5 Dec 2017 19:18:19 -0600, "Tim Williams"
<tmoranwms@gmail.com> wrote:
>"John Larkin" <jjlarkin@highland_snip_technology.com> wrote in message
>news:7bde2dhe2t4mdfqms33barde32uv5fh78h@4ax.com...
>>>https://www.seventransistorlabs.com/Images/FlashlightTrio.jpg
>>>
>>
>> Looks bright.
>
>That's the lowest setting. :^)
>
>They're capable of 10W, though the 18650 cells I have aren't capable of that
>much, they start to brown out (the circuit has an undervoltage limit so it
>doesn't collapse).
>
>Needless to say, full brightness does not photograph very well...
>
>> Some of those tiny CMOS parts are insane.
>>
>> NL37WZ16US, all three sections in parallel:
>>
>> https://www.dropbox.com/s/v3b284refb3hmx9/NL37WZ16_Rise.jpg?raw=1
>>
>> and I've seen much faster.
>
>Yup. These gates have a pretty good load on them, actually: the Vgs
>waveform is about 20ns. And the power transistor is sharpening up the rest.
>
>Tim
Those tiny buffers are so cheap that you can put two or three in
parallel, at three gates per chip. More drive, less wirebond
inductance. Run them at abs max Vcc, of course.
--
John Larkin Highland Technology, Inc
lunatic fringe electronics
Reply by ●December 6, 20172017-12-06
On Wednesday, 6 December 2017 01:24:56 UTC, Tim Williams wrote:
> <tabbypurr> wrote in message
> news:57f83509-9e2f-44ac-8f40-ad02387151ec@googlegroups.com...
> > On Tuesday, 5 December 2017 23:48:48 UTC, Tim Williams wrote:
> >> These are fun!
> >> https://www.seventransistorlabs.com/Images/FlashlightTrio.jpg
> >
> > so it's promotional
>
> Buy now and get 5% off! :-P
>
> >
> > why so much electronics in a flashlight?
>
> It's a demonstration -- discrete (transistors, comparators, op-amps and a
> gate driver) yet full featured. Boost converter, average current mode
> control, 2% regulated output voltage/current, adjustable, overvoltage
> (output) limit, undervoltage (input) limit, overtemp limit.
>
> You know, everything you get inside a teeny $1 IC, for the price of $20 in
> parts and a whole PCB. :-)
>
> Tim
I'm not seeing the point of it.
NT
Reply by Tim Williams●December 6, 20172017-12-06
> Is that the LED current rise time or the rise time of the photo current?
> (a modulation input somewhere?)
Boost converter, filtered output. Risetime is of the converter switching.
Modulation isn't very fast, on account of the converter + controller being a
big filter, ~kHz BW.
It would be less efficient (and much more EMIey :) ) if the LEDs were right
across the boost inductor (and also slightly harder to regulate current),
due to the RMS AC current in the LEDs' ESR. The blue spectrum would have
about that rise time then, though.
But you could also assemble the design that way, if you so desired.
Tim
--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: https://www.seventransistorlabs.com/
Reply by George Herold●December 5, 20172017-12-05
On Tuesday, December 5, 2017 at 6:48:48 PM UTC-5, Tim Williams wrote:
Is that the LED current rise time or the rise time of the photo current?
(a modulation input somewhere?)
George H.
>
> Design is very hackable; by changing around a couple of resistors, it makes
> a portable bench supply!
>
> Tim
>
> --
> Seven Transistor Labs, LLC
> Electrical Engineering Consultation and Contract Design
> Website: https://www.seventransistorlabs.com/
Reply by Tim Williams●December 5, 20172017-12-05
"Clifford Heath" <no.spam@please.net> wrote in message
news:9sGVB.9922$HA4.8538@fx35.iad...
> Your design Tim? Otherwise where are they available?
>
Yes. Nowhere yet, haven't decided if I'll just do it on a one-off basis, or
make a kit of it. I should see what Tindie is like for these sorts of
things...
In any case, do send me an e-mail if you're interested. :)
Tim
--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: https://www.seventransistorlabs.com/
Reply by Tim Williams●December 5, 20172017-12-05
<tabbypurr@gmail.com> wrote in message
news:57f83509-9e2f-44ac-8f40-ad02387151ec@googlegroups.com...
It's a demonstration -- discrete (transistors, comparators, op-amps and a
gate driver) yet full featured. Boost converter, average current mode
control, 2% regulated output voltage/current, adjustable, overvoltage
(output) limit, undervoltage (input) limit, overtemp limit.
You know, everything you get inside a teeny $1 IC, for the price of $20 in
parts and a whole PCB. :-)
Tim
--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: https://www.seventransistorlabs.com/