A solicitation for the design a pulse-detector which has to measure the precise duration of high intensity visible light flashes on the order of
10 nanoseconds, plus digitally record flash intensity during the pulse - "using Arduino." and constructible using only off-the-shelf components commonly available for purchase in Pakistan. Budget: $50
The detecting photodiode was what worried me, and Element 14/Newark
has the SFH2400-Z for $A2.07 one-off
It offers a 5nsec rise and fall time, which might be fast enough.
For pulse duration, you'd use it turn on a constant current into a capacitor, for the duration of the pulse and digitise the charge accumulated on the capacitor after the pulse had ended.
If the Arduino hasn't got a built-in A/D converter it would be easy enough to buy one and get the Arduino to read it's output.
For pulse intensity, you'd just put the photo-diode in series with the integrating capacitor, digitise the stored charged, and discharge the capaictor before the next pulse.
Not rocket science, but a couple of 5GHz wideband transistors might come in handy.
is PNP. There are lots of NPN parts around.
-- Bill Sloman, Sydney
The $50 budget is what you get paid for designing and constructing it, not the parts budget, btw. If you wanna collect please feel free...
Lol. He probably does. What was the parts budget, $3?
NT
NT doesn't have much grasp of reality.
An Arduino board cost of the order of $20.
I'm a bit more expensive. Thoughts about feasibility do come cheap, but they aren't worth much, even from the best of us.
-- Bill Sloman, Sydney
It's nice to start the day with a cup of strong Peets coffee and a good laugh.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
I could send the "client" the text of Bill's post for a fee of $50 and we'll split the profits a fair and square 50/50. Well it doesn't hurt to ask! 50 bucks is 50 bucks!
They say it's for a "stroboscope" mmhmm, I believe it, look pal if you want your nuclear bomb analyzer or whatever made right you can't cheap out!
Your task is simple. First you sign the NDA. Then you develop, design, construct, test, de-bug, market, and sell this widget I have an idea for. Then we split the profits 50/50. I'm really more of an "ideas" person, you see.
Keep in mind that in a world with ~8 billion people there probably actually is someone trying to outsoure the construction of a nuclear weapon via lowball offers for component-widgets they don't understand on freelance job sites. Scary.
Fortunately most "jobs" of this kind on freelance job sites are only solicitations to help design widgets which run off their own power output, y'know the usual. Just because they don't mention that this pulse counter has to run off its own power at the outset doesn't mean it won't be mentioned later...
Not all projects on sites of this type are silly. Many are. I've turned over some decent profit tho doing small jobs that were kinda-lowball bids but I have the gear and experience at this point to crank them out in a day or two, hey for say $500 or 1k why not cash is cash and I live a pretty modest lifestyle.
The more reality-based projects often originate in the US and they've subcontracted to some 2nd world country, and then the subcontractor is hoping to subcontracting some component nominally to a different 3rd world country...but I'm making America great again friends I'mma steal that job right back here! Hah!
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capacitor, for the duration of the pulse and digitise the charge accumulat ed on the capacitor after the pulse had ended.
enough to buy one and get the Arduino to read it's output.
the integrating capacitor, digitise the stored charged, and discharge the c apaictor before the next pulse.
come in handy.
,hey aren't worth much, even from the best of us.
An Arduino nano is around $2 (US) shipped from China. Assembled but DIY hea der soldering. That's an ATmega328, 16MHz resonator, chip CH340 serial-USB chip for programming and debugging, LDO-ish voltage regulator, USB socket a nd a couple LEDs on a board. They pre-program the bootloader so you can do everything over the USB with NO development hardware unless you find a way to erase the bootloader.
It's open source hardware so as cheap as can be. The programming environmen t is also free/open source.
If you just need a small quantity of small microcontrollers for test rigs o r little projects there's no need to go chip level at those prices, the nan o fits in about a DIP-40 footprint. There's a 32-bit version (STM32F103C8T6 ) and a Wifi version (the former based on an ARM and the latter on a Expres sif Systems (Shanghai) chipset).
Many chip makers are supplying Arduino libraries, which makes it a snap to get a chip up and running when you have to set up a zillion internal regist ers over SPI or I2C.
One may sneer at the hobby applications, but they have driven the quantitie s up and I think they're the cat's a**.
--sp
There was me thinking you were just the guy for that one :) They might need to get willing to add some zeroes though.
NT
10 nanosecond pulses would probably make it a low resolution (300cm) LIDAR detector, probably running at about 100KHz PRF. The problem is that it would only be able to detect pulses when the laser is aimed directly at the detector, or from a reflection which would ruin the intensity record. If the LIDAR is aimed in some other direction, the detector would have nothing to detect, so this isn't going to work. The best I could do is build some kind of omnidirectional photo detector, with a large capture area, and record a few pulses as the LIDAR scans across the capture area. Since the specs don't seem to care about the direction, spot size, and scan rate, a conical or hemispherical reflector pointed downward into a parabolic dish should work.
I suppose he wouldn't pay for telling him it won't work the way he expects.
"Introduction to LiDAR"
Drivel: I was thinking that there might be a market for a wearable personal LIDAR detector for pedestrians that would beep if it detected something resembling LIDAR pulses. That would warn the pedestrian that a driverless car or truck was approaching and to take the necessary precaution of running furiously to get out of its way.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Or activate some form of spoofing.
I wonder if our grandkids will have endless fun repeatedly starting to step in front of an oncoming vehicle to cause its "new obstacle must stop" neuron to fire.
If, of course, it has such a neuron... "If confirmed, it would be the third time a Tesla in autopilot has crashed into a stationary emergency vehicle this year"
yeah, but there's clones for $4
-- Notsodium is mined on the banks of denial.
Nowadays with library routines that make configuring ports, special function registers, etc. far easier than it was even 15 years ago I do most of my "embedded" development on the desktop, in C++, do the bulk of the writing and debugging there (using placeholder functions like sometimes just regular cout to represent IO calls on the actual hardware) and then "port" the code to the embedded AVR/ARM platform same as you would any other application ported to a new architecture.
Abstraction is great and reduces development time greatly, the overhead in is quite small with respect to larger binary size but IMO quite worth the price of admission for the time and frustration you save in the grunt-work stage.
IDE plug-ins like Compiler Explorer are great too, no reason in 2018 why code for small jobs shouldn't be compiled on the fly as you type, you can select multiple different platforms and view the assembler output in real time to sanity-check your work as you go
We started ordering Peets. Green Mountain has been cutting back on their decaf flavors so dumped their subscription service, after fifteen years. Peets is better than most but not as good as GMCR was, at one time. GMCR went downhill when they bought Keurig.
I haven't run into any stationary objects, but my Tesla has braked hard suddenly when driving under overpasses. It's only for a moment, but it gets your attention!
Rick C.
hard suddenly when driving under overpasses. It's only for a moment, but it gets your attention!
As does the ordinary response time driver behind running into the back of you?
Mike.
Plausible investigation plus conclusions, amusing photo:
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