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. > >TimThose 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
Flashlights
Started by ●December 5, 2017
Reply by ●December 6, 20172017-12-06
Reply by ●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 ●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 ●December 9, 20172017-12-09
On Tuesday, December 5, 2017 at 3:48:48 PM UTC-8, Tim Williams wrote:> These are fun! > https://www.seventransistorlabs.com/Images/FlashlightTrio.jpgDamn. 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 ●December 9, 20172017-12-09
"nuny@bid.nes" <alien8752@gmail.com> wrote in message news:29c2a8cb-24ec-41a0-b8a7-4d4c079ccd59@googlegroups.com...> On Tuesday, December 5, 2017 at 3:48:48 PM UTC-8, Tim Williams wrote: >> These are fun! >> https://www.seventransistorlabs.com/Images/FlashlightTrio.jpg > > Damn. Use enough heatsink there, Butch? > > How warm do the LEDs get, anyway?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/
