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Jeremie Francois
Works at TecRD
Attended UTC, France
Lives in Montpellier
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Jeremie Francois

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I am getting better each time at isolation milling with manually pre-broken V-cutters. The solid pour on the first image around the trace for the antenna shows how large is a single pass. Check also the SMT pads that shows the radius on the V-cutter. I think I will settle on two everywhere for my next jobs, as it is already significantly faster for 4 to 3...

Still, manually changing the drill bits is a real pain... and it is prone to error: 1) I broken one after forgetting to clamp the Z probe, and 2) I mismatched and chose a 1.2 mm bit in place of the 1.0, which almost ruined the pads (I consider myself lucky).

Anyhow, this was done out of an atrociously cheap single side 70x50 mm PCB, which I bought on ebay (really: I got 50 of them for about $15!). The copper layer is so-so and tears easily. It is certainly not FR4 (glass-epoxy) as advertised. It looks like old-school bakelite instead... but it still works fine enough for the price.

Nb1: software = Eagle(not for long now?) + pcbgcode.ulp + LinuxCNC + AutoLeveler

Nb2: about willingly pre-breaking tips, I wrote why here This time I achieved a two-break, slightly pointy, and slightly off-center tip, with a very good attack edge. And it worked pretty well to my standard, even though there are a few ragged edges left at some place on the PCB. I will try the "prefer climb" option of pcb-gcode next time, as I suspect it is the main culprit.
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Wow some eventually did it :)
The slicer must be tricky though, but it really should help in many cases. It reminds me of one of my oldest posts: ... made real :)
[Oliver Tolar] and [Denis Herrmann], two students from the Zurich University of Applied Sciences (ZHAW), designed and produced a 3D printer prototype that has a movable printing bed that can tilt. By tilting, objects with critical overhangs can be printed…
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The TV crews had globally nothing to tell, showing again and again the very few images they had like in a bad sensational show. I wished they talked about this one just a little bit :/ The deal was hard but they eventually made it this time, kudos!
This electric car is the first zero-emissions vehicle to finish the Dakar Rally

The Acciona 100% EcoPowered rally car powered its way to the finish of the world's toughest motor event without burning a drop of fuel and with no tailpipe emissions.

Built entirely in Spain, the home of Acciona (which is a leading Spanish renewable energy and infrastructure firm), the EcoPowered rally car is said to be "the most powerful electric car in the world" thanks to a 250 kW electric motor capable of producing 340 horsepower, coupled with six "ultra-fast charging" lithium battery packs with a 150 kWh capacity, and an onboard 100 W solar panel. With that battery and motor combo, the vehicle can run for about 200 kilometers "in race conditions," with a 60 minute charge time to 'refuel' the batteries.

The Acciona 100% EcoPowered rally car powered its way to the finish of the world's toughest motor event without burning a drop of fuel and with no tailpipe emissions.
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April fool before the day? YES, after 6+ years of jail (only because s/he revealed some serious abuses by the state), he should be released free! :) This is ridiculous nonetheless, that presidents may have opportunities and free hands to do this, and that they do it only on their last days. What kind of justice is this when whistle-blowers get jails without a proper (public/regular/non-militray) trial, a proper sentence (no parole), and being able to get freed by one person afterwards ... three decades early?!!
I wish Snowden is next, even though but he might want to wait a bit before returning to the USA anyway... At least he could stop risking being extradited by allies and start having a life again (
Oh and there is Assange btw.
And there are a few prisons to close (as expected, eh?), namely those that were settled outside of the public territory (how?! I ever wished I knew the kind of super-ugly deal there are with the hosting countries... They ought to be illegal by the most basic international human right standards).
Free but limited time to clean some year-long mess? Amazing country :(

David Clunie's profile photoJeremie Francois's profile photo
+David Clunie I agree with you. The 3 of them (Manning, Snowden, Assange) are all 3 different cases, but they all could be pardoned. Still, the fact that one of them spent years in jail and not the others is irrelevant of the very "reasons" they all got in trouble: letting people know about dubious or plain illegal/nasty acts of our own governments and secret services that they are uneasy to let us know about (to say the least...).

The contrast is very visible in the USA-as-a-leader-of-the-free-world, but it really happens everywhere around the world, be it "free" or "not". This is no rant against the USA, by no means, except that it exacerbates the problem. As I always say, the biggest critics of the USA also come from the USA (e.g. M. Moore).

Rich or wellknow people get special treatments.

E.g. approximately at the same time that a guy was sent to 5 months of jail for stealing rice and pasta in a shop (!), high profile people like the IMF head Lagarde git cleared for "negligence" for (almost) giving out 400M€ of public money to a French tycoon. She even got judged by "special" biaised jurisdiction, i.e.. mostly political ppl judging political people.

Everyone pays for whet she called "negligence that everyone does".

The powerful woman keeps her power, the rich guy gets richer, and the hungry man gets free lunch in a jail.

Oh, and the torturers are not judged at all, as a few scapegoats hide them all.
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Incredible & condensed stuff to know for solar + batteries setups (below, not my own stuff here!!).
Ours is differing mostly because we have no batteries... yet. I.E., we are still attached to the grid. When deep-cycle batteries become cheap enough, we will probably jump, and add another set of panels.

For now we have 12x 260 watts solar panels, equipped with individual enphase microinverters (this is more expensive than one big and hardly extensible inverted, but it gives better results (b/c/ they optimize each panel individually), and/so we can spread the arrays and flatten the production through the day (~16+kWh). Check my previous post on the matter:

Then, a raspberry remote-controls the heaters thanks to a few sonoff wifi switches (see The active heater combination are chosen to make the best of the actual production, which I read directly on the (crappy) tiny page that the enphase "central" broadcasts on the local network. As the latter updates the production only every 5 minutes, I plan to bypass it completely by reading the current closer to the solar panels (with some Arduino and a RF link, contrary to the existing powerline networking). Right now, the enphase "envoy" gives useless values for sunny days with scattered clouds.

For now I only can switch between 4 levels because of our various heaters. So I am considering using PWM on one heater at least so as to optimize the production. I also have to redo the water heater (e.g. for this role): for now it runs on a standalone bluetooth controller (!), which behaves better and cheaper than the former "industrial" day/nigh 80+€ controllers that kept on dying every two years!

All this stuff is incredibly cool to control :)
Well, I mean, warm.
Lessons and Tips I have Learnt on my Solar Installation

Some lessons I have learnt over the last year after having to replace one or two components are:

1. Save now, and you will replace later. Also you need to decide if you want a full system to power everything, or just want something to power the lights and some essential equipment.

2. Try go for 24V as it is more efficient, and cheaper cabling too. So buy batteries in pairs so that you can create a 24V system.

3. If you want remote management, make sure what system each device can report to. It won’t help buying one Victron inverter but using an Ellies solar charge controller as you will have to go to two or three places to look at what is happening.

4. The heart is the batteries:
a. You only get to use 50% of the stated capacity as you cannot run the batteries down to below 50% - so a 300Ah battery capacity is going to give you 150Ah of real use.
b. Work out what you want to power – the max load (peak) at any time, will determine what size inverter you need. The total amount of power used during the night for everything with some spare left, will determine what capacity of batteries you need.
c. Lead acid is fine for backup or UPS functionality, but if you intend to cycle the batteries down to 50% daily, you will need better batteries. It will be deep discharge batteries needed.
d. You can wire batteries in serial and parallel to get your 24V and enough capacity – but total capacity is is determined by the total number of batteries you buy.
e. You are not supposed to mix different capacities, brands, and old/new batteries, otherwise you stand to kill your newer batteries. So try buy the right number to start with.
f. Don’t connect the inverter and solar charge controller all to a single battery's terminals. Connect their negative to one battery, and connect their positive to a battery on the other end of a parallel setup – this spreads the load more evenly across a parallel setup.

5. Solar panels can also be wired in parallel to get more current, and with a 24V system you can even put them in serial to get 24V. You need to buy enough so that it can run your daytime usage (normal current used for a sunshine day, plus to charge your batteries. So four 120W panels are charging my 300Ah batteries and running other stuff in the day. But 600Ah batteries will likely require 8 panels. Obviously and extra panel or two is going to help for overcast days.

6. On the solar charge controller (this regulates the power from the solar panels to be safe for the system and the batteries):
a. Luckily they often are dual 12/24V output so you only have to consider their maximum Amps and Volts they will handle, and the type of controller.
b. Maximum Amps will determine how many solar panels you can add to it (look at maximum output of the panels eg. mine are about 6Amps per panel.
c. Maximum Voltage input is important because it also determines how many panels you can connect in serial (as the Voltage is higher, which is more efficient and cheaper cabling again).
d. The PWM controllers are cheaper, but are also slower to respond to partly cloudy weather so you lose efficiency. The MPPT controllers cost more but are much faster and more efficient (and recommended that you wire the panels in a 24V configuration for MPPT controllers, as they will start charging quicker in the mornings).

7. On the inverter (converts your battery voltage to 220V) they are often a set input voltage (12V or 24V) so your battery setup helps determine this choice and then you stick with it unless you want to replace the inverter later on. But consider also:
a. Continuous power rating (in Watts) – this is the constant load it will support. In my house the LED lighting, a pond pump, lounge TV, a computer, and the Internet modem and router all draw about 300 Watts at 220V. But kettles, geysers, etc are going to be at least 2kW each and remember they can run together. Someone did say that electricity is not the best way to cook and heat – and gas may actually be better for them, which lowers the cost of your solar system.
b. Their peak power rating (this handles short spikes like for a fridge motor switching on – if not high enough, a fridge will trip your system). So often you will see 600/1200 as a spec which implies 600Watts continuous power and short peaks of 1200 Watts can be handled.
c. You get standard inverters (just invert the power to 220V) and you get inverter/chargers (where the latter will also supply 220V to charge the batteries on say cloudy days, and they will often also act as automatic UPSs where they will switch to batteries if the grid power is off, or vice versa. It all depends on the battery type and how the inverter/charger can be setup and programmed so it is worth discussing these expectations to be sure of what is possible.

8. Wiring:
a. You do need a registered electrician for any 220V that connects to the house. And get an electrician who has experience with solar as from the above, you will appreciate their are nuances over and above what an electrician knows about 110/220V systems.
b. You do want a separate distribution board installed so that any circuits running from the inverter, are separate from any direct Eskom fed 200V circuits.
c. If you are mixing grid and Inverter power, you may find that some of your plugs and lights share common negative, and these will need to be separated by the electrician.
d. You do need to have fuse/isolator switches fitted to isolate power from the solar panels, from batteries, from inverter, and also for any power going into the sub-DB.
e. There is also usually a switch fitted to select between inverter and grid power supplying the new sub-DB so that if there is any fault on your solar setup, you can switch to just using normal grid power to those circuits.

9. Management: With systems like the Victron you also need something like a Color Control GX (CCGX), which is essentially small Linux computer with a status display – it pulls the data together and transmits the data to Victron’s cloud (where you can monitor it remotely or have alarms sent to you). Some of the individual devices will connect via Bluetooth devices but a single central monitor is better.

I hope these tips will help newbies before they start out, to ask the correct questions when planning a system. If anyone else has additional tips, or corrections, please add them in the comments.

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Michael Gebetsroither's profile photoJeremie Francois's profile photo
+Michael Gebetsroither wow I will have to re-read the figures... The switch may come earlier than I thought :)
For some time I somehow eyed second-hand EV batteries, but they are hard to find. I have space in my attic for less-than stellar batteries. Destroying lead-acid batteries because I discharge them too much is probably impossible with a proper controller anyway, but I do want a long life indeed ;)
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Heh learning everyday: what are these ubiquitous, funny-looking, round windows on ships? Spoiler: some are rotating as fast as 1500 rpm (!).
This is one of the (few) interesting things I knew existed but that I never asked about myself enough [the order of the words is important here: there are certainly (exceedingly many) interesting things I am not aware of at all]. May be I could start a specific "random knowledge" collection :)
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For those who were telling me it was not a good thing that Autodesk bought Eagle CAD some time ago: you were quite right. This software is extremely popular to design printed circuit boards cheaply. It was used for ages by hobbyists, but the new policy will probably push a lot of people towards KiCad (which is a very good thing for this opensource program!).

Actually, the worst is to come
for those who did pay a license to unlock the extended size or number of layers. Because they will have to pay more than once just to reopen their old designs even if they stop using eagle. :/

And for others like me, we should make sure to keep a backup of the existing installers for the "free" versions, as I suspect it may not be wise to trust Autocad further.

All in all, many hobbyists like me will feel the need to switch to the opensource KiCad EDA: no greedy company will kill it any time. There are also a few serious companies like +OLIMEX​​​ which do real and complex designs with it (and which promote it), so it is probably mature enough. Oh andit is really and forever free, this one.

EAGLE user? We hope you like subscription fees. Autodesk has announced that EAGLE is now only available for purchase as a subscription. Previous, users purchased EAGLE once, and used (often for years) before deciding to move to a new version with another…
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Peter van der Walt's profile photoErnie Peters's profile photoMidnightVisions's profile photoJeremie Francois's profile photo
+MidnightVisions exactly, I also want to own what I paid for!
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OK, well, Farnel did send the diodes I ordered. But I probably overlooked the package. I wanted smaller ones than what I had in SMT. But what on earth will I do with these now? :D
Stephen Baird's profile photoJeremie Francois's profile photoChristoph Pech's profile photoGiligain I.'s profile photo
What package? Still in transit and maybe lost...need money back. 
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A very interesting SAMD21 (32bit, 48MHz) super minimalist board for 25€ shipped worldwide, by +Albert van Dalen. I shall get a few of them for both pro & hobby uses, as they are probably one of the finest options out there!
(via +Jean-Luc Aufranc)
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Actually I find it pretty hard to find palettes anymore because the good ones are all re-used or recycled. It used to be a good source for building furniture imho also. And well, it was super heavily treated against the elements, as most of the wooden electric poles and public fences are: chrome + copper + arsenic afaik. This became illegal years ago for obvious reasons and they now no more last as much outdoors :/
Peter van der Walt's profile photoJeremie Francois's profile photo
The support structures are 12 year old, and they start to crumble only now (too bad, I liked the benches a lot). Only the table itself was made out of pine, and I had to replace it twice (we have nasty cycles of freezing/heating in winter).
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Variations of particles in a vector field. The (now) usual idea is to illustrate winds dynamically, according to actual weather data and better than with ugly arrows. Pretty easy to make (I am an old demomaker so it is just awesome to be paid for this kind of work!). It is barely slightly harder to optimize and make it pretty. The movement of the second picture is extremely soothing, while the first one draws an interesting map of the Earth. this is due to the fact that low altitude winds are significantly slower on earth than on oceans, hence the shorelines often show up. The background colors shades are the wind speeds.
I cannot wait to see this being used on my client's own maps (which is the most satisfying part of the work to me!).
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Jeremie's Collections
An open-minded technophilic iconoclast driven by curiosity.
If you know me and you cannot tell exactly what my real job is, then you probably found the right Jeremie. Check for some pointers.

I am self-employed and I help start-ups, research centers, small companies with their needs related to computers, sensors, data processing and mechatronics. If you have a project and know what "R&D" is, then you already sparked my interest ;)
Bragging rights
Coded an award-winning pinball game on palm. Published R&D papers in IEEE. Drove my motorbike deep into Sahara sands and in freezing Iceland. Wrote a popular blog by chance (featured in wired and hackaday!). Swam in a warm volcano lake. Kept all my friends so far.
  • UTC, France
    computer science, 2000
    PhD + engineering degree
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Whatever I can that I did not try yet!
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