Forums

Flashlights

Started by Tim Williams December 5, 2017
These are fun!
https://www.seventransistorlabs.com/Images/FlashlightTrio.jpg

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!

Tim

-- 
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: https://www.seventransistorlabs.com/ 

On 06/12/17 10:48, Tim Williams wrote:
> These are fun! > https://www.seventransistorlabs.com/Images/FlashlightTrio.jpg > > 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!
Your design Tim? Otherwise where are they available? Clifford Heath.
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
> 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! > > Tim
why so much electronics in a flashlight?
On Tue, 5 Dec 2017 17:48:23 -0600, "Tim Williams"
<tmoranwms@gmail.com> wrote:

>These are fun! >https://www.seventransistorlabs.com/Images/FlashlightTrio.jpg >
Looks bright.
>Triple 'LVC buffer drives the power transistor at 5 or 6 nanoseconds >risetime, not bad at all.
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. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
"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 -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: https://www.seventransistorlabs.com/
<tabbypurr@gmail.com> 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 $20 in parts and a whole PCB. :-) Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: https://www.seventransistorlabs.com/
"Clifford Heath" <no.spam@please.net> wrote in message 
news:9sGVB.9922$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/
On Tuesday, December 5, 2017 at 6:48:48 PM UTC-5, Tim Williams wrote:
> These are fun! > https://www.seventransistorlabs.com/Images/FlashlightTrio.jpg > > Triple 'LVC buffer drives the power transistor at 5 or 6 nanoseconds > risetime, not bad at all.
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/
> 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/
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