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March 28, 2015
News - Colorado Doesn’t Need t…
about 3 weeks ago
Do not disagree with the young Mr. Seidle’s comments. But methinks that both himself and the Wired writer have missed some important ‘features’.
SF actually makes stuff. SF adds to our GDP by selling physical goods that have real value. Conversely, much of the SV hoopla is based on services - JS/PHP, and other such nonsense that, while can have some value as IP, remain abstractions with no tangible, measurable, immutable value.
And the other big difference and point (not the one on my head). The article’s protagonists is yet another unethical, non-engineer, big-payout wannabe. Our local hero (Seidle) has grown in a controlled and disciplined manner without depending on the Big Exit. Common examples external to SF (that would be familiar to this group) of disciplined, ethical business models are PJRC and Adafruit; so it is done outside of SV - if not just trying to hatch another get-rich-quick scheme/scam.
about 2 months ago
You EU peoples had best be circumspect with any monitoring done with this stuff. A relative in the old country hacked some Nikon coolpix cameras to make a generic monitoring system with tracking smarts, then promptly caught some local brats doing bad stuff to her property, then became the subject of an investigation by local LE when the visual evidence was presented.
On this side of the cod pond, you will need to read your state’s code. Most states do not care if you call it a security system, but some states and locales have regulations for monitoring people and collecting and/or storing data on privates.
As for most image processing, desktop Python is my preference. C or Python may not be the issue - as embedded systems simply do not have the resources that a desktop Linux box or OSX box would provide. And windoze will only provide headaches and anger.
Geez, been tons of code for this stuff for years. You people ever try that fancy-pants search engine by them google folks? Your inner Big Brother awaits the wakening.
Look at openalpr and opencv. But you will not like doing this with micropy.
about 2 months ago
Do not understand this as a “new” product because distributors no longer carry BMP180 and indicate it is obsolete.
about 4 months ago
Not necessarily a problem - use the relays on the board to control a power relay.
To control DC current, use at least two relays in series. Paralleling relays is not good.
Background. At the 2016 IEEE Product Safety Engineering Society symposium, the use of ‘hobby’ (arduino) processor boards, and related power-control related modules that have found their way from the home shop to the industrial/commercial setting was discussed. Should be noted that the director of OSHA’s NRTL program was present at some of these discussions, so the feds are now aware. An informal poll among a group of compliance engineers indicated some have direct experience with “more than one” incident related to use of non-compliant arduinio stuff.
Your efforts to design a conforming product are commendable and very much appreciated. Compliance requirements are a morass and lie at the unholy intersection of law and physics. Few designers have successfully navigated a formal product submittal for stuff intended to be connected AC mains; most have to seek a member of the Dark Side of engineering (that would be me) to avoid being seduced by the power of hate and anger.
Am not at work, so clause number and wording from standards are based on my diminishing ability to remember the multitude of garbage in the hundreds of standards and directives that taught me to embrace my anger and hate and serve well to crush my being on a daily basis.
creepage requirements for 60950-1 are similar, as both are based on IEC60664-1. The seminal reference for the physics of electrical spacings is K. Stimper, ”The physical fundamentals of low-voltage insulation coordination”, VDE-Schriftenreihe, Vol. 57, Berlin, Offenbach vde-verlag
. Per 60950-1, a minimum clearance (spacing through air)is 1.0mm for 120V, but this number has no margin and is intended for a widget that is enclosed in a box. Spacings for safety are based on the mains transient voltage for the intended OV category. So the absolute minimum transient rating for 120V mains would be 800V, which is used to determine the increased spacing for ‘Basic Insulation’ and to ensure that the equipment can pass the di-electric withstand test (‘hi-pot’). A more realistic transient voltage would be 1500V, which is the typical test level for Class I equipment per 60950-1.
Many are in denial on the impending cruel death of national standards based on IEC60950-1, so will ignore UL62368-1 and only reference product conformity per CSA/UL60950-1.
Would typically not recommend seeking a component recognition from UL, as there are other competent NRTLs that have more reasonable scheduling and rates.
Subclause 1.5 and annex P1 - ratings for PCB material per UL796.
subclause 3.2 and annex P1 - ratings for connectors per UL498.
subclause 3.3 and annex P1 - ratings for field-wiring connectors per UL486.
May the Light Side of The Force guide your future design efforts. And we all know that “once you start down the dark path, forever will it dominate your destiny”. So there is no hope for me…
Nothing written is intended as professional design advise for the purpose of compliance with various national safety regulations, standards, or directives.
IEC/UL/EN60950-1 is obsolete, and should not be used for assessments of new products.
Does not meet construction and/or performance requirements per CSA/UL/EN62368-1 and/or 60950-1.
Could meet UL/EN61010-1 requirements where used per specific conditions of acceptability. But probably non sequitur, as the scope of this equipment is not intended for use in professional test and measurement equipment.
Not recommended for switching motor power where nameplate rating for FLA or FLC exceeds 50% of relay contact rating. Not recommended for DC current interrupt.
Creepage (spacing across a surface) requirements in mm, per IEC62368-1:
120V Basic = 2.4, 240V Basic = 4.0
120V Reinforced = 4.8, 240V reinforced = 8.0
[these requirements for material group III, pollution degree 3]
News - Friday Product Post: A Ch…
about 4 months ago
The Si7012 spec sheet has this information. Anyone using these polymeric capacitive sensors should be aware of lifetime for a 95% confidence reading. My experience has been typically 6 to 22 months until replacement required, regardless of the mfr or model.
Best long term stability is the wet/dry ‘bulb’ using thermocouples or RTDs. But these are mechanically complex and require a way to control the flow of distilled water. Have made several in previous 20 years, and all remain operable and accurate while installed in very harsh environs.
about 9 months ago
for both 2811 and 2812:
Should work with all T 3.x stuff.
about 10 months ago
Bought book for niece off of Amazon, as she uses this silly program. Book is a bit dated and not complete.
Do not understand why the FOSS community pushing this closed and marginal program. Should be supporting stuff like KiCad (and there are many other decent OS systems for EDA). Last year, the PCB designers at my employers reviewed several low-end and FOSS systems, because Mentor Graphics and Cadence/Allegro licenses are getting too expensive. The only low-end package they considered usable and reliable was KiCad - which is my preference for both home and work. Their analysis became important when we layed off the drafting dept, and the engineers and techs had to do our own stuff. Am most happy we did not get stuck using Eagle. FWIW, we bought Eagle’s hi-end commercial package for our evaluation, so the Mentor/Allegro comparison is valid.
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